A proposed punch-through microwave negative-resistance diode

A new microwave negative-resistance diode is proposed. The diode is similar to the Read diode insofar as the negative resistance is partially due to the finite transit time of carriers flowing through a depletion region. Unlike the Read diode, however, the carriers are injected into the depletion region by punch through rather than by avalanche. The resulting device is therefore expected to have a considerably better noise performance than the Read diode. The paper first explains qualitatively the punch-through operation of the proposed device and contrasts it with similar structures proposed earlier by Read and by Shockley. The large signal admittance of the punch-through diode is then obtained by using a sharp pulse approximation of the injection process. A device Q of -15 is calculated. Considering the device as a microwave oscillator, it is found that conversion efficiencies of the order of 20 percent should be possible. Estimates of the upper bounds on the microwave power are given. The paper concludes with a detailed account of design considerations for the device. Numerical designing examples for the frequency range of 1 to 5O GHz are given.