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Noise Cancellation Between Driver Sensing Line Conductors

IP.com Disclosure Number: IPCOM000084548D
Original Publication Date: 1975-Nov-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Brennan, PE: AUTHOR [+2]

Abstract

Driver-sensing arrangements are commonly found in electronic equipment. Often a large drive signal will be coupled into a sensing conductor which is geared to pick up very low level sense signals. Differential schemes are generally used both for the sense and driver lines. This description pertains to the connection between two units which perform the function of transmitting these signals. Specific examples are: 1) Wires on integrated circuit chips. 2) Connections to a memory array. 3) The application considered here which is for a disk file system, using a flexible cable to connect the head arrangement to the remaining circuitry.

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Noise Cancellation Between Driver Sensing Line Conductors

Driver-sensing arrangements are commonly found in electronic equipment. Often a large drive signal will be coupled into a sensing conductor which is geared to pick up very low level sense signals. Differential schemes are generally used both for the sense and driver lines. This description pertains to the connection between two units which perform the function of transmitting these signals. Specific examples are: 1) Wires on integrated circuit chips. 2) Connections to a memory array. 3) The application considered here which is for a disk file system, using a flexible cable to connect the head arrangement to the remaining circuitry.

Fig. 1 shows a typical driver-sensing connection, while Fig. 2 schematically shows the capacitive coupling between the various connecting wires.

In Fig. 2 a differential signal is induced between lines 1 and 2 which is then coupled differentially to lines 3 and 4. A compensation method is proposed which will reduce this coupling to zero by using a new design program for obtaining accurate capacitance computations [1]. This compensation is provided by the ground lines (see Fig. 3) which are designed in such a way that the coupling capacitances C13, C14, C23 and C24 are made exactly the same. As a result, the signal coupled into lines 3 and 4 from lines 1 and 2 will exactly cancel.

Without the ground conductors G1, G2 and G3, the coupled capacitance C23 is always greater than C14....