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Title: Active shunt capacitance cancelling oscillator circuit

Abstract

An oscillator circuit is disclosed which can be used to produce oscillation using a piezoelectric crystal, with a frequency of oscillation being largely independent of any shunt capacitance associated with the crystal (i.e. due to electrodes on the surfaces of the crystal and due to packaging and wiring for the crystal). The oscillator circuit is based on a tuned gain stage which operates the crystal at a frequency, f, near a series resonance frequency, f.sub.S. The oscillator circuit further includes a compensation circuit that supplies all the ac current flow through the shunt resistance associated with the crystal so that this ac current need not be supplied by the tuned gain stage. The compensation circuit uses a current mirror to provide the ac current flow based on the current flow through a reference capacitor that is equivalent to the shunt capacitance associated with the crystal. The oscillator circuit has applications for driving piezoelectric crystals for sensing of viscous, fluid or solid media by detecting a change in the frequency of oscillation of the crystal and a resonator loss which occur from contact of an exposed surface of the crystal by the viscous, fluid or solid media.

Inventors:
Publication Date:
Research Org.:
Sandia National Lab. (SNL-CA), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1174504
Patent Number(s):
6,624,708
Application Number:
10/183,112
Assignee:
Sandia Corporation (Albuquerque, NM)
DOE Contract Number:  
AC04-94AL85000
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
24 POWER TRANSMISSION AND DISTRIBUTION

Citation Formats

Wessendorf, Kurt O. Active shunt capacitance cancelling oscillator circuit. United States: N. p., 2003. Web.
Wessendorf, Kurt O. Active shunt capacitance cancelling oscillator circuit. United States.
Wessendorf, Kurt O. Tue . "Active shunt capacitance cancelling oscillator circuit". United States. https://www.osti.gov/servlets/purl/1174504.
@article{osti_1174504,
title = {Active shunt capacitance cancelling oscillator circuit},
author = {Wessendorf, Kurt O.},
abstractNote = {An oscillator circuit is disclosed which can be used to produce oscillation using a piezoelectric crystal, with a frequency of oscillation being largely independent of any shunt capacitance associated with the crystal (i.e. due to electrodes on the surfaces of the crystal and due to packaging and wiring for the crystal). The oscillator circuit is based on a tuned gain stage which operates the crystal at a frequency, f, near a series resonance frequency, f.sub.S. The oscillator circuit further includes a compensation circuit that supplies all the ac current flow through the shunt resistance associated with the crystal so that this ac current need not be supplied by the tuned gain stage. The compensation circuit uses a current mirror to provide the ac current flow based on the current flow through a reference capacitor that is equivalent to the shunt capacitance associated with the crystal. The oscillator circuit has applications for driving piezoelectric crystals for sensing of viscous, fluid or solid media by detecting a change in the frequency of oscillation of the crystal and a resonator loss which occur from contact of an exposed surface of the crystal by the viscous, fluid or solid media.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2003},
month = {9}
}

Patent:

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