Electrical compared to optical at 10 Gb/s in 0.1 mm CMOS

• Optics can have near 3 ´ improvement in total link power for same link loss because optics has no 50 W load and can have lower Tx driver swing

• Projected 10 Gb/s transceiver power dissipation using 0.1 mm CMOS (Vdd 1.1 V, tox = 3 nm, Vth = 0.3 V). Assume 850 nm VCSEL Id = 2 mA, 300 mW, Cd = 300 fF, CE = 0.5. Tx pre-driver and output stage. 400 mV LVDS (bias at Vdd / 2) Tx electrical power includes 50 W parallel load termination. Rx first-stage designed to drive FF.

Link loss total electrical power total optical link power

(power) dissipation dissipation

Tx Rx Load

-5 dB 4.90 + 0.11 + 3.2 = 8.21 mW 2.45 + 0.11 = 2.56 mW

-10 dB 4.90 + 1.11+ 3.2 = 9.21 mW 2.45 + 1.10 = 3.55 mW

0.1 mm CMOS projections based on experience with 0.8, 0.5, 0.35, 0.25 mm CMOS, PECL, LVDS, and VCSEL TX and pin RX circuits operating at greater than 2.5 Gb/s.

See, e.g., B. Madhavan and A. F. J. Levi, Low-power 2.5 Gbps VCSEL driver in 0.5 µm CMOS technology, Electron. Lett. 34, 178-179 (1998) and http://www.usc.edu/alevi

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