Copyright © 2015 American Scientific Publishers All rights reserved Printed in the United States of America Journal of Low Power Electronics Vol 11, 349–358, 2015 A 65 nm CMOS Ultra-Low-Power Impulse Radio-Ultra-Wideband Emitter for Short-Range Indoor Localization Mohamad Al Kadi Jazairli∗ and Denis Flandre ICTEAM Institute, Université Catholique de Louvain, Louvain-la-Neuve, 1348, Belgium (Received: 14 April 2015; Accepted: 15 July 2015) This paper presents an ultra-low-power IR-UWB pulse generator based on a dedicated design of a chain comprising of a voltage controlled ring oscillator, a buffer and a pulse shaping filter A control voltage can be used to set the pulse repetition frequency The design was made using 65 nm CMOS technology The design was optimized in order to meet target specifications (pulse width, repetition frequency, PSD, etc.) that are suitable for short-range indoor localization The generator produces a pulse having 0.5 ns width and 930 mV peak-to-peak amplitude prior to the antenna The −10 dB bandwidth is from to GHz with an amplitude less than −40 dBm/MHz which makes it compliant with the FCC spectral mask The energy consumption is 1.5 pJ per pulse while the energy driven to the antenna is 60 to 65% of the total energy consumed by the circuit per pulse According to the state-of-the-art, this is the minimum consumption that we were able to achieve Delivered Ingenta unknownTransmitter, Copyright:UWB Keywords: Impulse Radio, Low by Power, Pulseto: Generator, American Scientific Publishers INTRODUCTION Ultra-Wideband (UWB) technology appears very promising for radio communication and localization UWB signals have a very wide bandwidth with allocated frequency spectrum from 3.1 GHz to 10.6 GHz and with a maximum emitted power being restricted to −41 dBm/MHz in compliance with the Federal Communications Commission (FCC).1 Energy can be spread over a very wide bandwidth to very low levels allowing UWB radios and narrowband broadcasters to share the spectrum without causing undesirable interference; this in turn generates numerous interesting and novel application opportunities These characteristics of UWB implementations are of utmost interests for low-cost, short-range sensors and smart devices with ultra low power consumption Another advantage of the low power transmitter is the size reduction of the transmitted antenna which allows a single die transmitter to be implemented in an area of mm2 In this work, one of our objectives is to design an extremely low power CMOS-integrated pulse generator for short-range indoor localization In order to achieve this, we considered the common form of UWB that is ∗ Author to whom correspondence should be addressed Email: mohamad.alkadi@uclouvain.be J Low Power Electron 2015, Vol 11, No called IR (Impulse Radio) which employs sub-nanosecond pulses without a carrier signal The transmitter can be used in both pulse-amplitude modulation (PAM) and pulseposition modulation (PPM) Several IR-UWB circuits have been proposed in the literature To produce the UWB output pulse, some papers used the LC topology3–5 while others used the ring oscillator topology.6 Those who used the LC topology managed to produce a sub-nanosecond pulse (∼0.5 ns) but in expense of high consumption of energy per pulse (> pJ/pulse) While those who used the ring oscillator topology managed to consume less energy per pulse (< pJ/pulse) but failed to produce a sub-nanosecond pulse Here our target was to reach sub-nanosecond pulse with an energy consumption of less than pJ/pulse Other implementations details will be compared in a later sections We have expanded the Voltage Control Ring Oscillator (VCRO) circuit architecture presented in Ref [8] In Ref [8], 0.5 m SOS technology was used to produce a single pulse with 800 ps width but without taking into consideration the exact UWB requirements on the pulse shape Here by porting this VCRO to 65 nm CMOS and introducing a proper design of buffer and pulse shaper, along with the right element sizes and filter shaping circuit, we can generate a pulse shape with a Power Spectral 1546-1998/2015/11/349/010 doi:10.1166/jolpe.2015.1393 349 A 65 nm CMOS Ultra-Low-Power IR-UWB Emitter for Short-Range Indoor Localization VCCB VCCA P2 C1 P3 M0 Ca 1 n1 n2 Normalized FCC mask Cb RL RL L n3 V control VCRO Pulse Shaping Filter Buffer Antenna S21 (dB) P1 Jazairli and Flandre Pulse Shaping Filter –20 Normalized transfer response of the pulse shaping filter Antenna –40 Fig Proposed UWB pulse generator 10 Frequency (GHz) Fig Implementation and frequency response of the pulse shaping 1.2 V1(V) Output voltage (V) Density (PSD) which complies with the FCC mask One of filter the most important issues addressed in