High resolution resonant double gate transistor for oscillating structures

We present a resonant double gate transistor (RDGT) that is a refined versi on of the resonant gate transistor (RGT). The important difference between RGTs reported earlier and our new device is that in addition to the oscilla ting gate we also have a fixed "floating" gate. The additional gate provide s long term stability and makes possible the choice of the working point of the transistor independent of the bias applied to the oscillating gate. We use the RDGT in a high resolution displacement sensing technique for vibra ting conductors. According to simulations it provides a spatial resolution of the order of 10(-13) m Hz(-1/2) with an air gap of 2 mum and a dc voltag e of 10 V on the oscillating gate. First measurements on fabricated RDGTs r esulted in a spatial resolution one order of magnitude lower than indicated by simulations, i.e. of the order of 10(-12) m Hz(-1/2). (C) 2001 Elsevier Science B.V. All rights reserved.