J. Gerrits FM-UWB Slide 1 John F.M. Gerrits 1, John R. Farserotu 1, Catherine Dehollain 2, Norbert Joehl 2, Michel Declercq 2. 1 Wireless Communications Section Centre Suisse d’Electronique et de Microtechnique S.A. 2 Electronics Laboratory (LEG), EPFL UWB4SN Workshop Lausanne 4 November 2005 FM-UWB: a constant-envelope UWB communications system for short-range LDR applications

J. Gerrits FM-UWB Slide 2 Motivation for frequency domain approach for low complexity UWB Since the definition of a UWB signal does not specify a particular air interface or modulation scheme, many different techniques may be applicable to a UWB signal. Pulses that have been optimized for radar-like applications have not necessarily the best characteristics for a communiciations system. Realization of low power and fully integrated pulse generation circuits is not trivial. More established modulation schemes may/should be used to generate a UWB signal.

J. Gerrits FM-UWB Slide 3 Short range (1-10m) wireless applications and services for monitoring and control: Home automation Security and alarms Health monitoring Sports training These require: Low cost, low power systems Portable (ideally go anywhere) Robust and reliable Good coexistence with other RF systems Fast access (short synchronization time) Applications for LDR FM-UWB

J. Gerrits FM-UWB Slide 4 FM-UWB features True low complexity system compatible with IC technology Relaxed hardware specs (phase noise, component tolerances) No local oscillator No carrier synchronization CSMA/DAA techniques can enhance performance Antennas are not critical Steep spectral roll-off Robustness to interference and multipath Localization compatibility A GHz COTS-based laboratory prototype exists in our labs Key building blocks already available in Si-Ge, down-scaled transmitter under integration in CMOS.

J. Gerrits FM-UWB Slide 5 FM-UWB principle A high modulation index FM signal modulated by a low-frequency signal (f m ) may be seen as an analog spread spectrum system lowering the power spectral density of the transmitted signal. B RF = 2(  f + f m ) This gives approximately N = 2  f/f mod sidebands of almost equal strength in which no carrier can be distinguished. PSD is lowered by 10 log 10 (  f/f m ) = 28 dB 600 MHz 1 MHz

J. Gerrits FM-UWB Slide 6 FM-UWB transmitter FSK FM

J. Gerrits FM-UWB Slide 7 FM-UWB Spectral properties Good co-existence Best use of spectral mask Dynamic interference mitigation

J. Gerrits FM-UWB Slide 8 FM-UWB receiver

J. Gerrits FM-UWB Slide 9 Wideband FM demodulator This demodulator has been fully integrated in Si-Ge BiCMOS.

J. Gerrits FM-UWB Slide 10 Measured results sensitivity: -46 dBm without LNA -68 dBm with 25 dB LNA (5 m in office environment)

J. Gerrits FM-UWB Slide 11 FM-UWB access schemes A multi-user system may use: FDMA at RF carrier level FDMA at sub-carrier level (TDMA)

J. Gerrits FM-UWB Slide 12 FM sub-carrier techniques FM-UWB exploits sub-carrier FDMA techniques. Users have their individual subcarrier frequency and data rate if required. N MAX = 1 kbps, N MAX = 100 kbps

J. Gerrits FM-UWB Slide 13 Power Consumption Projections SystemSubsystemBlocksCurrent consumption VDD = 1 V TransmitterSubcarrier oscillator DDS 6 DAC 3 Low pass filter RF oscillatorRF VCO (wideband) Output amplifier (wideband) LF ADC LF DAC 1500 < ReceiverReceiver RF front-end LNA (wideband) Wideband FM demodulator Antenna switch Sub-carrier processing Sub-carrier quadr. LO Anti Aliasing Filter Mixers LPF Limiter amplifiers FSK demodulator Common20 MHz Quartz osc. Quartz oscillator mW 7.5 mW

J. Gerrits FM-UWB Slide 14 FM-UWB performance in AWGN Data rate R [kbit/s] SNR RF [dB] PL [dB] d FS [m] processing gain = B RF /B SUB 500 MHz / 2R

J. Gerrits FM-UWB Slide 15 Receiver synchronization time Raw data right instantaneously, bitsynchronizer limited

J. Gerrits FM-UWB Slide 16 Robustness to MB-OFDM UWB signals c) SIR = -10 dB BER < 1x10 -6

J. Gerrits FM-UWB Slide 17 Which IC technology is required? A good CMOS or BiCMOS techno (f T = 100 GHz), low V T and low V DD (1 V), on-chip passives with moderate Q factor. Tx Rx

J. Gerrits FM-UWB Slide 18 IC implementation of the FM-UWB Transmitter in 0.18um CMOS Technology Electronics Laboratory of EPFL Catherine Dehollain (Speaker) Norbert Joehl and Michel Declercq Tel: 0041 (0)

J. Gerrits FM-UWB Slide 19 Principle of the FM-UWB Transmitter 1.25 GHz FSK ModulationFM Modulation FSK Modulation FM Modulation

J. Gerrits FM-UWB Slide 20 Specifications  Sub-carrier oscillator  Frequency range: 0.8 f – 1.2 f with f = 100 kHz to 10 MHz.  Waveform: triangular signal.  External capacitor.  V DD = 1.5V  RF oscillator  Frequency range: from 0.75 GHz to 1.75 GHz.  V DD = 1.5V.

J. Gerrits FM-UWB Slide 21 Building blocks of the UWB Transmitter Relaxation Oscillator Ring Oscillator

J. Gerrits FM-UWB Slide 22 Sub-carrier signal at kHz

J. Gerrits FM-UWB Slide 23 Sub-carrier signal at 8 – 12MHz

J. Gerrits FM-UWB Slide 24 RF signal at 1.25 GHz center frequency At the output of the integrated circuit

J. Gerrits FM-UWB Slide 25 Filtered RF signal at 1.25 GHz center frequency Across the 50 Ohm radiation resistance of the antenna: 3.5 mW

J. Gerrits FM-UWB Slide 26 Current consumption of the building blocks Simulation results in UMC 0.18um CMOS with RF options V DD = 1.5V. Sub-carrier oscillator: 0.2 mA. RF oscillator: 3 mA. Output buffer: 4 mA.

J. Gerrits FM-UWB Slide 27 Layout of the FM-UWB Transmitter in UMC 0.18um CMOS GNDRF-OUTGND VH VL Ibias Osc-en VDD Rv-moy Isub Vcycl Csub Surface: 0.7mm X 0.7mm

J. Gerrits FM-UWB Slide 28 Next steps UMC 0.18um CMOS Techno. Manufacturing of the FM-UWB Transmitter. Test of the FM-UWB Transmitter. 0.13um CMOS or 0.35 um, 0.25 um BiCMOS SiGe Techno. Target: the UWB frequency band (3.1 – 10 GHz) Design of the new FM-UWB Transmitter using: - Digital sub-carrier generation GHz and 6-9 GHz RF oscillator and output stage