Novel low-cost, low-power modulator/demodulator using a single GaAs field effect transistor

A novel type of transponder circuit for localisation and identification purposes is presented. The complete circuit contains only one semiconductor device, a `cold´ field effect transistor, which performs both the modulator and the demodulator functions. This makes possible the realisation of a low-cost, low-power, high-performance 10 GHz transponder in miniature format. The design of the circuit makes use of simple and reliable methods for the modulator function. The demodulator is a FET detector, which exploits the nonlinear channel resistance of the transistor instead of the Schottky barrier. A theory of this type of detector is given