Redriver with output receiver detection that mirrors detected termination on output to input

摘要

A redriver chip is inserted between a transmitter chip and a receiver chip and re-drives differential signals from the transmitter chip to the receiver chip. The redriver chip has switched output termination that switches to a high value to detect far-end termination at the receiver chip, and to a low value for signaling. An output detector detects when the receiver chip has termination to ground and enables switched input termination to provide termination to ground on the lines back to the transmitter chip so that the far-end termination on the receiver chip is mirrored back to the transmitter chip, hiding the redriver chip. An input signal detector detects when the transmitter chip begins signaling and enables an equalizer, limiter, pre-driver, and output stage to re-drive the signals to the receiver chip. The input signal detector also causes the switched output termination to switch to the low value termination for signaling.

主权项

1. A method for operating a repeater to mirror a termination impedance to an input comprising:
providing a connection to a first output termination resistance to an output of the repeater; waiting for a measuring period of time to elapse after connecting the first output termination resistance to the output; sensing the output to detect whether the termination impedance is connected; and when connection of the termination impedance is detected, connecting an input termination resistance to an input of the repeater to mirror the termination impedance.