The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 16, 1992
Filed:
May. 02, 1991
Michael W Nootbaar, Benicia, CA (US);
Gerald R Newell, Alamo, CA (US);
New SD, Inc., San Francisco, CA (US);
Abstract
A differential capacitive pickoff detector circuit for measuring the difference in spacing of a pair of differential pickoff capacitor plates. Current sources are provided for each output terminal of each of the pair of differential capacitors so that for each capacitor output terminal a current signal alternates between a first current level and a second current level at a predetermined carrier clock switching rate. The capacitors are varied to provide DSB-LC voltage signals across each of the capacitors. The average value of each of the alternating voltages and their amplitudes are automatically adjusted to predetermined levels. The two DSB-LC voltage signals are combined to provide a DSB-SC signal. The DSB-SC signal is synchronously demodulated using a quadrature reference carrier clock signal to provide an output baseband signal which represents the difference between the spacing of the first and second differential capacitor plates.