Linear amplification using nonlinear devices and inverse sine phase modulation

• US 3,927,379 A
• Filed: 01/08/1975
• Issued: 12/16/1975
• Est. Priority Date: 01/08/1975
• Status: Expired due to Term

• Current Assignee: Anthony Joseph Jr. Rustako, Donald Clyde Cox, Douglas Otto John Reudink, Rollin Edward Langseth
• Original Assignee: Anthony Joseph Jr. Rustako, Donald Clyde Cox, Douglas Otto John Reudink, Rollin Edward Langseth
• Inventors: Cox, Donald Clyde, Rustako, Anthony Joseph Jr., Langseth, Rollin Edward, Reudink, Douglas Otto John
• Primary Examiner(s): Rolinec, R. V.
• Assistant Examiner(s): Dahl, Lawrence J.
• Application Number:
  US05/539,263
• Time in Patent Office: 342 Days
• Field of Search: 330/10,116,117,124R,149
• US Class Current: 330/10
• CPC Class Codes: H03F 1/0294 using vector summing of two or more constant amplitude phase-modulated signals
• CPC Class Codes: H03F 1/3241 using predistortion circuits H03F1/3211, H03F1/3217 take precedence
• CPC Class Codes: H03F 3/245 with semiconductor devices only

Abstract

A linear amplification providing a replica of an input signal having amplitude variations is accomplished at frequencies and power levels for which linear gain elements are not available. Linear amplification is provided by separating an original bandpass input signal into two components, one of which is a constant amplitude sinusoidal component and the other of which is a low-pass envelope signal. The envelope signal is processed to produce both an inverse sine, phase modulated signal and the complex conjugate of the modulated signal. The phase variations of the modulated signal and of its complex conjugate are proportional to the inverse sine of the envelope. The modulated signal and its complex conjugate are each separately mixed with the constant amplitude sinusoidal signal to produce two constant amplitude signals which are filtered and amplified by either linear or nonlinear devices. The amplified filtered resultants are combined to produce a linearly amplified replica of the original bandpass input signal.

Claims

1. Apparatus for bandpass amplifying an input signal having amplitude and phase variations comprising:

means for producing from the input signal a constant amplitude component and a low-pass envelope signal;

means for processing the envelope signal to produce a constant amplitude signal whose phase variations are proportional to the inverse sine of the envelope signal;

means for generating a complex conjugate signal of the constant amplitude signal from the constant amplitude signal;

first means for mixing the complex conjugate signal with the constant amplitude component to produce a first mixed output;

second means for mixing the constant amplitude signal with the constant amplitude component to produce a second mixed output; and

means for combining the mixed outputs to produce an amplified replica of the original input signal.

2. Apparatus as described in claim 1 wherein said means for producing a constant amplitude component and a low-pass envelope signal includes a limiter and an envelope detector.

3. Apparatus as described in claim 1 wherein said means for combining includes means for bandpass filtering the two mixed outputs and means for amplifying the filtered resultants.

4. Apparatus for bandpass amplifying an analog input signal having amplitude and phase variations comprising:

means for producing from the input signal a constant amplitude component and a low-pass envelope signal;

means for processing the envelope signal to produce a constant amplitude signal whose phase variations are proportional to the inverse sine of the envelope signal;

means for generating a complex conjugate signal of the constant amplitude signal from the constant amplitude signal;

first means for mixing the complex conjugate signal with the constant amplitude component to produce a first mixed output;

second means for mixing the constant amplitude signal with the constant amplitude component to produce a second mixed output;

means for bandpass filtering each mixed output to produce two filtered resultants;

means for amplifying each filtered resultant to produce two amplified resultants; and

means for combining the two filtered resultants to produce a linearly amplified replica of the original bandpass input signal.

5. Apparatus as described in claim 1 wherein said means for processing the envelope signal is an inverse sine phase modulator comprising:

first means for applying a first reference sinusoidal signal as an input to said modulator;

second means for applying a variable amplitude envelope signal to said modulator;

first means for linearly modulating the reference input signal with the variable amplitude envelope signal to produce a first modulated output;

a summer producing a summed signal output;

means for linearly detecting the summed signal to produce a detected envelope;

second means for linearly modulating the first modulated output with the detected envelope to produce a second modulated output;

means for applying a second reference signal in phase quadrature with the second modulated output to said summer;

means for summing the sEcond modulated output and the second reference signal to produce a summed signal which is applied to said means for linearly detecting a summed signal, said summed signal also being applied to a limiter which produces the output of the inverse sine phase modulator, said output having a phase proportional to the inverse sine of the variable amplitude envelope signal.

6. A device as described in claim 4 wherein said means for processing the envelope signal is an inverse sine phase modulator comprising:

means for applying an input envelope signal to the modulator;

a summer producing an output;

means for applying a reference signal and a modulated signal in phase quadrature to said summer;

means for limiting the output of the summer to produce a signal whose frequency is the same as the reference signal frequency but whose phase is shifted by an amount proportional to the inverse sine of the envelope signal.

7. Apparatus as described in claim 6 wherein said means for applying a reference signal and a modulated signal includes a first means for linearly modulating the reference signal with the envelope signal, a second means for linearly modulating the output of the first linear modulator with a feedback envelope signal derived from said summer output and means for phase shifting inserted between the second means for linearly modulating and said summer.