# Digital mixer for quartz crystal thickness monitor

Shivalingappa, L and Srinivasan, MP and Mohan, S (1996) Digital mixer for quartz crystal thickness monitor. In: Vacuum, 47 (1). pp. 87-89.

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## Abstract

A stable digital mixer used in a quartz crystal thickness monitor for monitoring the rate of evaporation and total thickness of films during thin film deposition is reported. The mixer circuit plays a vital role in the crystal monitor. A ‘D’ flip-flop is used as a mixer. The mixer receives inputs both from the reference oscillator and the monitor oscillator and produces an output which is the difference of the two input frequencies. The design aspects of the mixer, its stability and its repeatability are described. The measured stability of the mixer shows a variation of 1.5Hz for 2 h at an ambient temperature of $30^oC (\pm 2^o)$ with a beat frequency of 151KHz. The performance of the mixer has been studied in the beat frequency range 0.5Hz -2.lMHz. The mixer is coupled to the crystal monitor and its performance is studied by evaporating different materials and the results are reported.

Item Type: Journal Article Copyright of this article belongs to Elsevier. Division of Physical & Mathematical Sciences > Instrumentation and Applied Physics (Formally ISU) 02 Feb 2007 19 Sep 2010 04:34 http://eprints.iisc.ernet.in/id/eprint/9648