Abstract :
Both avalanche (IMPATT) and GaAs devices have been investigated for electronically tuned oscillators at C-, X-, and Ku-band. Models for each type of device have been formulated, and excellent experimental agreement obtained with the computer simulations as far as output power, bandwidth, and detail of the power-frequency characteristic. This paper will discuss device equivalent circuits for each type of device and present experimental data to both substantiate the model and establish element values. This is the first time that equivalent circuits for these devices have been verified by wide-band electronic tuning. With 6 dB of power loss from the optimum device performance in waveguide circuits, bandwidths of 2 GHz at X-band have been obtained with avalanche devices. Under identical conditions, 5 GHz of bandwidth at X-band have been obtained with bulk GaAs devices. To further establish the frequency characteristics of these devices, identical devices have been operated in X- and Ku-band circuits. Element values for both of the device equivalent circuits have thus been verified from 7 to 18 GHz as a function of doping concentrations and device geometry.
