Polarity-insensitive signal detect circuit for use with any signal sequence

An optical transceiver comprising:

• a signal detect circuit comprising the following:
• a signal strength measuring linear amplifier having a positive and a negative output terminal, wherein the signal strength measuring amplifier receives an input signal;
• 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 generates a signal representing that the input signal is not being received if the interpolation is below the third value.

An optical transceiver comprising a signal detect circuit comprising:

• 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 to operate in a first operational state 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, the comparison circuit further being configured to operate in a second operational state to determine if a signal is being received at the signal strength measuring differential output linear amplifier by comparing an interpolation of the positive peak signal and the negative peak signal with a third value,
• wherein the comparison circuit comprises logic configured to switch the comparison circuit from the first operational state to the second operational state.