the design has been achieving ultra low power consumption while maintaining REQUIRED PULSE SPECIFICATIONS the same quality of the pulse shape and its corresponding FOR LOCALIZATION PSD for usual variations of process, supply voltage and In a localization application, several requirements have temperature (PVT) to be set in order to achieve an optimized UWB pulse This paper consists of several sections Section 10 generator The shape of the IR-UWB pulse plays a addresses the required UWB pulse specification as well major role in determining the quality of the pulse generas the evaluation of the minimum transmitted energy ator According to Ref [10], the IR-UWB pulse must be per pulse that a generator should produce in order to a monocycle pulse with a very short pulse width (shorter allow detection by the receiver for short-range localizathan ns) to target a cm precision By applying the monotion applications Section describes the proposed UWB cycle pulse directly to an UWB transmit antenna, it is pulse generator Section gives a detailed explanation transformed into a Gaussian-like pulse This Gaussian-like of the VCRO analysis In Section 5, the results obtained pulse is vital for fitting the PSD inside the regulation of from the simulations and measurements are interpreted theto: FCC mask Another factor that should be taken into Delivered by Ingenta unknown Section 6, presents the experimental result of transmitconsideration is the rate of the pulse repetition frequency ting train of pulses Section investigates the effect of Copyright: American Scientific Publishers (PRF), which has to be in the range of to 500 MHz, PVT variations and subsequent calibrations on the pulse this values of the PRF guarantees the possibility for each generator TX-RX pair to unambiguously distinguish between scattered pulses and direct lign-of-sight (LOS) pulses for any target position within the area and any nodes location.11 1.2 Finally, for the power consumption issue, according to Refs [12, 13], we can consider a low SNR of −10 dB that is still sufficient for good localization design The dependency on the pulse shape and the SNR is extensively studied in Refs [14 and 15] To generate a pulse with minimal power consumption, 1.2 first we have to determine the minimum Energy per pulse that could be transmitted in an indoor area and detected 0 V4-V3(V) 470 mV 400 ps Time (ns) Fig Simulated pulse shape at the output of VCRO (upper curve), at the output of buffer (middle curve) and at the 50 antenna resistance (lower curve) 350 φ2 φ1 –1.2 Time (ns) Fig Typical voltage versus time plots of the VCRO (Fig 1) node (1) (upper curve) and voltage difference between nodes (3) and (4) versus time (lower curve) J Low Power Electron 11, 349–358, 2015 Jazairli and Flandre A 65 nm CMOS Ultra-Low-Power IR-UWB Emitter for Short-Range Indoor Localization Table I Transistor sizes and threshold voltages for each component in the VCRO shown in Figure Inverters and Inverter n-MOS: W = 0.12 m L = 0.1 m Vt = High W = 0.36 m L = 0.1 m Vt = Low p-MOS: W = 0.54 m L = 0.1 m Vt = Low W = 0.12 m L = 0.1 m Vt = High Fig The voltages at different interval nodes of the VCRO (Fig 1) and the current flow in both phase (a) and phase (b) of Figure by the receiver This can be done calculating the transmitted energy while taking into consideration several terms such as the path loss between the transmitter and receiver, Signal to Noise Ratio (SNR) and the level of noise floor From standard telecommunication theory, the received energy can be basically defined by the following equation: Er = Et PL (1) where Er is the received Energy, Et is the transmitted energy and PL is the path loss that can be determined by the following equation for line-of-sight path: PL = · d · fc c (2) p-MOS M0 C1 fF W = 0.8 m L = 0.1 m Vt = Low pulse has been calculated using Eqs (1) and (3) while maintaining the worst case value of path loss (i.e., for 10 m and N0 /2 = 10−19 W/Hz.14 15 ) The minimum Et was found to be 0.48 pJ for SNR = dB and 4.8 pJ for SNR = 10 dB For a short-range indoor application with a m distance, the minimum Et is 0.11 pJ at SNR = dB and 1.1 pJ at SNR = 10 dB These values of the transmitted energy per pulse should be taken into consideration when implementing a very low power pulse generator, since at lower values there is a high probability of losing the transmitted signal PROPOSED UWB PULSE GENERATOR Figure depicts the proposed UWB pulse generator It consists of a voltage controlled ring oscillator (VCRO), cenwhere d is the transmitter receiver distance, fc is theby a buffer and a pulse shaping filter Delivered Ingenta to: unknown tral frequency and c is the speed of light Copyright: American Publishers GHz (as