T. Chalvatzis, University of Toronto - ESSCIRC Outline Motivation Decision Circuit Design Measurement Results Summary

T. Chalvatzis, University of Toronto - ESSCIRC Motivation Low-power, high-speed blocks in CMOS for mm- wave A/D Conversion [Chalvatzis, et al., RFIC2006] Low-power blocks for 40- Gb/s wireline and fiber-optic transceivers in CMOS

T. Chalvatzis, University of Toronto - ESSCIRC Decision Circuit Block Diagram Two latches in Master-Slave configuration Data and clock amplifiers as TIAs Output driver buffers to 50Ω

T. Chalvatzis, University of Toronto - ESSCIRC Conventional Latch Conventional CML latch requires 3 vertically stacked transistors Standard 1.2V supply in 90nm V DS too low for 40 Gb/s speed

T. Chalvatzis, University of Toronto - ESSCIRC Previous Work To operate from lower power supply (<1.2V) Transformer coupling for clock-to-data path [Kehrer, et al., CSICS2004] -> Not broadband due to transformer Remove current sources [Kanda, et al., ISSCC2005] -> Not sufficient for 40Gb/s operation

T. Chalvatzis, University of Toronto - ESSCIRC Proposed Latch Bias at peak-f T current density I BIAS =I peak-fT /2=0.15mA/μm High-V T devices on clock path Low-V T devices on data path For I BIAS =4.5mA and R L =40Ω: ΔV=9mAx40Ω=360mV Total power consumption: 10.8 mW/latch

T. Chalvatzis, University of Toronto - ESSCIRC Retiming DFF – Schematic

T. Chalvatzis, University of Toronto - ESSCIRC Retiming DFF – Schematic Clock must fully switch M1/M2 V DS,M7/8 swings as low as V T (M1/M2) Use high-V T for M1/M2 V DS,M7/8 =V DD -ΔV swing =V T =0.34V

T. Chalvatzis, University of Toronto - ESSCIRC TIA Design Methodology Bias at min noise current density 0.15 mA/μm [Dickson, et al., JSSC Aug 2006] p-MOS active load to increase gain at low V DD Feedback inductor L F resonates out the capacitance at the TIA node L F =500pH designed with two top metals for minimum footprint to obtain high SRF

T. Chalvatzis, University of Toronto - ESSCIRC TIA scaling to 65-nm CMOS TIA BW 3dB 3mA

T. Chalvatzis, University of Toronto - ESSCIRC Fabrication and measurement results of decision circuit

T. Chalvatzis, University of Toronto - ESSCIRC V DD =1.2V Area=600x800μm 2 Circuit fabricated in two different foundries TIA DFFDRIVER CLOCK TREE Decision Circuit – Die Photo

T. Chalvatzis, University of Toronto - ESSCIRC Retiming DFF – Test Setup 40-Gb/s signal generated from 4x10Gb/s streams Solid linesData signals Dashed linesClock signals

T. Chalvatzis, University of Toronto - ESSCIRC Measurements at 30Gb/s FCLK=30GHz, Data Rate=30Gb/s, Trise=7ps JitterRMS,input=1.7psJitterRMS,output=0.5ps Single-ended input with other input terminated to 50Ω Jitter from setup not de-embedded Input (top) Output (Bottom)

T. Chalvatzis, University of Toronto - ESSCIRC Measurements at 30Gb/s vs V DD, T JitterRMS,input=1.7psJitterRMS,input=1.4ps JitterRMS,output=0.7psJitterRMS,output=1.0ps Input (top) Output (Bottom) V DD =1V, T=25 o C V DD =1.2V, T=100 o C

T. Chalvatzis, University of Toronto - ESSCIRC Measurements at 37Gb/s and 40Gb/s JitterRMS,input=1.292psJitterRMS,input=1.403ps JitterRMS,output=1.149psJitterRMS,output=1.396ps Input (top) Output (Bottom) 1.5V

T. Chalvatzis, University of Toronto - ESSCIRC Measurements at 40Gb/s and 1.5V Error-free 508-bit pattern Input (top), output (bottom)

T. Chalvatzis, University of Toronto - ESSCIRC Comparison of high-speed latches RefTechnologyRate (Gb/s) Supply (V) P LATCH (mW) P DEC,CIRC (mW) [3]245-GHz InP HEMT805.7N/A1200 [4]250-GHz InP HBT [8]150-GHz SiGe BiCMOS This work 120-GHz CMOS

T. Chalvatzis, University of Toronto - ESSCIRC Conclusion 90-nm CMOS latch and retimer demonstrated at 37 Gb/s from 1.2 V and 40 Gb/s from 1.5 V supply p-MOS device for low-noise TIA on data and clock path Peak-f T bias and combination of low and high-V T devices in latch allows for 40-Gb/s retiming 1.2-V operation at 40 Gb/s possible if clock path TIA replaced with a CML inverter chain with inductive peaking and source follower

T. Chalvatzis, University of Toronto - ESSCIRC Acknowledgements Nortel Networks for funding support STMicroelectronics and TSMC for chip fabrication ECTI, OIT and CFI for equipment NIT for lab access CMC for CAD tools

T. Chalvatzis, University of Toronto - ESSCIRC Backup Slides

T. Chalvatzis, University of Toronto - ESSCIRC f T of LVT and HVT transistors

T. Chalvatzis, University of Toronto - ESSCIRC Measurements at 30Gb/s (min. input) Input (top) – Output (bottom) 1.2V and 60mV input (13-dB attenuation) Retiming with JitterRMS,input=1.9ps JitterRMS,output=1.7ps

T. Chalvatzis, University of Toronto - ESSCIRC Measurements at 7.5Gb/s (Fclk/4) Input (bottom) – Output (top). 1.2V Retiming with JitterRMS,input=4.2ps JitterRMS,output=2.6ps