A Highly-Scalable Analog Equalizer Using a Tunable and Current-Reusable for 10-Gb/s I/O Links

A 0.0015-mm² 1.28-mW single-branch analog equalizer is demonstrated in 65-nm CMOS for 10-Gb/s input/output links. Instead of using passive inductors that are untunable and unscalable with technologies, gain compensation here is optimized via a tunable and currentreusable active inductor (AI). This AI incorporates a positive-feedback impedance converter with only two MOSFETs and one MOS varactor. Together with the use of: 1) negative Miller capacitors to optimize the pole-zero composition and 2) tunable resistive source degeneration to adjust the low-frequency losses, the analog equalizer recovers an eye-opening rate of minimally 30% up to 10 Gb/s over a pair of 60-cm FR4 microtrip traces. The data Pk-to-Pk jitter is <;24 ps, and the RMS jitter is <;4 ps, over a number of pseudorandom bit sequence patterns (2⁷-1, 2¹⁵-1, and 2³¹-1).