Linear amplification using quantized envelope components to phase reverse modulate quadrature reference signals

• US 3,896,395 A
• Filed: 07/18/1974
• Issued: 07/22/1975
• Est. Priority Date: 07/18/1974
• Status: Expired due to Term

• Current Assignee: Donald Clyde Cox
• Original Assignee: Donald Clyde Cox
• Inventors: Cox, Donald Clyde
• Primary Examiner(s): Kaufman, Nathan
• Application Number:
  US05/489,760
• Time in Patent Office: 369 Days
• Field of Search: 330/53,10 328/156C,149C
• US Class Current: 330/53
• CPC Class Codes: H03F 1/0294 using vector summing of two or more constant amplitude phase-modulated signals
• CPC Class Codes: H03F 1/3223 using feed-forward H03F1/3211 takes precedence
• CPC Class Codes: H03F 3/24 of transmitter output stages

Abstract

Available devices including quadrature detectors, delta coders and nonlinear amplifying devices are used to produce linear amplification of a bandpass analog input signal having amplitude variations. This linear amplification technique is primarily useful at high frequencies. The analog input signal is resolved into two variable amplitude quadrature components, the envelopes of which together contain the total information content of the input. The envelopes are applied to separate delta coders which each produce a delta bitstream whose weighted time average approximates the respective envelope. The constant amplitude delta bitstreams phase reverse (phase shift key) modulate two quadrature reference signals. In one embodiment, nonlinear high level phase reverse modulators are used to produce two high level output signals, which are then summed and bandpass filtered to produce a linearly amplified replica of the original analog input signal. In another embodiment, two output signals from low level phase reverse modulators are each amplified by separate nonlinear amplifiers. The amplified resultants are then summed and bandpass filtered to produce a linearly amplified replica of the original analog input signal. In all embodiments, a decoder feedback loop is required. This loop may be either internal to the delta coder or external and coupled to the linearly amplified replica.

Claims

1. A device for amplifying a high frequency bandpass analog input signal having both amplitude and phase variations and having a given maximum amplitude comprising:

quadrature detector means for producing from the input signal a pair of variable amplitude intelligence containing envelopes each said envelope being derived from different ones of the quadrature signal components of the input signal;

means for producing from each variable amplitude envelope a bitstream approximation whose weighted time average is a replica of the respective envelope;

means for generating two quadrature reference signals of equal amplitude;

means for phase reverse modulating the two quadrature reference signals respectively with ones of the two bitstream approximations to produce two constant envelope signals of Amplitude greater than the maximum amplitude of the input signal;

means for combining the two constant envelope signals to produce a linearly amplified replica of the original analog input signal.

2. A device as described in claim 1 wherein said means for producing the bitstream approximation of each variable envelope is a pair of delta coders.

3. A device as described in claim 2 wherein each delta coder has a decoder feedback loop containing a low-pass filter.

4. A device as described in claim 3 wherein said means for combining includes means for bandpass filtering the two constant envelope signals, said means for bandpass filtering having characteristics equivalent to those of the low-pass filter of the decoder feedback loop of the delta coder.

5. A device as described in claim 1 wherein said means for generating produces two quadrature reference signals each having a maximum amplitude greater than the maximum amplitude of the original input signal, and said means for modulating includes a pair of high level phase reverse modulators.

6. A device as described in claim 1 wherein said means for modulating includes a pair of low level phase reverse modulators which produce two low level constant envelope signals, and an individual amplifier for separately amplifying each of the low level signals.

7. A device as described in claim 1 wherein said means for combining includes a summing device for combining the two constant envelope signals and a bandpass filter for filtering the combination.

8. A device as described in claim 1 wherein said means for combining includes at least one bandpass filter for filtering each of the two constant envelope signals and a summing device for combining the filtered signals.

9. A device as described in claim 1 wherein said means for producing a bitstream approximation includes means for comparing the envelopes of the quadrature components with a signal derived from the linearly amplified replica produced by the combining means.

10. A device for amplifying a high frequency bandpass analog input signal having both amplitude and phase variations and having a given maximum amplitude comprising:

quadrature detector means for producing from the input signal a pair of variable amplitude intelligence containing envelopes each said envelope being derived from different ones of the quadrature signal components of the input signal;

delta coder means for producing from each variable amplitude envelope a bitstream approximation whose weighted time average is a replica of the respective envelope;

means for generating two quadrature reference signals of equal amplitude;

means for phase reverse modulating the two quadrature reference signals respectively with ones of the two bitstream approximations to produce two constant envelope signals;

means for amplifying the two constant envelope signals;

means for combining the two amplified constant envelope signals; and

means for bandpass filtering the combination to produce a linearly amplified replica of the original analog input signal.