Abstract: A digital signal regenerator receives a four-level input signal, amplifies, reshapes, and retimes that signal into a regenerated four-level output signal. A wide range controlled equalizer amplifies and reshapes the four-level input signal into an intermediate signal. A variable all-pass circuit varies the shape of the equalizer's phase characteristic to optimally shape the four-level signal as a function of the maximum amplitude of the four-level input signal. The reshaped four-level signal is retimed and amplified into the regenerated four-level output signal. This enable multiplying the rate at which information is transmitted for a selected pulse rate in the transmission line.

Abstract: A controller includes a pair of field-effect transistors interconnected so that their drain-to-source paths are electrically in a parallel circuit combination. The field-effect transistors have similar characteristics except that their minimum drain-to-source impedances are different from each other. An equivalent impedance of the parallel circuit combination is controlled by the gate-to-source voltages of the field-effect transistors. An input signal having a wide range is applied to a control circuit for producing concurrently different magnitude control signals, each of which is applied across the gate-to-source input of a separate one of the field-effect transistors for controlling its drain-to-source impedance over its most linear operating range.

Abstract: An automatically variable all-pass circuit includes a variable impedance circuit for changing the shape of the phase characteristic of the output signal of the all-pass circuit as a function of the amplitude of the output signal of the circuit.