US 4,383,222 A · Half-wave signal isolator with compensator means to reduce temperature-dependent effects

Abstract

A signal isolator including a coupling transformer with modulate/demodulate switches in series with the primary and secondary windings. The switches are driven in synchronism by an oscillator. Resonating capacitors are connected in parallel with the transformer windings and tuned to the switch operating frequency to control the flux in the transformer core. A transformer turns-ratio of less than unity introduces a corresponding attenuation, and a following amplifier counteracts that attenuation to produce an output signal at the original level. A return current resistor is connected between the output signal and the transformer secondary to produce a back-flow of current towards the transformer. This current provides for supplying the losses of the coupling circuit in a symmetrical fashion, both from the isolator input and its output, to reduce significantly variations in performance resulting from changes in ambient temperature.

Claims8

Dependent claims

In a signal isolator of the half-wave type comprising a coupling transformer having primary and secondary windings;

first and second switches connected to said transformer windings, respectively, one of said switches serving to modulate a signal applied to the transformer primary and the other serving to demodulate the signal developed at the secondary of said transformer;
means for driving said switches in synchronism at a relatively high frequency;
and output circuit means coupled to said transformer secondary and operable to produce an output signal corresponding to the input signal;
that improvement in such signal isolator comprising:
return current means connected between said output circuit means and said transformer secondary for directing to said transformer secondary a current responsive to said output signal to augment supplying of the losses in the coupling circuitry.

2 more elements

Dependencies are inferred from the claim text.

Half-wave signal isolator with compensator means to reduce temperature-dependent effects

Life of this patent

Half-wave signal isolator with compensator means to reduce temperature-dependent effects

Life of this patent

Abstract

Claims8