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. 03, 1985
Filed:
Dec. 08, 1982
John P Hill, Broomfield, CO (US);
James J Touchton, Boulder, CO (US);
Storage Technology Corporation, Louisville, CO (US);
Abstract
A low offset position demodulator that may be used in the positioning servo of a disk drive or similar device. A first stage of the demodulator circuit multiplies or switches a servo carrier signal, modulated with position information, with a synchronized gate signal. This first stage of the demodulator circuit includes a differential output and means for controlling the common mode operating point thereof with an external control voltage. A low pass filter, also having a differential output, is coupled to the differential output of the first stage of the demodulator. A differential-to-single-ended conversion stage is tied to the low pass filter output to provide a single position output signal. Also coupled to the low pass filter differential output is an averaging network that averages the signal appearing on one of the two differential signal lines with the signal appearing on the other differential signal line. The resulting averaged signal is compared to a zero voltage reference signal and the difference between these two signals is then used to derive the control voltage applied to the first stage of the modulator. Hence, the common mode operating point of the balanced demodulator is forced to assume and maintain a zero volt level.