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Integrating Peak Detector

IP.com Disclosure Number: IPCOM000037622D
Original Publication Date: 1989-Apr-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Hanson, CC: AUTHOR [+2]

Abstract

Simple servo systems such as a wedge servo or a reference track scheme use a very basic demodulation scheme where the "A" pulses and "B" pulses are integrated over separate periods and then compared in some mathematical manner to generate a position error signal.

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Integrating Peak Detector

Simple servo systems such as a wedge servo or a reference track scheme use a very basic demodulation scheme where the "A" pulses and "B" pulses are integrated over separate periods and then compared in some mathematical manner to generate a position error signal.

The integrating peak detector is the method used to generate a D.C. voltage proportional to the peak of the A.C. signal in either the "A" field or the "B" field.

The circuit shown in Fig. 1 is used to integrate multiple cycles of an A.C. sine wave signal applied to input A and to produce a D.C. output at B which is proportional to the peak amplitude of A.C. input. This D.C. output can be then applied to a number of sample-and-hold circuits for amplitude comparison in an analog manner or directly converted to digital form and stored for later comparison digitally in a microprocessor. The difference between, the ratio of, or some other comparison between the signals, can be used to represent a servo position error if the two A.C. signals are seen at different rotational positions in a magnetic disk drive.

Diode D1 will allow capacitor CI to charge positive toward +12 volts as long as the voltage at the negative side of D2 is greater than the voltage on the capacitor. When the capacitor has charged to the peak of the A.C. signal for the "A" pulses, the capacitor will not charge further (the period of the input signal must be much less than the time constant R.C.). Once the signal h...