Patent ID: 7222199

Claim:
A circuit comprising: a receiver including an input node to receive a transfer signal, and an output node to pass only the transfer signal from the input node to the output node; and a signal detector connected to the receiver to generate an internal signal based on the transfer signal, wherein the signal detector is configured to hold the internal signal at a first signal level when the transfer signal repeatedly switches between the first signal level and a second signal level, wherein the signal detector is configured to hold the internal signal at the second signal level when the transfer signal stops switching, wherein the transfer signal is transferred to the receiver based on a send signal, wherein the transfer signal repeatedly switches between the first and second signal levels when the send signal has a first selected level of the first and second signal levels, wherein the transfer signal stops switching when the send signal has a second selected level of the first and second signal levels, and wherein the send and internal signals have the same frequency.