Patent ID: 7689122

Claim:
An optical transceiver comprising: an optical receiver; an optical transmitter; and a signal detect circuit comprising the following: a signal strength measuring differential output linear amplifier having a positive and a negative output terminal; a positive peak detection circuit coupled to the positive output terminal of the linear amplifier, wherein the positive peak detection circuit is configured to generate on its output terminal a positive peak signal that represents a peak magnitude of a peak of a signal received from the positive output terminal of the linear amplifier; a negative peak detection circuit coupled to the negative output terminal of the linear amplifier, wherein the negative peak detection circuit is configured to generate on its output terminal a negative peak signal that represents a peak magnitude of a peak of a signal received from the negative output terminal of the linear amplifier; and a comparison circuit configured, upon power up, to detect when the positive peak signal magnitude has exceeded a first value and when the negative peak signal magnitude has exceeded a second value, wherein the comparison circuit is further configured to thereafter compare an interpolation of the positive peak signal and the negative peak signal with a third value, wherein the comparison circuit is configured to generate a signal representing that no signal is being received at the signal strength measuring differential output linear amplifier if the interpolation is below the third value.