Transmitter interface for clock signals - has switch controlled by clock signals connecting DC supply to line transformer

摘要

The transmitter interface, for clock signals, is matched to the transmission line even during the intervals between clock pulses. The clock signal controls a switch that connects a dc supply through to the series combination of a protective resistor and transformer primary. The transformer secondary is coupled to the transmission line (Z); A diode (D1) is connected across the resistor (R1) and the primary. The product of the square of the transformer turns ratio and the resistor value is approx. equal to the transmission line wave impedance. The supply voltage (UB) is such that UB/UD (2Tt/t) - 1, where UD is the diode turn-on voltage, Tt the clocking period and t the duration of a clock pulse.