Large-signal performance of microwave transit-time devices in mixed tunneling and avalanche breakdown

A large-signal model for Read-type diode structures with narrow generation-region widths where mixed tunneling and avalanche exist is given. The generation region is modeled by use of a modified Read equation along with effective ionization rates. The injected current pulse, which is formed in the generation region, is calculated in isolation from the drift region in order that the effects of tunneling current can be clearly shown. The drift region is modeled by use of difference-equation versions of the device equations and is suitably interfaced to the generation region. The large-signal model of the total device is used to calculate the device admittance and efficiency. Large-signal results for GaAs and Si devices are given and the results are discussed and compared.