shown in Scientific Using the central frequency fc = 75 3.1 Voltage Control Ring Oscillator VCRO Section 4), the path loss has been calculated using Eq (2) In order to achieve a low-power, low-complexity and to be 45.8 dB for m distance and 65.8 dB for 10 m tunable VCRO, we considered the VCRO configuration distance between the transmitter and the receiver shown in Figure The basis of the VCRO is an impulse The SNR can be determined from the following oscillator consisting of three CMOS inverter stages.8 16 equation: A capacitor C1 and a p-MOS transistor M0 are inserted Er (3) SNR = before the last stage as shown in Figure so as to define N0 /2 the pulse width and the delay between two consecutive where N0 is the noise spectral density in Watts per Hertz pulses The way how C1 and M0 control these paramSeveral values of SNR have been considered and for eters is explained in Section The gate voltage of M0 each of these values, the minimum transmitted energy per (Vcontrol) is used to control the repetition frequency of the pulse generator To guarantee minimum pulse width, the last inverter is designed to have a fast switching transiInverter Inverter 1&2 tion from High-to-Low as compared to the first and second 1.2 450 µm Vout (V) 0.8 100 µm 0.6 0.4 0.2 35 µm 0 0.2 0.4 0.6 0.8 1.2 Vin (v) Fig Inverter DC characteristics (switching curve) for VCCA = 1.2 V J Low Power Electron 11, 349–358, 2015 30 µm Fig Fabricated UWB pulse generator 351 A 65 nm CMOS Ultra-Low-Power IR-UWB Emitter for Short-Range Indoor Localization Amplitude [dBm/MHz] 1000 mV 930 mV Jazairli and Flandre –40 –60 10 Frequency (GHz) 400 ps 500 ps (a) Fig 10 Simulated power spectral density (PSD) of the output pulse (b) Fig Pulse shape at the output of the buffer (a) Measured and (b) Simulated inverters Furthermore, the pulse width will be reduced by scaling CMOS technology A typical waveform at the output of the VCRO is shown in Figure (upper curve) as shown in Figure The inverters here not only isolate the VCRO from the high load of the pulse shaping filter but also provide current driving capability for the pulsed oscillator The first and second inverters in the buffer play a major role in the determination of the pulse width Adding a middle p-MOS transistor in the second inverter as in Ref [18] provides a fast switching transition from Highto-Low as compared to the first inverter in the buffer which reduces the minimum pulse width as shown in Figure (middle curve) The supply voltage VCCB can be further used as a pulse output enable signal FCC Mask –20 –40 –60 800 Measured PW 600 400 Simulated PRF Measured PRF 400 380 Simulated PW 200 100 420 360 150 200 250 300 Pulse Width PW (ps) Pulse Repetition Frequency PRF (MHz) Amplitude [dBm/MHz] 3.2 Pulse Shaping Filter As mentioned in Section 2, a proper filtering is required in order to obtain a Gaussian–like pulse at the output antenna so as to make it compliant with the FCC spectral mask VCRO ANALYSIS AND DESIGN Figure shows the normalized frequency response of the For design optimization purposes, we need to understand Delivered by Ingenta to: unknown pulse shaping filter and the normalized FCC spectral mask the operation scheme of the VCRO and how the capaci17 for indoor UWB devices In our simulators, the values tor C1 and the transistor M0 affect the time delay of the Copyright: American Scientific Publishers of the capacitors Ca = 0.25 pF, Cb = 0.15 pF and inducoutput signal.19 We divide the timing of one pulse into tor L = 2.5 nH are optimized to produce the Gaussian-like two phases and 2, as shown in Figure Also, since waveforms shown in Figure (lower curve) It is worth nodes number (3) and (4) in Figure are essential nodes mentioning that a pulse shaping circuit can also be implewhere the charging and discharging of the capacitor take mented within the UWB transmit antenna and thanks to place, we plot the difference of these voltages along with the low-pass filtering effect the generated pulse will be the output voltage versus time in Figure It is worthwhile shaped by the antenna frequency response Therefore, in noting that phase ( 1) represents the case where V3 is the experimental part of this work, we considered using higher than V4 and hence V3 is the source of the transisthe pulse shaping filter built-in inside the antenna instead tor M0, and phase ( 2) represents the case where V4 of adding a separate pulse shaping filter is higher than V3 and hence V4 becomes the source of transistor M0 as depicted in Figure 3.3 Buffer To ensure that enough current is fed into the capacitors and inductor of the pulse shaping filter, the buffer is designed 340 350 Vcontrol (mV) 10 Frequency (GHz) Fig Measured power spectral density (PSD) of the output