A resonant gate silicon bandpass transistor

The use of a suspended clamped-free cantilever beam as the gate electrode for an MOS-type silicon transistor results in a minute, very high Q bandpass filter for integrated circuits. The center frequency of this filter is equal to the mechanical resonant frequency of the cantilever beam electrode. In operation, the metal cantilever is electrically polarized. Input signals are applied between the cantilever and an additional insulated input gate located underneath a portion of the cantilever away from the source-drain regions of the transistor. Electrostatic forces, exerted on the cantilever by the input signal, cause a relatively large cantilever motion perpendicular to the silicon surface at mechanical resonance, with subsequent field-effect modulation of the channel conductance and a corresponding A.C. output voltage. Input frequencies off resonance are rejected.