Bidirectional optical transceiver with automatically directional controlling function

A bidirectional optical transceiver with an automatically directional controlling function is designed and implemented in a 0.18 mum CMOS technology. A novel transmission envelope detector functions as the directional controlling block to generate the controlling signals according to the received optical signal. The bidirectional optical transceiver achieves a 3-dB bandwidth of 4.4 GHz and 4 GHz in transmitter (Tx) and receiver (Rx) modes respectively, while the disabled outputs for the Tx or Rx modes are isolated with -19 dB and -17 dB, respectively, from the enabled inputs.