pulse 352 Fig 11 Simulated and measured pulse repetition frequency (solid curves) and pulse width (dotted curves) as a function of Vcontrol for VCCA = VCCB = 1.2 V J Low Power Electron 11, 349–358, 2015 A 65 nm CMOS Ultra-Low-Power IR-UWB Emitter for Short-Range Indoor Localization VCRO power consumption 600 1.6 Buffer power consumption Energy consumption 1.2 400 0.8 200 0.4 150 200 Impedance (Ω) Total power consumption 100 (b) 800 Energy consumption per pulse (pJ/Pulse) Average Power consumption (µW) Jazairli and Flandre (a) 100 80 60 40 20 –20 –40 –60 –80 –100 10 Frequency (GHz) control (mV) 250 Fig 14 (a) UWB antenna, (b) Antenna impedance as a function of frequency Vcontrol (mV) Fig 12 Simulation of the power consumption and energy consumption per pulse as a function of Vcontrol for VCCA = VCCB = 1.2 V causing a decrease in VSD and VSG while maintaining VSD > VSG− Vt Thus, the saturation current decreases Phase starts with a high output voltage V1 that subtill it reaches a zero value when V4–V3 =0 which in turn sequently yields a zero voltage at node (2) which in turn makes the 3rd inverter switching from low to high and gives a high voltage at node (3) equal to VCCA Given reinitiates that V4 from the previous period is still low due to the The duration that transistor M0 stays in any of these two delay introduced by M0 and C1, node (3) and node (4) phases depends on the values of Vcontrol, of C1, and of will be the source and the drain of the PMOS transistor the switching thresholds between High-to-Low and LowM0 respectively Moreover, since VSD > VSG– Vt , with to High for the last inverter To approach minimum pulse VSG = VCCA − Vcontrol, and Vt the absolute value of width, we designed the last inverter having a lower logic the threshold voltage, this transistor operates in the satuthreshold as compared to the first and second inverters ration region as long as V4 < Vcontrol+ Vt and its conas shown in Figure Using this analysis, the threshold trol current iD charges the capacitor C1 as shown in the voltage (V T), the width W and the length L of the Figure 5(a) As long as M0 is operatingDelivered in the saturaby Ingenta to: unknown inverters transistors and of M0 are chosen to optimize the tion mode, the charging of the capacitor C1 at a constant sizes of the inverters to get the minimum pulse width as Publishers current raises the voltage at node (4)Copyright: at a steadyAmerican rate as Scientific shown in Table I observed in Figure 5(a) until V4 reaches a value close to The design was made in a 65 nm CMOS technology VCCA This high V4 value switches the last inverter and with low power and general purpose LP/GP transistor gives a new zero output voltage at node In phase 2, the initial zero voltage at node (1) yields (a) a voltage at node (2) equal to VCCA and a zero voltage at node (3) Since node is high from previous phase, 930mV the source and drain of transistor M0 will be at node (4) and node (3) respectively Given that VSD > VSG− Vt , this transistor operates in the saturation mode and its control current iD charges the capacitor C1 as shown in Figure 5(b) However, on the contrary to 1, the charging (b) of the capacitor decreases the source voltage at node (4) 600 1.6 400 1.2 0.8 200 0.4 1000 150 200 250 Energy consumption per pulse (pJ/Pulse) Average Power consumption (µW) 350mV (c) 16mV Vcontrol (mV) Fig 13 Measured power consumption and energy consumption per pulse as a function of Vcontrol for VCCA = VCCB = 1.2 V J Low Power Electron 11, 349–358, 2015 Fig 15 (a) The signal transmitted from the pulse generator through the antenna, (b) the received signal at cm, (c) the received signal at 100 cm 353 A 65 nm CMOS Ultra-Low-Power IR-UWB Emitter for Short-Range Indoor Localization 400 Jazairli and Flandre 1.2 0.8 Theoretical received amplitude 300 Voltage (V) Amplitude (mV) Measured received amplitude 200 0.6 0.4 100 500 ps 0 50 100 150 200 Time (s) Distance (cm) Fig 18 Zoomed-in output waveform sensitivity using Monte-Carlo simulation Fig 16 The measured received amplitude (solid line) and theoretical received amplitude (dotted line) versus distance a special 50 RF probe to the output buffer load to guarantee minimum resistance and capacitor effect from property.20 A process called LP/GP Mix is available and the cables and pads Using the 16 GHz analog bandemploys Low Power and General Purpose devices on the width Agilent DSO-X91604A digital sampling oscillosame chip The advantage of using such 65 nm CMOS scope, we measured the pulse shape shown in Figure 8(a) process is the high performance, low power consumption at the output First, we compared the simulated result and the availability of multi threshold voltages LP devices using the