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Ripple and Noise Simulator for a Power Supply Tester

IP.com Disclosure Number: IPCOM000061501D
Original Publication Date: 1986-Aug-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Landrock, J: AUTHOR [+4]

Abstract

It is desirable to test how the ripple and noise at the input of a regulated power supply influences its output voltage. The figure shows a circuit for generating a ripple and noise voltage URN which is superimposed on the DC input voltage for the power supply to be tested. Thus, the circuit described in this article replaces the usual rectifier and bulk capacitor at the input of a power supply. An auxiliary power supply APS delivers a bulk voltage UBULK to a series-connected field-effect transistor. The negative terminal of APS is connected to the power supply ground, whereas its positive terminal is connected to a separate APS ground.

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Ripple and Noise Simulator for a Power Supply Tester

It is desirable to test how the ripple and noise at the input of a regulated power supply influences its output voltage. The figure shows a circuit for generating a ripple and noise voltage URN which is superimposed on the DC input voltage for the power supply to be tested. Thus, the circuit described in this article replaces the usual rectifier and bulk capacitor at the input of a power supply. An auxiliary power supply APS delivers a bulk voltage UBULK to a series-connected field- effect transistor. The negative terminal of APS is connected to the power supply ground, whereas its positive terminal is connected to a separate APS ground. The voltage drop UDS across the drain and source of this FET can be adjusted by means of an operational amplifier OP, to the non-inverting input of which a reference potential UP2 is applied by a potentiometer P1. Voltage drop UDS can be modulated by URN which is applied by means of a second potentiometer P2 and a blocking capacitor C1 to the non-inverting input of OP. Thus, the input voltage UIN to the power supply under test PSUT consists of a DC voltage on which a desired ripple and noise voltage has been superimposed, whose influence on PSUT can be detected across load resistor RL . For URN, frequencies of up to several megacycles are possible.

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