US6647764B1
Expired / Lapsed
US
⏱️ 0.0 years remaining
Quartz crystal microbalance with feedback loop for automatic gain control
Assignee: Alere Switzerland GmbH
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Filing: 1999-10-21
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Granted: 2003-11-18
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Expires: 2019-10-21
Abstract
Abstract An analytical apparatus, such as a quartz crystal microbalance, comprising a piezoelectric sensor and an oscillator circuit, coupled to the sensor, to oscillate at a frequency substantially determined by a resonant frequency of the sensor, and to provide an output signal at the oscillator frequency at an output, the oscillator circuit incorporates means to maintain a substantially constant drive signal to the piezoelectric sensor. Preferably the substantially constant drive signal is maintained by AGC means (33) within a feedback loop of the oscillator. Advantageously the gain control signal is used as an indication of the Q of the piezoelectric sensor. It is desirable that the drive signal to the sensor is substantially sinusoidal since this provides greater accuracy, sensitivity and stability for the apparatus. This can be achieved by ensuring that all the elements in the feedback loop providing signal gain and attenuation are configured to operate in a substantially linear mode.
Inventors
- 👤 Frank Paul
- 👤 Karl Pavey
- 👤 Richard C Payne
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 18:04
CPC Classifications
G; G01; G01N; G01N29/00; G01N29/02; G01N29/036; G01G; G01G3/00; G01G3/12; G01G3/13; G01N2291/00; G01N2291/02; G01N2291/025; G01N2291/0256
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
113 words
Analytical apparatus comprising a piezoelectric sensor; and an oscillator circuit, coupled to the sensor to oscillate at a frequency substantially determined by a resonant frequency of the sensor, and to provide an output signal at the oscillator frequency at an output, wherein the oscillator circuit incorporates means to maintain a substantially constant drive signal to the piezoelectric sensor, wherein the oscillator circuit includes an amplifier with feedback coupling the output to an input of the amplifier to form a feedback loop through the amplifier, wherein the feedback loop incorporates automatic gain control (AGC) means, and wherein the AGC means comprises rectification means, integrator means, and variable gain means responsive to the integrator means.
Claim 2
Dependent Claim
113 words
Analytical apparatus comprising a piezoelectric sensor; and an oscillator circuit, coupled to the sensor to oscillate at a frequency substantially determined by a resonant frequency of the sensor, and to provide an output signal at the oscillator frequency at an output, wherein the oscillator circuit incorporates means to maintain a substantially constant drive signal to the piezoelectric sensor, wherein the oscillator circuit includes an amplifier with feedback coupling the output to an input of the amplifier to form a feedback loop through the amplifier, wherein the feedback loop incorporates automatic gain control (AGC) means, and wherein the AGC means comprises rectification means, integrator means, and variable gain means responsive to the integrator means.
Claim 3
Dependent Claim
26 words
Apparatus as claimed in claim 1 further comprising a second output to provide an output signal corresponding to a gain control signal of the AGC means.
Claim 4
Dependent Claim
13 words
Apparatus as claimed in claim 1 wherein the drive signal is substantially sinusoidal.
Claim 5
Dependent Claim
50 words
Apparatus as claimed in claim 3 wherein the oscillator circuit includes an amplifier with feedback coupling the output to an input of the amplifier to form a feedback loop, and all elements in the feedback loop providing signal gain and attenuation are configured to operate in a substantially linear mode.
Claim 6
Dependent Claim
14 words
Apparatus as claimed in claim 1 wherein the piezoelectric sensor comprises a quartz crystal.
Claim 7
Dependent Claim
36 words
Apparatus as claimed in claim 1 wherein a structure or compound which interacts with a material of chemical or biological origin is attached to a surface of the crystal or to an electrode on the crystal.
Claim 8
Dependent Claim
72 words
Analytical apparatus comprising a piezoelectric sensor; and an oscillator circuit, coupled to the sensor to oscillate at a frequency substantially determined by a resonant frequency of the sensor, and to provide an output signal at the oscillator frequency at an output, wherein the oscillator circuit incorporates means to maintain a substantially constant drive signal to the piezoelectric sensor, and wherein the piezoelectric sensor has two terminals, both of which are actively driven.
Claim 9
Dependent Claim
72 words
Analytical apparatus comprising a piezoelectric sensor; and an oscillator circuit, coupled to the sensor to oscillate at a frequency substantially determined by a resonant frequency of the sensor, and to provide an output signal at the oscillator frequency at an output, wherein the oscillator circuit incorporates means to maintain a substantially constant drive signal to the piezoelectric sensor, and wherein the piezoelectric sensor has two terminals, both of which are actively driven.
Claim 10
Dependent Claim
107 words
Analytical apparatus comprising a piezoelectric sensor; and an oscillator circuit, coupled to the sensor to oscillate at a frequency substantially determined by a resonant frequency of the sensor, and to provide an output signal at the oscillator frequency at an output, wherein the oscillator circuit incorporates means to maintain a substantially constant drive signal to the piezoelectric sensor, wherein the oscillator circuit includes an amplifier with feedback coupling the output to an input of the amplifier to form a feedback loop through the amplifier, wherein the feedback loop incorporates automatic gain control (AGC) means, and wherein the oscillator circuit incorporates a second feedback loop comprising filter means.
Claim 11
Dependent Claim
107 words
Analytical apparatus comprising a piezoelectric sensor; and an oscillator circuit, coupled to the sensor to oscillate at a frequency substantially determined by a resonant frequency of the sensor, and to provide an output signal at the oscillator frequency at an output, wherein the oscillator circuit incorporates means to maintain a substantially constant drive signal to the piezoelectric sensor, wherein the oscillator circuit includes an amplifier with feedback coupling the output to an input of the amplifier to form a feedback loop through the amplifier, wherein the feedback loop incorporates automatic gain control (AGC) means, and wherein the oscillator circuit incorporates a second feedback loop comprising filter means.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2006-11-17 | 2007-05-19 | 2007-11-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2010-11-17 | 2011-05-19 | 2011-11-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2014-11-17 | 2015-05-19 | 2015-11-18 | $7700.00 | Window Closed / Lapsed |