ELDO circuit simulator with the actual device were used for the pulse generator to minimize power conoutput sumption, GP devices were used for the buffer for high In Figure 8, the peak-to-peak amplitude at the output of speed pulse integrity The capacitor C1 was made using the buffer is 930 mV for the measured result while it is n-MOS transitors that is placed inside an NWell so that V for the simulated result The pulse width is about the bottom plate is all N type beneath the poly Figure 500 ps for the measured and 400 ps for the simulated shows the fabricated pulse generator It is Delivered to be notedby that Ingenta to: unknown result Moreover, it is worth mentioning that the signal Copyright: Publishers the pulse shaping filter was not fabricated on chip American in order Scientific shapes corresponding to other values of Vcontrol are simto validate the CMOS emitter separetely and study whether ilar to the ones shown in Figure The measured spectra an adequate antenna can replace the pulse shaping circuit of the output impulse train are shown in Figure 9, while Therefore, all the measurement results in the next section the simulated power spectral density (PSD) is shown in are done without the pulse shaping circuit Figure 10 Given the minimal emitted pulse energy, PSD is always lower than −40 dBm/MHz, which makes it com5 MEASUREMENT RESULTS AND pliant with the FCC mask for all frequency band It is ANALYSIS important to mention that this spectra result is obtained 5.1 Impulse Shape without connecting the pulse shaping circuit Here, the The measurements were realized by connecting the 65 nm UWB antenna parameters work as a pulse shaping circuit and cut the spectra at low frequency making it comply die on a probe station using DC decoupled probes for with the FCC mask the power supply and Vcontrol, as well as connecting (b) 1200 500 VDD=1.2V, T=25°c Pulsewidth (ps) Pulse repetition frequency (MHz) (a) 800 400 100 400 300 200 100 150 200 250 300 350 400 450 TT T FF F SS S S SF F FS Me Measured Vcontrol (mV) Fig 17 Simulation of (a) Pulse repetition frequency versus Vcontrol, (b) Pulse width at Vcontrol = 100 (mV) for different process corners compared with measurements 354 J Low Power Electron 11, 349–358, 2015 Jazairli and Flandre A 65 nm CMOS Ultra-Low-Power IR-UWB Emitter for Short-Range Indoor Localization Pulse repetition frequency (MHz) from 720 W for a pulse repetition frequency of 700 MHz to 118 W for a pulse repetition frequency of 98 MHz at 1.2 V supply voltage In terms of energy consumed per 600 pulse, the pulse width corresponds to an increase from 250 32 pJ to 1.2 pJ as Vcontrol increases from 100 to 250 mV 248 246 31 400 244 30 as shown in Figure 12 The measured results shown in 242 29 3.2 28 Figure 13 confirm the trends and orders of magnitude with 2.8 27 200 process deviations The power consumption including the buffer stage is decreased from 521 W for a pulse repeti0 tion frequency of 450 MHz to 82 W for a pulse repetition 200 300 400 100 frequency of 100 MHz at 1.2 V voltage supply In terms of Vcontrol (mV) energy consumed per pulse, this corresponds to an increase Fig 19 Sensitivity of the pulse repetition frequency versus Vcontrol from 1.1 pJ to 1.5 pJ as Vcontrol increases from 100 mV to 250 mV as shown in Figure 13 Regarding the driven energy per pulse to the 50 load, 5.2 Pulse Frequency and Pulse Width this corresponds to an increase from 0.75 pJ to 0.9 pJ as Our UWB pulse generator further provides a tunable pulse Vcontrol increases from 100 to 250 mV, which implies that repetition frequency In Figure 11, for supply voltages approximately 60–65% of the energy consumed is driven VCCA and VCCB set to 1.2 V, and for typical proto the antenna As explained in Section 2, these values of cess conditions, the simulated pulse frequency decreases energy per pulse are the minimum values that the pulse from 700 to 50 MHz as the control voltage increases generator must transmit in order to be detected by the from 100 mV to 350 mV The pulse width (red dotted receiver curve in Fig 11) varies slightly when the pulse frequency Finally, it is important to mention that we can stop the decreases, from 350 ps at 700 MHz to 420 ps at 10 MHz output pulse emission at any time by either applying a As to the measured result (shown in Fig 11), it validates zero voltage on VCCB, or by applying a voltage higher the controelability of the transmitter The pulse frequency than 400 mV on Vcontrol By applying such voltage, the decreases from 450 MHz to MHz as the control volttransistor M0 will not operate in on regime anymore, so age increases from 100 mV to 350 mV The pulse width Delivered by Ingenta to: unknown no oscillation can take place (the black dotted