NOVEL LOW-COST, LOW-POWER MODULATOR DEMODULATOR USING A SINGLE GAAS FIELD-EFFECT TRANSISTOR/

A novel type of transponder circuit for localisation and identificatio n purposes is presented. The complete circuit contains only one semico nductor device, a 'cold' field effect transistor, which performs both the modulator and the demodulator functions. This makes possible the r ealisation of a low-cost, low-power, high-performance 10GHz transponde r in miniature format. The design of the circuit makes use of simple a nd reliable methods for the modulator function. The demodulator is a F ET detector, which exploits the nonlinear channel resistance of the tr ansistor instead of the Schottky barrier. A theory of this type of det ector is given.