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IMPROVED REGULATOR FOR ALTERNATOR WHINE SUPPRESSION

IP.com Disclosure Number: IPCOM000006818D
Original Publication Date: 1993-Mar-01
Included in the Prior Art Database: 2002-Feb-05
Document File: 3 page(s) / 93K

Publishing Venue

Motorola

Related People

Klaus Dirksmeier: AUTHOR

Abstract

If an interference voltage is modulated onto the sup- ply voltage of a transceiver unit, all parameters specified in the relevant guidelines must be complied with. One parameter that is particularly affected is the signal/noise ratio of the transmitter (e.g. Staccato TX SIN < 40 dB). This interference is frequently eliminated by means of an expensive filter in the supply voltage. The solution demonstrated here does not require such a fdter.

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INC. Technical Developments Volume 18 March 1993

IMPROVED REGULATOR FOR ALTERNATOR WHINE SUPPRESSION

by Klaus Dirksmeier

DESCRIPTION OF ALTERNATOR

WHINE IMPROVEMENT ClRCUlT

  If an interference voltage is modulated onto the sup- ply voltage of a transceiver unit, all parameters specified in the relevant guidelines must be complied with. One parameter that is particularly affected is the signal/noise ratio of the transmitter (e.g. Staccato TX SIN < 40 dB). This interference is frequently eliminated by means of an expensive filter in the supply voltage. The solution demonstrated here does not require such a fdter.

ORIGIN OF SPURIOUS DEVIATION

  The RF in the output stage is amplitude-modulated by the interference on the supply voltage. Due to its small regulation time constants, the power regulator continuously attempts to correct this power fluctuation via the control voltage. The control voltage is also mod- ulated by the disturbed supply voltage. This effect pro- duces an impedance change in the PWR driver stage, which reacts upon the VCO and results in residual FM. (See block diagram).

IMPROVEMENT TO REGULATOR CIRCUIT

  A small regulator time constant is not required as the output stage load variations seldom exceed 100 Hz in practice. The negative feedback of the circuit is increased by the network comprising resistor R460: 470 n and capacitor C454: 100 nF (see circuit diagram: TX PWR CONTROL). The time constant of the PI regulator is increased, so that th...