Browse Prior Art Database

Data Detection Circuit

IP.com Disclosure Number: IPCOM000087788D
Original Publication Date: 1977-Mar-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Allen, JW: AUTHOR [+2]

Abstract

A data detection circuit which rectifies, clips and differentiates differential input signals from a readback magnetic transducer is shown in Fig. 1.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 59% of the total text.

Page 1 of 2

Data Detection Circuit

A data detection circuit which rectifies, clips and differentiates differential input signals from a readback magnetic transducer is shown in Fig. 1.

The input signal to terminal 1 is shown in Fig. 2A, its inverse being applied to terminal 2. Also shown is a clip level voltage applied to terminal 3 to give noise rejection. Whichever of transistors Q1, Q2 and Q3 has the highest input voltage will conduct, so that a full-wave rectified and clipped input signal (Fig. 2B) is produced at the base of buffer transistor Q4.

Transistors Q4, Q5, Q6 and Q7, together with capacitor C and resistor R1, form a differentiating network. Transistors Q6 and Q7 are constant current sinks slaved to reference current sink Q8. The input to Q5 is any convenient reference voltage such as ground. As the emitter voltage of Q4 increases, a current I (Fig. 2C) flows in the network C and R1, adding to the collector current of Q4 and subtracting from the collector current of Q5. As the emitter voltage of Q4 decreases, the current in network C and R1 reverses, decreasing Q4's collector current and increasing Q5's collector current. In this way, the current to each sink Q6 and Q7 is kept constant, and the current 1 represents the derivative of the input voltage to Q4. Zero crossings of the derivative correspond to input signal peak positions.

R2 and R3 convert the collector currents of Q4 and Q5 to a differential voltage, having the same waveform as current 1, which is pro...