curve in Fig 11) varies slightly when Scientific Copyright: American Publishers 699 697 695 693 691 689 800 the pulse frequency decrease, from 495 ps at 450 MHz to 410 ps at MHz The quantitative difference between the simulated and measured result are due to the fact that our circuit operates closer to the slow process corner than to the simulated typical process corner as explained in Section 5.3 Power and Energy Consumption The total power consumption of the transmitter sums up the VCRO and buffer In Figure 12, the simulated power consumption dominated by the buffer stage is decreased TRANSMISSION OF PULSES We next connected the pulse generator with the UWB antenna designed at UCL21 shown in Figure 14(a), and we transmitted the signal from the pulse generator through a paired emitter and received antennas so as to study the received signal by using a Digital Sampling Oscilloscope The variation of the UWB antenna impedance with respect to the frequency is shown in Figure 14(b) The upper blue curve represents the real resistance value of the antenna By taking a look at our operating bandwidth (a) (b) –40 VDD=1.2V,Process:TT Normalized PSD (dB) 800 700 600 –20 500 400 300 At 120°C At 25°C At–40°C –40ºC 25ºC 120ºC 200 100 –40 Frequency (GHz) Fig 20 –40ºC 25ºC 120ºC 10 Pulse width (ps) Pulse Repetition Frequency-PRF (MHz) Normalized power spectral density (PSD), (b) Pulse width and PRF of the output pulse simulated at different temperatures J Low Power Electron 11, 349–358, 2015 355 A 65 nm CMOS Ultra-Low-Power IR-UWB Emitter for Short-Range Indoor Localization Jazairli and Flandre Table II Measured results which is between 2.5 GHz and GHz, we find that the resistance varies between 20 and 70 The lower red Process technology 65 nm CMOS curve in Figure 14(b) represents the imaginary part of the Supply voltage VCC = 1.2 V Pulse frequency 450 MHz to MHz impedance, it varies between −20 and 20 in our Power consumption 521 W to 82 W operating frequency range It is worth mentioning that the Pulse width 495 to 503 ps negative value represents a capacitive reactance (1.3 pF at Frequency band 1–7 GHz X = −20 ) while the positive value represents an inductive reactance (10 nH at X = 20 It is notable that in Section we took into consideration these values as pulse shaping circuit and the antenna as well as minimizwell as the extra capacitance and resistance values that are ing the parasitics from the cables in order to reduce the added to the circuit from the cables and the instruments energy losses while simulating our design in order to reach an accurate comparison between the simulated and the measured PVT VARIATIONS result The control voltage is set to obtain a 100 MHz pulse The pulse generator of Figure is examined under Process, repetition frequency The pulse generator generates the Voltage and Temperature (PVT) variations train of pulses shown in Figure 15(a) at the input of In Figure 17(a), the results of corner simulations are the UWB antenna The received signal is shown in shown for an input control voltage Vcontrol varying Figures 15(b), (c) The peak to peak amplitude is around between 100 and 500 mV It is observed that the SF (Slow 350 mV for cm distance between the transmitted and NMOS, Fast PMOS) and FF (Fast NMOS, Fast PMOS) received antenna, while it is 16 mV for 100 cm discorners provide a very high repetition frequency compared tance between the antennas The drop in voltage between to the other cases, which mean that with fast PMOS we Figures 15(a)–(c) is due to the cable losses between the obtain fast repetition frequency This is expected since the pulse generator and the antenna as well as due to the disrepetition frequency is directly proportional to the phase tance In Figures 15(b) and (c), we can easily recognize (as explained in Section 4) and M0 in which the PMOS the effect of the UWB antenna, where the design of the transistor plays the major role for the duration of phase antenna converts the simple pulse to a monocycle impulse from Figure 17, we can see that the measurement Delivered by Ingenta2.to:Also unknown shape, giving the output pulse the necessary shape to make results fall between TT (Typical NMOS, Typical PMOS) American Publishers it comply with FCC mask In FigureCopyright: 16, the solid curve Scientific and SS (Slow NMOS, Slow PMOS) corners represents the measured received amplitude as a function For a localization application, which is our target, the of the distance between the antennas The dotted line repmaximum required pulse frequency is up to 200 MHz In resents the simulated receiving amplitude as directly proFigure 17, we can observe that all the corners meet the portional to 1/d, where d is the distance between the