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:
Sep. 22, 1992
Filed:
Sep. 14, 1990
Gerald R Newell, Alamo, CA (US);
Pradeep Bhardwaj, Danville, CA (US);
New SD, Inc., San Francisco, CA (US);
Abstract
A voltage-to-frequency converter provides an output signal, the frequency of which is proportional to the instantaneous level of a reference-frequency signal, which is proportional to the output signal of a parameter-sensing circuit. An up-down frequency counter counts the output pulses of the voltage-to-frequency converter. An up-down control terminal coupled to the reference-frequency signal switches the counting direction of the up-down counter to demodulate the output signal of the voltage-to-frequency converter and to provide a digital output signal representative of the time integral of the amplitude of the parameter being sensed. An undersired input signal is reduced by subtracting a cancellation signal having the format of the undesired signal from the undesired input signal. The filter includes a subtractor, or difference circuit, the output of which is coupled to a voltage-to-frequency converter. A feedback path is provided between the output terminal of the voltage-to-frequency converter and one input terminal of the difference circuit. The feedback path includes a circuit for selectively converting the frequency output signal representing the undesired input signal to a cancellation signal. The circuit for selectively converting includes a synchronous carrier signal generator and a reversible up-down counter.