An X-band nanosecond gunn oscillator

Phase stabilization effect in nanosecond microwave Gunn oscillators

“…This circuit models the waveguide system of a real oscillator (Fig. 3) [12]. To account for the effect of the microwave resonator electric field on the processes in the diode semiconductor structure, the equivalent circuit contained an oscillatory circuit with a resistive load and additional elements fitting the peculiarities of the Gunn oscillator design.…”

“…The load was used to imitate power extraction from the resonator. The parameters of the equivalent circuit were chosen so that microwave oscillation with a carrier frequency of ∼10 GHz was excited at the load [12]. The calculations show that in all cases under study, the microwave oscillation phase is determined by the transition of the semiconductor structure to the mode of negative differential resistance with increasing the modulating voltage pulse during its rise time.…”

Phase stabilization of nanosecond microwave oscillations in Gunn-diode-based oscillators

“…Therefore, at the sec ond stage, we numerically analyzed a GD with an oscillating loop (see Fig. 1) with regard to basic design features of the oscillator's electrodynamic system [16].…”

“…Its basic element is a modulator based on a voltage pulse shaper with a storage capaci tor (C = 12.6 pF), which partially discharges using a DE275 switch transistor. The circuit diagram of the modulator was described in detail elsewhere [16]. It was complemented by a B5 47 power source, whereby the modulating voltage amplitude across a 50 Ω load could be controlled within 0-300 V. The time varia tion of voltage U GD (t) at the input to the microwave unit of the GDO [16] (hereinafter this voltage is taken to be roughly equal to the GD voltage) is measured by a circuit consisting of RK50 3 11 and RG 58 cables and two attenuators (RADIALL and R41620000) connected to them.…”

“…This noise arises when a micro wave signal having penetrated through a low pass filter serving for microwave decoupling between the modu lator and resonance chamber falls into the triggering circuit of the oscilloscope [16]. Narrowing the trigger ing circuit operating bandwidth to 1 GHz made it pos sible to adequately solve this problem.…”