2. T. Chalvatzis, University of Toronto - ESSCIRC 20062 Outline Motivation Decision Circuit Design Measurement Results Summary

3. T. Chalvatzis, University of Toronto - ESSCIRC 20063 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

4. T. Chalvatzis, University of Toronto - ESSCIRC 20064 Decision Circuit Block Diagram Two latches in Master-Slave configuration Data and clock amplifiers as TIAs Output driver buffers to 50Ω

5. T. Chalvatzis, University of Toronto - ESSCIRC 20065 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

6. T. Chalvatzis, University of Toronto - ESSCIRC 20066 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

7. T. Chalvatzis, University of Toronto - ESSCIRC 20067 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

8. T. Chalvatzis, University of Toronto - ESSCIRC 20068 Retiming DFF – Schematic

9. T. Chalvatzis, University of Toronto - ESSCIRC 20069 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

10. T. Chalvatzis, University of Toronto - ESSCIRC 200610 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

11. T. Chalvatzis, University of Toronto - ESSCIRC 200611 TIA scaling to 65-nm CMOS TIA BW 3dB =28GHz @ 3mA

12. T. Chalvatzis, University of Toronto - ESSCIRC 200612 Fabrication and measurement results of decision circuit

13. T. Chalvatzis, University of Toronto - ESSCIRC 200613 P=130mW @ V DD =1.2V Area=600x800μm 2 Circuit fabricated in two different foundries TIA DFFDRIVER CLOCK TREE Decision Circuit – Die Photo

14. T. Chalvatzis, University of Toronto - ESSCIRC 200614 Retiming DFF – Test Setup 40-Gb/s signal generated from 4x10Gb/s streams Solid linesData signals Dashed linesClock signals

15. T. Chalvatzis, University of Toronto - ESSCIRC 200615 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)

16. T. Chalvatzis, University of Toronto - ESSCIRC 200616 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

17. T. Chalvatzis, University of Toronto - ESSCIRC 200617 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) 37Gb/s @ 1.2V40Gb/s @ 1.5V

18. T. Chalvatzis, University of Toronto - ESSCIRC 200618 Measurements at 40Gb/s and 1.5V Error-free 508-bit pattern Input (top), output (bottom)

19. T. Chalvatzis, University of Toronto - ESSCIRC 200619 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 HBT501.520125 [8]150-GHz SiGe BiCMOS432.523288 This work 120-GHz CMOS 37 40 1.2 1.5 10.8 20 130 240

20. T. Chalvatzis, University of Toronto - ESSCIRC 200620 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

21. T. Chalvatzis, University of Toronto - ESSCIRC 200621 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

22. T. Chalvatzis, University of Toronto - ESSCIRC 200622 Backup Slides

23. T. Chalvatzis, University of Toronto - ESSCIRC 200623 f T of LVT and HVT transistors

24. T. Chalvatzis, University of Toronto - ESSCIRC 200624 Measurements at 30Gb/s (min. input) Input (top) – Output (bottom) 30Gb/s @ 1.2V and 60mV input (13-dB attenuation) Retiming with JitterRMS,input=1.9ps JitterRMS,output=1.7ps

25. T. Chalvatzis, University of Toronto - ESSCIRC 200625 Measurements at 7.5Gb/s (Fclk/4) Input (bottom) – Output (top). 7.5Gb/s @ 1.2V Retiming with JitterRMS,input=4.2ps JitterRMS,output=2.6ps