Transmitter for signal transmission by pulse code modulation

Claim 1

A DELTA PULSE CODE MODULATOR COMPRISING A SOURCE OF INPUT SIGNALS, A SOURCE OF CONTROL PULSES, A SERIES CIRCUIT COMPRISING FIRST AND SECOND TWO-TERMINAL DEVICES THAT HAVE A SYMMETRIC CURRENT-VOLTAGE CHARACTERISTICS AND THAT EXHIBIT A NEGATIVE DIFFERENTIAL RESISTANCE REGION FOR THE SAME DIRECTION OF CURRENT FLOW THROUGH SAID SERIES CIRCUIT, MEANS APPLYING SAID CONTROL PULSES TO SAID SERIES CIRCUIT FOR PERIODICALLY SHIFTING THE BIAS OF SAID DEVICES TOWARD SAID NEGATIVE DIFFERENTIAL RESISTANCE REGION, OUTPUT CIRCUIT MEANS, BIASING CIRCUIT MEANS, MEANS CONNECTING SAID BIASING CIRCUIT MEANS AND OUTPUT CIRCUIT MEANS TO SAID SERIES CIRCUIT, AND MEANS APPLYING SAID INPUT SIGNALS TO SAID BIASING CIRCUIT MEANS, SAID BIASING CIRCUIT MEANS COMPRISING MEANS FOR APPLYING OPPOSITE POLARITY BIASES TO SAID DEVICES EQUAL TO THE DIFFERENCE BETWEEN THE INSTANTANEOUS INPUT SIGNALS AND THE INTEGRATED SIGNALS APPLIED TO SAID OUTPUT CIRCUIT.