requirements for localization within the range of 200 MHz antennas This was done because ideally the amplitude A Monte Carlo simulation of 50 runs around typical should decrease in a ratio of 1/d as a function of distance process (TT) parameters is done to estimate the system From the two curves in Figure 16 we observe that the sensitivity to device mismatch Figure 18 shows a zoomedmeasured curve follow a trend very close to the theoretical in version of the output waveform sensitivity The output curve calculated for ideal propagation It is important to signal shows a reasonable timing difference but not for note that a bigger range can be obtained by optimizing the amplitude or pulse width as a result of device mismatch (a) (b) Process:TT, T=25°c Output voltage on 50 Ω (V) 800 1V 1.1V 1.2V1.3V 1.4V 700 600 500 400 1V 1.1V 1.2V1.3V 1.4V 300 200 100 VCCA,VCCB (V) Pulse width (ps) Pulse Repetition Frequency-PRF (MHz) Fig 21 (a) Simulated output voltage, (b) Pulse width and PRF at different supply voltages 356 J Low Power Electron 11, 349–358, 2015 Jazairli and Flandre A 65 nm CMOS Ultra-Low-Power IR-UWB Emitter for Short-Range Indoor Localization Table III Comparison with previously reported pulse generators Technology 0.8 Si/SiGe [3] 0.18 m CMOS [4] 90 nm CMOS [5] 0.18 m CMOS [6] 0.18 m CMOS [7] 90 nm CMOS [22] 0.18 m CMOS [23] 65 nm CMOS [This work] Energy consumption per pulse (pJ/pulse) Peak amp (mVpp) Pulse width (ns) Pulse type Band (GHz) Active die area (mm2 ) 80 26 39 65 52 20 1.1–1.5 360 533 595 300 200 414 200 350 04 04 38 09 96 05 Gaussian 5th order Gaussian NA Gaussian Gaussian NA Monocycle Gaussian monocycle 5–9 3–10.6 NA 0–8 3–10 3–4.8 3–5 1–7 32∗ NA NA 026 16 0015 08 0010 variations Figure 19 shows the repetition rate sensitivity References Revision of part 15 of the Commission’s Rules Regarding UWB with the variation of device mismatch It can be easily Transmission System, ET Docket 98-153, Federal Communications seen that the difference in pulse frequency is very small Commission (2002) and can be neglected www.tagent.com The PSD results at different temperatures are shown D Lin, B Schleicher, A Trasser, and H Schumacher, Si/SiGe HBT in Figure 20(a) The −10 dB bandwidth at −40 C is UWB impulse generator tunable to FCC, ECC and Japanese spectral masks, IEEE Radio and Wireless Symposium (RWS), Phoenix, 4.2 GHz which is from 2.2 to 6.6 GHz, while at 120 C Arizona, USA (2011), pp 66–69 the bandwidth becomes 5.2 GHz which is from 2.2 to X Wang, S Fan, B Qin, L Lin, Q Fang, H Zhao, H Tang, 7.4 GHz Figure 21(a) shows different output voltage corJ Liu, Z Shi, A Wang, L Yang, and Y Cheng, A 0.05 pJ/presponding to a variation of the supply voltage VCCA = mV 5th-derivative pulse generator for full-band IR-UWB transceiver VCCB The peak-to-peak amplitude across the 50 outin 0.18 m CMOS, IEEE Radio and Wireless Symposium (RWS), Phoenix, Arizona, USA (2011), pp 70–73 put load slightly decreases when the supply voltage is K K Lee, O Naess, and T S B Lande, A 3.9 pI/pulse differdecreased to 1.1 V, and slightly increases when the supply ential IR-UWB pulse generator in 90 nrn CMOS, IEEE Microelecvoltage is increased to 1.3 V As shown if Figures 20(b) tronics and Electronics (PrimeAsia 2011), Macau, China (2011), Delivered Ingenta to: and 21(b) the difference caused by the variation of by tempp unknown 115–118 perature and voltage on the pulse repletion frequency and L B Leene, S Luan, and T G Constandinou, A 890fJ/bit UWB Copyright: American Scientific Publishers transmitter for SOC integration in high bit-rate transcutaneous biopulse width is very small and would have a negligible 10 implants, IEEE International Symposium on Circuits and Systems effect in applications such as localization CONCLUSION In conclusion, an ultra-low-power frequency-tunable UWB pulse generator has been reported in this paper The pulse repetition frequency varies from 450 MHz to MHz and the power consumption varies from 521 W to 82 W for VCCA = VCCB = 1.2 V when Vcontrol varies from 100 mV to 250 mV The energy consumed per pulse increase from 1.1 pJ to 1.5 pJ, this is the minimum energy per pulse that a pulse generator can transmit so that to be detected by the receiver in a short-distance indoor applications Measured results are summarized in (Table II) and very favorably compare to state-of-the art (Table III) in terms of low energy consumption for achieved pulse peak amplitude, short pulse width, large frequency band and small active die area Acknowledgment: The authors would like to thank Professor Luc Vandendorpe and Dr Achraf Mallat for their kind suggestions and help, Professor Christophe Craeye and Dr Farshad Keshmiri for the design and the fabrication of UWB antenna, Pascal Simon for the assistance with measurements in the WELCOME lab (Wallonia Electronics and Communications Measurements) J Low Power Electron 11, 349–358, 2015 (ISCAS), Beijing, China (2013) M Shen, Y.