Patent ID: 8098087

Claim:
A method for standby voltage offset cancellation at inputs to a comparator within a receiver channel, comprising: operating a master state machine to power down an input buffer of the receiver channel so as to isolate a first input of a high-frequency comparator from a first high-frequency input signal, and so as to isolate a second input of the high-frequency comparator from a second high-frequency input signal, and so as to isolate a first input of a low-frequency comparator from a first low-frequency input signal, and so as to isolate a second input of the low-frequency comparator from a second low-frequency input signal, such that each of the first and second inputs of the high-frequency comparator and each of the first and second inputs of the low-frequency comparator attains a respective standby voltage level; operating a search state machine to monitor an output signal of the high-frequency comparator and an output signal of the low-frequency comparator; operating the search state machine to program incremental increases in a voltage level on one of the first and second inputs of the high-frequency comparator from a low voltage end of a voltage adjustment range toward a high voltage end of the voltage adjustment range; upon detecting a state transition in the output signal of the high-frequency comparator via the monitoring by the search state machine, operating the search state machine to stop programming the incremental increases in the voltage level on the one high-frequency comparator input such that a final voltage level programmed by the search state machine is retained on the one high-frequency comparator input; operating the search state machine to program incremental increases in a voltage level on one of the first and second inputs of the low-frequency comparator from the low voltage end of the voltage adjustment range toward the high voltage end of the voltage adjustment range; and upon detecting a state transition in the output signal of the low-frequency comparator via the monitoring by the search state machine, operating the search state machine to stop programming the incremental increases in the voltage level on the one low-frequency comparator input such that a final voltage level programmed by the search state machine is retained on the one low-frequency comparator input.