A 107pJ/b 100kb/s 0.18μm Capacitive-Coupling Transceiver for Printable Communication Sheet

A 107pJ/b 100kb/s 0.18μm Capacitive-Coupling Transceiver for Printable Communication Sheet L. Liu,. Takamiya, T. Sekitani, Y. Noguchi, S. Nakano, K. Zaitsu, *T. Kuroda, T. Someya and T. Sakurai University of Tokyo *Keio University

Outline Printable Communication Sheet (CS) for Ubiquitous Electronics Low Energy Capacitive Coupling Transceiver for CS (1) Data Edge Signaling to Eliminate Global Clocks (2) DC Power-Free Pulse Detector Experimental Results Summary 2

Ubiquitous Electronics Convenience Safety & Security 1,000~10,000 Electronic devices Healthcare Entertainment Welfare How to communicate effectively? Issues Wireline Immobility Wireless High Power 3

What is Communication Sheet? Enabling multiple electronic objects scattered over the sheet to communicate without physical connections. Infrastructure for the ubiquitous electronics together with the wireless power transmission sheet [2]. 4

Overview of Communication Sheet (CS) Low Cost, Flexible 2D obility μm-scale wireless Wireless meter-scale wireline Security, Unnecessary RF Band Allocation Low Power communication CS enables both mobile and low power communication. 5

Capacitive or Inductive Coupling? Capacitive coupling V Inductive coupling C C RX C s V rx E=CV 2, C=C c C s (C s = 100pF, C c = 50pF) I TX TX L RX V rx k=1 E=LI 2, I=V rx /jωl (L = 10μH) TX Energy (J/bit) 100u 1u 10n 100p Inductive V = 1.8V V rx = 0.6V Capacitive 1p Target (100kbps) 10f 10k 100k 1 10 Frequency (Hz) Capacitive coupling achieves lower energy in CS. 6

Capacitive-Coupling Transceiver in CS TX sheet TX LSI RX sheet RX LSI 75μm 50pF Pad Wireless capacitive coupling between 16 pads Detected position ES Organic emory Data Datab Communication sheet for routing No common ground requires differential signaling. ES switches provides lower parasitic capacitance than the organic FETs. 7

Dynamic Routing in CS 0 1 7 0 1 7 :ES switch :Organic memory 8

Dynamic Routing in CS 0 1 7 0 1 7 :ES switch :Organic memory Arbitrary 2 points are connected via 4 switches. 9

Device Structure of CS 20cm 16 x 16 pads for capacitive coupling 20cm 9.7 mm 3.0 mm 4 pads for TX TX sheet CS is fabricated with printing technology. CS 9 x 8 ES switches for Data 9 x 8 ES switches for Datab 9 x 8 organic nonvolatile memory 8 x 8 coils for position detection 10

Outline Printable Communication Sheet (CS) for Ubiquitous Electronics Low Energy Capacitive Coupling Transceiver for CS (1) Data Edge Signaling to Eliminate Global Clocks (2) DC Power-Free Pulse Detector Experimental Results Summary 11

Data Edge Signaling Datain 0 1 1 1 0 Output of TX Conv [5] (with CLK) Proposed (w/o CLK) V DD V DD /2 0 V DD V DD /2 0 Data Edge Signaling without clock reduces the number of pads for capacitive-coupling and achieves low power. 12

Transmitter for Data Edge Signaling Edge detector Datain Delay VDD/2 Return-to-VDD/2 pulse Data Datab The modulated data is achieved by switching the input data and the output of the V DD /2 generator. 13

Outline Printable Communication Sheet (CS) for Ubiquitous Electronics Low Energy Capacitive Coupling Transceiver for CS (1) Data Edge Signaling to Eliminate Global Clocks (2) DC Power-Free Pulse Detector Experimental Results Summary 14

