Gated tunnel diode in oscillator applications with high frequency tuning

A gated tunnel diode has been introduced into a wave-guide oscillator circuit and the gate is used to tune the oscillation frequency and to turn the oscillator on and off. Oscillators with oscillation frequencies in the range of 9–22 GHz with a typical oscillator output power about −20 dBm have been fabricated. We found that the output power remains essentially constant over a gate bias range (about −260–200 mV at Vc = 1.0 V in one oscillator), while it rapidly drops to the noise level over a gate bias range of less than 60 mV above or below the threshold, respectively. In the region with constant power, a total frequency tuning of about 30% is achieved. The maximum oscillation frequency, fmax osc, of the gated tunnel diode is set by the tunnel diode and the gate–collector capacitance, and does not depend on the gate–emitter capacitance. This oscillator implementation, in particular, eliminates the need for a separate switch in the realisation of oscillator-based ultra-wide band impulse radios.