A 12-Gb/s AC-Coupled FFE TX With Adaptive Relaxed Impedance Matching Achieving Adaptation Range of 35-75Ω Z 0 and 30-550Ω R RX

A 12-Gb/s feed forward equalizing transmitter which automatically adapts to arbitrary impedances of AC-coupled channels and receivers is proposed for the first time. The proposed transmitter detects impedances of the channel and the receiver within 8% and 5% errors, respectively, and adaptively relaxes its impedance matching to maximize eye size at cost of a negligible penalty in signal integrity. In experiment, the proposed transmitter adapted to any combination of a channel impedance of 35-75Ω and a receiver impedance of 30-550Ω while achieving eye size larger than the conventional transmitter with impedance matching. At most, a completely closed eye was increased to 136mV by the proposed transmitter.