A Flexible Energy Detection IR-UWB Receiver for RFID and Wireless Sensor Networks

Transcription

1 6 th IEEE UWB Forum on Sensing and Communications May 5 th 2011, TU Graz, Austria A Flexible Energy Detection IR-UWB Receiver for RFID and Wireless Sensor Networks Qin Zhou, Zhuo Zou, Fredrik Jonsson, Li-Rong Zheng ipack VINN Excellence Center School of Information and Comunication Technology KTH-Royal Institute of Technology, Sweden qinz@kth.se 1

2 From RFID to the Internet of Things Packages with Sensing, Computing, Communication and Positioning capabilities reach to the Internet convergence ipack Application Scenario Who, Where, and How RFID Positioning Sensing Low power and cost systems and circuits Technology Enabler Constraint by limited resources (Power, Cost, Size ) Micro-power from autonomous power scavenging (e.g. 100uW/cm³) ULP Design: uw/mbps for wireless link 2

3 Introducing UWB into RFID Impulse Radio Ultra-Wideband Using very short pulses instead of CW Low power TX, aggressively duty cycled radio High time domain resolution for precise ranging and positioning GHz-BW, large channel capacity and robust against multi-path and multi-access (collisions) But RX is too complex to be employed on RFID tags Solution: UWB/UHF Asymmetrical Links Asymmetrical Traffic loads: uplink dominated Asymmetrical hardware resources UHF downlink (Such as Conventional RFID) Power Low traffic Heavy Traffic UWB-IR uplink Asymmetric Link 3

4 UWB/UHF Hybrid RFID System Hybrid RFID System with Asymmetrical Wireless Link UHF downlink UWB uplink Baseband Logic Radio Tag 1 UHF Wake-up Rx UHF Downlink Reader UHF Tx. IR-UWB Rx MHz reference Protocol Processor and Interface IR-UWB Tx UWB Uplink (This work) Previous Work (ISSCC09): Remote-powered UWB/UHF passive tag Die photograph in UMC 0.18um CMOS Active area less than 1 mm 2 Packaged in QFN 48 package 4

5 Carrier-based or Carrier-less IR-UWB? Possible transceiver architecture for the UWB uplink Carrier-based IR-UWB Local oscillators and mixers are necessary at both the TX side and the RX side, Limited bandwidth (e.g. 500 MHz) at relatively low frequency band, Energy efficient receiver (QAC) can be achieved, but deploying high speed and accurate LO on passive tags is infeasible. Carrier-less IR-UWB Do not require any mixer stage, Large bandwidth is possible (several GHz), Enabling low power low complexity TX, but posing more challenges to the RX design. 5

6 IR-UWB Receiver Design Block diagram of an energy detection IR- UWB receiver Signaling of energy detection scheme (OOK modulation) 6

7 IR-UWB Receiver Design Challenges and targets of the receiver design High sensitivity and low energy consumption Flexibility and reconfigurability to facilitate adaptive link in dynamic circumstances (system capacity, QoS requirement, channel condition) Specification for the proposed reconfigurable receiver Parameters Bandwidth Modulation Pulse Rate Code Length (PG) Integration window length Positioning Accuracy Energy consumption Specification 3.1 GHz 4.8 GHz OOK-DSSS, PPM-TH programmable programmable programmable 30 cm (free space) Sub nj/bit 7

8 Hardware Implementation Architecture of the reconfigurable ED IR-UWB receiver High performance Analog Front-End and Timing-critical Digital Circuit in 90nm CMOS Highly flexible baseband in FPGA 8-bit ADC X 2 Integrator BB Amp. ADC 3-5GHz LNA VGAs Timing Circuitry Baseband Ctrl. (RTC) Ext_clk HSMC Read enable Ctrl_signal 8-bit Baseband_clock Digital Baseband Processing & ToA Estimator Integrator BB Amp. ADC ASIC in UMC 90nm Non-RTC Analog Trimming and Configuration FPGA 8

9 Flexible Back-end Highly programmable timing signal T p : Pulse Repetition Interval t d : Window phase delay t w : Window width PG: Processing gain SS: For symbol level synchronization 9

10 Flexible Back-end Architecture of the programmable timing circuit 900MHz 10

11 Flexible Back-end Enabled receiver operation modes Parameters Pulse Rate Code Length (PG) Integration Window (tw) Min. Width Resolution Min. Phase Resolution Modulation Supported Synchronizations Ranging Flexibilities 512 khz - 33 MHz 1-64 chips (0-18 db) 4.4 ns - Tp 4.4 ns 1.1 ns OOK-DSSS, PPM-TH Max. Search, Binary Search, and Energy offsetbased ToA (MES-SB) 11

12 Die Photo & Measurement Setup Die Photo ASIC PCB & Altera FPGA PA High speed BB and Timing Circuit Band Gap Ref. LNA BB Int. 2 Mult.2 VGA2 BB Int. 1 Mult.1 VGA1 Wideband VGAs UHF Transimitter UHF Transmitter Test Buffer Test Buffer Bias 1.8mm Measurement Setup Spectrum Analyzer Reference Clock UWB Tag Attenuators RX chip & FPGA FPGA RX ASIC UWB Tag SPI and USB Random Data Gen. (a) PC 12

13 Measurement Results Timing signal and integrator output without processing gain Timing signal and integrator output with processing gain Integration Window Integrator Output Integrator Output Symbol Reset 13

14 BER Measurement Results BER versus average RX input power (10 Mb/s, OOK, uncoded) Ideal Implementation Measured Results 12 db Loss Received Power (dbm) Implementation Summary Technology 90 nm CMOS Active Area 1.1 mm 2 Voltage Supply 1 V Bandwidth 2 GHz (3-5 GHz) Max. Data Rate 33 Mb/s LNA Wideband VGA Multiplier Integrator Power Consumption BB Amp. High Speed Digital Total Single Channel Dual-Channel Noise Figure 8.5 db Min. energy/bit 0.5 nj/bit Sensitivity@10Mb/s -79 dbm (BER<10-3 ) 1.5 mw 8.0 mw 2.4 mw 3.1 mw 0.5 mw 0.8 mw 16.3 mw 22.3 mw 14

15 Summary Conclusions ipack vision towards Internet-of-Things Introducing UWB into RFID with asymmetrical wireless link Design and implementation of reconfigurable ED IR-UWB receiver References 1. Majid B. Nejad and et al., A Remote-Powered RFID Tag with 10Mb/s UWB Uplink and -18.5dBm-Sensitivity UHF Downlink in 0.18um CMOS, IEEE International Solid-State Circuits Conference, ISSCC 2009, pp , Feb Zhuo Zou and et al., A Low-Power and Flexible Energy Detection IR-UWB Receiver for RFID and Wireless Sensor Networks, IEEE Transactions on Circuits and Systems I-regular paper. Accepted for publishing. 15

16 6 th IEEE UWB Forum on Sensing and Communications May 5 th 2011, TU Graz, Austria Thank You! A Flexible Energy Detection IR-UWB Receiver for RFID and WSN Qin Zhou, Zhuo Zou, Fredrik Jonsson, and Li-Rong Zheng ipack VINN Excellence Center School of Information and Comunication Technology KTH-Royal Institute of Technology, Sweden qinz@kth.se 16