20 GHz Wavelet Generator Using a Gated Tunnel Diode

We demonstrate the use of a GaAs-AlGaAs gated tunnel diode (GTD) in an ultra-wideband (UWB) wavelet generator. An inductor is integrated to form an oscillator circuit, which is driven by the negative differential conductance property of a GTD. It is demonstrated that as the gate tunes the magnitude of the output conductance, the oscillator may be switched on and off, creating short RF pulses. The shortest pulses generated are 500 ps long, the highest output power for the free running oscillator is $-$4.1 dBm, and the highest oscillation frequency is 22 GHz. Analytical expressions based on the van der Pol equation describing the pulse length and amplitude are presented. This technique is applicable for high frequency impulse radio UWB implementations.