Linear Amplification by Sampling Techniques: A New Application for Delta Coders

A new technique for linear amplification of envelopevarying bandpass signals using sampling techniques (LIST) and devices having nonlinear input-output relationships is described. Two component signals are produced by phase-reversal modulating two quadrature carriers with two delta-coded low-pass envelopes derived from the quadrature components of a bandpass signal. The component signals either are produced at a high level or are amplified in nonlinear amplifiers. An amplified replica of the input signal results from passively summing and bandpass filtering these two component signals. A laboratory demonstration shows that a LIST amplifier with spurious 40 dB below desired signals in a two-tone test is easily achieved.