fin 3,896,395  July 22, 1975
 LINEAR AMPLIFICATION USING
QUANTIZED ENVELOPE COMPONENTS TO
PHASE REVERSE MODULATE
QUADRATURE REFERENCE SIGNALS
 Inventor: Donald Clyde Cox, New
 Assignee: Bell Telephone Laboratories,
Incorporated, Murray Hill, N.J.
 Filed: July 18, 1974
 Appl. No : 489,760
 U.S. CI 330/53; 328/149; 328/156;
330/10; 330/124 R; 332/41
 Int. CI.2 H03F3/60
 Field of Search 330/53, 10; 328/156 C,
 References Cited
UNITED STATES PATENTS 3,426,292 2/1969 Seidel 330/53 X
Primary Examiner—Nathan Kaufman
Attorney, Agent, or Firm—David L. Hurewitz
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.
10 Claims, 4 Drawing Figures