Patent Number: 6,166,600

Title: Automatic gain and phase controlled feedforward amplifier without pilot signal

Abstract: A pilotless feed forward distortion reduction system uses phase and gain control based on the phases and amplitudes of combining signals prior to a distortion isolation point to maintain the relationship between the phase and amplitudes of combining signals. For example, the feed forward arrangement receives a signal to be amplified on a main signal path and replicates the signal onto a main signal path and a feed forward path. The signal on the main signal path is applied to a gain & phase circuit. The output of gain & phase circuit is applied to the amplifier whose output comprises the amplified signal and distortion signals produced by the amplifier. A portion of the output of the amplifier is placed on a coupling path and combined at the distortion isolation point with a delayed version of the signal on the second path to isolate the distortion produced from the amplifier. The gain & phase circuit is controlled to adjust the gain and phase of the signal such that the signal at the distortion isolation point is substantially the inverse (equal in amplitude but out of phase) of the delayed input signal on the feed forward path. The control signal appearing on the control path of the gain & phase circuit is derived from the portion of the amplified signal with distortion on the coupling path and the delayed version of the signal on the feed forward path.

Inventors: Myer; Robert Evan (Denville, NJ)

Assignee: Lucent Technologies Inc.

International Classification: H03F 1/32 (20060101); H03F 001/26 ()

Expiration Date: 12/26/2013