-Z Yin, H Jiang, T Tian, and J H Mikkelsen, A 3–10 GHz IR-UWB CMOS pulse generator with mW peak power dissipation using a slow-charge fast-discharge technique IEEE Microwave and Wireless Components Letters 24, 634 (2014) W Tang, A G Andreou, and E Culurciello, A low-power silicon-on-sapphire tunable ultra-wideband transmitter, IEEE International Symposium on Circuits and Systems (ISCAS 2008), Seattle, Washington, USA (2008), pp 1974–1977 A Mallat, P Gerard, M Drouguet, F Keshmiri, C Oestges, C Craeye, D Flandre, and L Vandendorpe, Testbed for IR-UWB based 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Wireless Components Letters (MWCL) 19, 83 (2009) G V Fierro and G E Flores-Verdad, A CMOS low complexity gaussian pulse generator for ultra wideband communications, IEEE 19 20 21 22 23 Jazairli and Flandre International Midwest Symposium on Circuits and Systems (MWSCAS 2009), Cancun, Mexico (2009), pp 70–73 M A K Jazairli and D Flandre, Low power pulse generator as a capacitive interface for MEMS applications, IEEE Ph.D Research in Microelectronics and Electronics (PRIME 2009), Cork, Ireland (2009), pp 312–315 F Arnaud, Low cost 65 nm CMOS platform for low power and general purpose applications, Symp VLSI Tech., Los Angeles, USA (2004), pp 10–11 F Keshmiri, R Chandra, and C Craeye, Design of a UWB antenna with stabilized radiation pattern, IEEE AP S/USNC/URSI International Symposium, San Diego, USA (2008), pp 1–4 K K Lee, M Z Dooghabadi, H A Hjortland, O Ncess, and T S Lande, A 5.2 pJ/pulse impulse radio pulse generator in 90 nm CMOS, IEEE International Symposium on Circuits and Systems (2011), pp 1299–1302 M J Zhao, B Li, and Z H Wu, 20-pJ/pulse 250 Mbps lowcomplexity CMOS UWB transmitter for 3–5 GHz applications IEEE Microw Wireless Compon Lett 23, 158 (2013) Mohamad Al Kadi Jazairli Mohamad Al Kadi Jazairli received a B.S degree in Electrical Engineering from Beirut Arab University (BAU), Beirut, Lebanon, in 2005, and a M.S degree in Molecular Electronics and System Design from Linköping University, Linköping, Sweden, in 2008 Since then he joined the Institute of Information and Communication Technologies, Electronics and Applied Mathematics (ICTEAM), at Université catholique de Louvain (UCL), Louvain-La-Neuve, Belgium, where he is currently pursuing his doctoral studies His research interests are in the field of ultra-low-power analog circuits, UWB communication, RFID and sensor design Denis Flandre Delivered by Ingenta to: unknown Denis Flandre Denis Flandre (M’85–SM’03) received the M.S degree in Electrical Engineering, the Ph.D degree and the Research Copyright: American Scientific Publishers Habilitation from the Université catholique de Louvain (UCL), Louvain-la-Neuve, Belgium, in 1986, 1990 and 1999, respectively His doctoral research was on the modelling of Silicon-on-Insulator (SOI) MOS devices for characterization and circuit simulation, his Post-doctoral thesis on a systematic and automated synthesis methodology for MOS analog circuits Since 2001, he is full-time Professor at UCL He is currently involved in the research and development of SOI MOS devices, digital and analog circuits, as well as sensors and MEMS, for special applications, more specifically high-speed, low-voltage low-power, microwave, biomedical, radiationhardened and high-temperature electronics and microsystems He has authored or co-authored more than 900 technical papers or conference contributions He is co-inventor of 11 patents He has organized or lectured many short courses on SOI technology, devices and circuits in universities, industrial companies and conferences He has received several scientific prizes and best paper awards He has participated or coordinated numerous research projects funded by regional and European institutions He has been a member of several EU Networks of Excellence on High-Temperature Electronics, SOI technology, Nanoelectronics and Micro-nano-technology Professor Flandre is a co-founder of CISSOID, a spin-off company of UCL focusing on SOI and high-reliability integrated circuit design and products He is scientific advisor of two other UCL start-ups : INCIZE (Semiconductor characterization and modeling for design of digital, analog/RF and harsh environment applications) and e-peas (Energy harvesting and processing solutions for longer battery life, increased robustness in all IoT applications) He is an active member of the SOI Industry Consortium and of the EUROSOI network He is an IEEE Senior member 358 J Low Power Electron 11, 349–358, 2015