Linear amplification using nonlinear devices and feedback

• US 3,909,742 A
• Filed: 08/19/1974
• Issued: 09/30/1975
• Est. Priority Date: 08/19/1974
• Status: Expired due to Term

• Current Assignee: Donald Clyde Cox, Douglas Otto John Reudink
• Original Assignee: Donald Clyde Cox, Douglas Otto John Reudink
• Inventors: Cox, Donald Clyde, Reudink, Douglas Otto John
• Primary Examiner(s): Mullins, James B.
• Application Number:
  US05/498,637
• Time in Patent Office: 407 Days
• Field of Search: 330/21,31,26,28,3R,31,53,84,124R 333/10,11
• US Class Current: 330/84
• CPC Class Codes: H03F 1/0294 using vector summing of two or more constant amplitude phase-modulated signals
• CPC Class Codes: H03F 1/32 Modifications of amplifiers to reduce non-linear distortion by negative feedback H03F1/34
• CPC Class Codes: H03F 1/345 using hybrid or directional couplers
• CPC Class Codes: H03F 3/24 of transmitter output stages
• CPC Class Codes: H04B 3/06 by the transmitted signal

Abstract

Available devices including hybrid combiners, nonlinear amplifying devices, a phase varying device and an attenuator are used to produce a linearly amplified replica of a bandpass analog signal having amplitude variations. An original analog input signal and a feedback signal are applied to a first hybrid combiner which subtracts the feedback signal from the original input signal to produce one of two components of equal amplitude and adds the feedback signal to the original input signal to produce the other component. The components are amplified separately by nonlinear amplifying devices and the amplified components then recombined by a second hybrid combiner which produces two outputs. One output, the difference between the two components, is a linearly amplified replica of the original input signal. The other output, the sum of the two components, is the feedback signal which is applied through a series combination of the phase varying device and the attenuator to the first hybrid combiner.

Claims

1. In apparatus for linearly amplifying a bandpass high frequency analog input signal having amplitude variations, plural amplifying means the characteristic of which is nonlinear as contrasted with the requirement for linearity between input and output;

means for producing from the input signal at least two signal components having constant amplitude but differing in phase;

means for applying said component signals for separate amplification in respective ones of said plural nonlinear amplifying means;

means for recombining the amplified components to produce a linearly amplified replica of the input signal, the replica being the difference of the two amplified components;

said means for recombining also producing a feedback signal, the feedback signal being the sum of the two amplified components; and

said means for producing a pair of components including means for combining the input and the feedback signal.

2. Apparatus as described in claim 1 wherein said means for combining comprises a series arrangement of an attenuator and An adjustable phase varying device which adjusts the phase of the feedback signal to equal that of the original input and adjusts the amplitude of the feedback signal to a desired level.

3. Apparatus as described in claim 1 wherein said means for producing includes a first hybrid combiner and said means for recombining in a second hybrid combiner, each hybrid combiner having two inputs and two outputs, one output being the sum of the two input signals and the other output being the difference of the two input signals.

4. Apparatus as described in claim 1 wherein said means for amplifying includes two nonlinear amplifiers, each amplifying respective ones of the components.

5. In apparatus for linearly amplifying a high frequency bandpass analog input signal having amplitude variations, plural amplifying means the transmission characteristic of which is nonlinear as contrasted with the requirement for linearity between input and output;

means for producing from the input signal at least two signal components having equal amplitude but differing in phase;

means for applying said component signals for separate amplification in respective ones of said plural nonlinear amplifying means;

means for recombining the amplified components to produce a replica of the input signal, said means for recombining also producing a feedback signal; and

means for applying the feedback signal to said means for producing a pair of components.

6. Apparatus as described in claim 5 wherein said means for producing and said means for recombining are a first and second hybrid combiner, respectively, each having two inputs and two outputs, one output being the sum of the two inputs, the other output being the difference of the two inputs.

7. Apparatus as described in claim 6 wherein the feedback signal is the summed output of the means for recombining, and the replica is the difference of the two inputs applied to said means for recombining.

8. Apparatus as described in claim 5 wherein said means for applying includes the series combination of a phase varying device and an attenuator to which is applied the summed output of said means for recombining and from which emanates an output which is one of the two inputs applied to said means for producing.