Direct coupled radio frequency (RF) transceiver front end

A communications front end, configured to transmit a transmitted component of a bidirectional communications signal, and to receive a received component of the bidirectional communications signal from a shared medium, comprising:

• a transmission amplifier configured to provide the transmitted component of the bidirectional communications signal to a common connection;
• and
• a reception amplifier, coupled to the transmission amplifier, configured to receive the received component of the bidirectional communications signal from the common connection,
• wherein the transmission amplifier is further configured to provide the transmitted component of the bidirectional communications signal upon receipt of a first amplifier bias from the common connection and a transmission bias at an input of the transmission amplifier to cause the transmission amplifier to operate in the transmit mode of operation when the transmission bias is less than the first amplifier bias, and
• wherein the reception amplifier is further configured to provide the received component of the bidirectional communications signal upon receipt of a second amplifier bias from the common connection and upon receipt of a reception bias at an output of the reception amplifier to operate in the reception mode of operation when the reception bias is greater than the second amplifier bias, and
• wherein the transmission amplifier comprises:
• a first stage configured to receive the transmission bias at its respective input and a first constant current bias at its respective output;
• and
• a second stage configured to receive the first constant current bias at its respective input and at least one of the first amplifier bias and the second amplifier bias at its respective output;
• wherein, the transmission bias is less than the first constant current bias and the first constant current bias is less than the first amplifier bias during transmission, and
• wherein the reception amplifier comprises:
• a third stage configured to receive at least one of the first amplifier bias and the second amplifier bias at its respective output and a second constant current bias that is greater than the first amplifier bias at its respective output, and
• a fourth stage configured to receive the second constant current bias that is less than the reception bias at its respective input and the reception bias at its respective output,
• wherein, the second amplifier bias is less than the second constant current bias and the second constant current bias is less than the reception bias during reception.

A communications front end comprising:

• a transmission amplifier configured to provide a transmitted component of a bidirectional communications signal in a transmit mode of operation;
• a reception amplifier configured to provide a received component of the bidirectional communications signal in a receive mode of operation;
• and
• one or more bias networks configured to:
• provide a first amplifier bias to a common connection between the transmission amplifier and the reception amplifier, a transmission bias to an input of the transmission amplifier during the transmit mode of operation or a second amplifier bias that is less than the first amplifier bias to the common connection, and a reception bias to an output of the reception amplifier during the receive mode of operation, and
• cause the transmission amplifier to operate in the transmit mode of operation when the transmission bias is less than the first amplifier bias and the reception amplifier to operate in the reception mode of operation when the reception bias is greater than the second amplifier bias,
• wherein the transmission amplifier comprises:
• a first stage configured to receive the transmission bias at its respective input and a first constant current bias at its respective output;
• and
• a second stage configured to receive the first constant current bias at its respective input and at least one of the first amplifier bias and the second amplifier bias at its respective output;
• wherein, the transmission bias is less than the first constant current bias and the first constant current bias is less than the first amplifier bias during transmission, and
• wherein the reception amplifier comprises:
• a third stage configured to receive at least one of the first amplifier bias and the second amplifier bias at its respective output and a second constant current bias that is greater than the first amplifier bias at its respective output, and
• a fourth stage configured to receive the second constant current bias that is less than the reception bias at its respective input and the reception bias at its respective output,
• wherein, the second amplifier bias is less than the second constant current bias and the second constant current bias is less than the reception bias during reception.