| 摘要 |
<p>A power line communications amplifier includes a first amplifier (23) which amplifies a transmit signal consistent within a first operating potential range, a second amplifier (52, 59, 61) which provides additional amplification of the transmit signal consistent within a second operating potential range, wherein the second range is larger than the first range, and a transformer (90) which is employed to couple the amplifier transmit signal output by the second amplifier (52, 59, 61) to the power line communications system. A feedback circuit (70, 71, 72) couples the output of the second amplifier (52, 59, 61) to the input of the first amplifier (23) and functions to maintain a low output impedance while the amplifier circuit operates in a transmit mode. Control circuit (14, 40) is coupled to the second amplifier (52, 59, 61) for switching the amplifier circuit from the transmit mode to a receive mode. While in the receive mode, the amplifier circuit presents a relatively high output impedance.</p> |
