High frequency generator with FET oscillator - uses difference amplifier as regulator for input stage to minimise supply voltage variations

摘要

An R.F. generator using a field effect transistor as the oscillator stage is designed to provide the oscillator with a supply protected against disturbances. The F.E.T. (4) is coupled as an oscillator with a feedback stage (1) over a coupling capacitor (2) and two resistors (3, 5). The resistor (3) is coupled between the gate electrode and earth. The resistor (5) acts as load resistor of the oscillator and is coupled between the source electrode and ground. The operating voltage (Ve) is connected to a regulating stage (6) that is coupled to the drain electrode of the F.E.T. (4). An isolating amplifier composed of two differencing transistors (9, 11) also provides a regulating amplifier function to minimise the effect of supply voltage variations.