A 4Gb/s/link Differential Bidirectional Serial Interface with Self-Diagnosis

A bidirectional, differential interface operating at 4Gb/s/link is presented. Self-diagnosis mode with on-chip BER measurement technique is implemented. The transceiver includes 4-tap Tx-FIR, and Rx linear equalizer of improved area efficiency and 25㏈ peak gain. Sampling timing at I/Os can be adjusted with 4ps resolution by the phase interpolation with multi-phase clocks. The 360˚ coverage of input sampling timing and controllable DC offset with the voltage twister enable the extraction of BER-based eye diagrams. This transceiver includes PRBS generation and verification blocks so that link performance can be monitored without external equipments. The test chip with two transceivers and clocking circuits occupies 1㎜ × 1㎜ and consumes 98.1mW from 1.2V supply.