Browse Prior Art Database

+V Noise Limiter

IP.com Disclosure Number: IPCOM000041329D
Original Publication Date: 1984-Jan-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Pollmann, K: AUTHOR [+4]

Abstract

When several driver stages are simultaneously switched, a noise voltage pulse occurs at the parasitic inductance Lp of the supply voltage line which connects the positive pole +V of the operating voltage source, through a circuit board, to the driver stages integrated on a semiconductor chip. The circuit diagram of a push-pull driver stage, consisting of the NPN transistors T1, T2, T3 and the resistors R1, R2, is shown in the figure on the left of the broken line. For reducing or limiting the noise voltage pulse, which is proportional to the time derivative of current I, PNP transistor T4 and NPN transistor T5 as well as resistor R3 are provided.

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+V Noise Limiter

When several driver stages are simultaneously switched, a noise voltage pulse occurs at the parasitic inductance Lp of the supply voltage line which connects the positive pole +V of the operating voltage source, through a circuit board, to the driver stages integrated on a semiconductor chip. The circuit diagram of a push-pull driver stage, consisting of the NPN transistors T1, T2, T3 and the resistors R1, R2, is shown in the figure on the left of the broken line. For reducing or limiting the noise voltage pulse, which is proportional to the time derivative of current I, PNP transistor T4 and NPN transistor T5 as well as resistor R3 are provided. If the voltage drop at the parasitic inductance Lp of line 1 exceeds a particular value when several transistors T2, connected in parallel to the supply voltage, are simultaneously switched on, transistor T4 and thus transistor T5 become conductive. When T5 is conductive, it draws part of the base current from transistor T2, so that the current through T2 rises less rapidly, leading to a reduced noise voltage at the inductance Lp of the supply voltage line.

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