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:
Mar. 31, 1998
Filed:
Oct. 11, 1996
Petre Popescu, Kanata, CA;
Northern Telecom Limited, Montreal, CA;
Abstract
An RC circuit with voltage controlled delay is provided. The circuit comprises a matched pair of RC delay elements, driven by outputs of a pair of amplifiers comprising a fixed gain amplifier and a variable gain amplifier having gain m so that the delay is dependent on a gain control voltage. Preferably, the circuit is operable in a regime wherein the gain m is linearly dependent on an input control voltage so that the circuit delay is also linearly dependent on the input control voltage. Advantageously, where the amplifier gain has non-linear dependence on a gain control voltage, a control voltage generator comprising a linear to logarithmic converter is used to provide an effective linear operation in response to an input control voltage. The circuit is preferably operated in differential mode, with RC circuit elements implemented simply as resistors and capacitors, and the amplifier and active elements provided by bipolar transistors. Alternatively, MOS devices may be used for R, C elements and active devices. Although differential operation is preferred, single ended operation is an option if one of the pair of input signals is a reference voltage.