Component Signal Separation and Recombination for Linear Amplification with Nonlinear Components

LINC is a technique that uses signal processing to produce linear amplification of bandpass signals with grossly nonlinear circuit components. Two important signal-processing functions of LINC are 1) forming two constant envelope phase-modulated signal components from the bandpass input signal and 2) recombining the amplified components to produce an amplified replica of the input signal. Two-tone laboratory tests of a LINC component separator and combiner, not including a limiter and envelope detector, show that, at full output, spurious levels 40 dB below tone level are achievable over a 1-MHz band. Because the laboratory model operated at relatively low frequencies (hundreds of megahertz), scaling up in frequency should result in a LINC with <40-dB spurious over a 10-MHz band. Spurious 30 dB below tone level should be achievable over a bandwidth of 50 to 100 MHz using the same technique of component signal separation. Lower spurious levels or greater bandwidths will require a sin^-1phase modulator that is less sensitive to delay in a feedback loop.