DC Power-Free Pulse Detector Problems of conv clock-less RX: Large DC power Voltage Data Datab V DD /2 bias A B V DD /2-ΔV bias V DD Out V DD V DD /2 V DD /2-ΔV 0 Logical V TH A Detected B ΔV Time Dynamic logical V TH of the inverter achieves DC power-free pulse detection. 15

Receiver with DC Power-Free Pulse Detector Communication sheet Bias 1 Bias 2 RX Level Shifter Datain TX Data Datab Dataout Bias 1 Bias 2 : V DD /2 generator : (V DD /2 ΔV) generator Bias 1 Bias 2 Pulse detector 16

Simulated RX Waveforms 1.8 Datain (V) 0 1.3 Data (V) Inputs 0.5 of RX 1.3 Datab (V) 0.5 400 I DD of RX (na) 0 0 4 0 1 0 8 12 16 Time(μs) 20 DC power-free pulse detection 17

Data Transition Dependent Power Power consumption (a.u.) 1.0 0.8 0.6 0.4 0.2 Simulated -48.3% TX+RX TX RX 0.0 0 25 50 75 100 Data transition probability (%) For the 50% data transition probability, the power consumption can be reduced by 48.3%. 18

Outline Printable Communication Sheet (CS) for Ubiquitous Electronics Low Energy Capacitive Coupling Transceiver for CS (1) Data Edge Signaling to Eliminate Global Clocks (2) DC Power-Free Pulse Detector Experimental Results Summary 19

Chip icrographs TX RX 39 μm 20 25 μm 45 μm 55 μm 0.7 mm 0.85 mm 0.4 mm 0.4 mm

Performance Summary Technology Supply Voltage Typ Data Rate ax Communication Coupling Capacitive Distance Wireline Alignment Tolerance TX Power RX @100kbps Total Energy per bit TX Core Area RX 0.18μm COS 1.8V 100kbps 8bps 150μm 60cm 7.5mm 9.73μW 0.97μW 10.7μW 107pJ/bit 2475μm 2 975μm 2 21

Capacitive-Coupling Communication on CS TX LSI RX LSI TX pads Capacitive coupling RX pads Datain Communication sheet (Only pads and interconnects) Dataout 0110010101 100kbps 60cm 22

easured Waveforms Datain TX Txout 0 1 0 1 0 1 0 1 1 0 Datain (100kbps) Txout 1.8V 1.8V RX Rxin Rxin 0.5V Dataout Dataout 1.8V 23

Eye Diagram 125ns Eye diagram at maximum data rate of 8bps. 24

ΔV Dependence of RX V DD 2 Pulse detector V DD 2 -ΔV V 1 V DD RX power (μw) 1.6 1.2 0.8 0.4 0 100kbps 0 0.15 0.3 ΔV (V) 0.6 0.4 0.2 inimum detectable RX amplitude(v 1 ) (V) The tradeoff between the power and the RX sensitivity can be tuned by ΔV. 25

ΔV dependence of Displacement Distance (μm) 150 125 100 75 50 25 0 Typical (Equals to 52pF) inimum ΔV (V) 0.300 0.285 0.270 0.255 100kbps 2.5 5.0 7.5 Displacement (mm) For the 75μm distance, the sheet can operate up to 3.75mm displacement. The maximum tolerable displacement was 7.5mm, which corresponds to the 77% of the pad size. 26

Comparison Communication energy per bit (J/bit = W/bps) 10n 1n 100p 10p This work Wireless Impulse UWB [7] Wireline SerDes [6] This work WLAN [9] OFD UWB [8] 1p 0.1 1 10 100 Communication distance (m) 107pJ/bit at 100kbps and 60cm distance. Realizing low-energy feature of wireline with easy-touse feature of wireless. 27

Summary The communication sheet combining the merit of wireless and wireline approaches Achieving both the mobility of wireless communication and the low-power performance of wireline communication. The 100kbps 0.18μm capacitive-coupling transceiver for the communication sheet Low power data edge signaling and DC power-free pulse detector The lowest energy of 107pJ/bit in the wireless communications 28