Frequency-Division Bidirectional Communication Over Chip-to-Chip Channels

Frequency division multiple access is applied to bidirectional communication over chip-to-chip links. Frequency division is implemented by dividing the spectrum into low-frequency (dc) and high-frequency (ac) bands using a simple LC filter. The nonidealities that this filter introduces are compensated for with a transmitter/receiver pair that can recover signals in both bands. The receiver uses a dual-path topology that includes hysteresis to recover data from a signal with no dc content. The transmitter is a 6-tap (FIR) pre-emphasis equalizer with variable tap spacing. In simulation, the transmitter and receiver simultaneously communicate error-free at 8 Gb/s over the ac channel and at 500 Mb/s over the dc channel. Measurements shows that the ac and dc signals can be individually recovered and that the two signals occupy distinct frequency bands.