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Parallel Bandgap Regulator

IP.com Disclosure Number: IPCOM000088870D
Original Publication Date: 1977-Aug-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Azzis, D: AUTHOR

Abstract

The drawing shows an integrated circuit regulator comprising only easily integrable components, namely transistors and resistors, wherein the geometry and current-matching properties, achieved by integrated circuit technology, are used.

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Parallel Bandgap Regulator

The drawing shows an integrated circuit regulator comprising only easily integrable components, namely transistors and resistors, wherein the geometry and current-matching properties, achieved by integrated circuit technology, are used.

The supply voltage to be regulated is applied on terminal 1 to external resistor RS, and regulated voltage VOUT is generated on terminal 2. The regulator comprises two current-source transistors T1 and T2, providing currents i1 and i2. Transistors T1 and T2 are biased through transistors T3 and 4 and resistors R3 and R4.

Currents i1 and i2 are provided to bandgap cells comprising transistors T5 to T8, wherein transistors T6, T7 and T8 have matched emitter resistors R6, R7 and R8 of value r. Common node A of resistors R6, R7 and R8 is connected to the emitter of transistor T5 and to ground through resistor R5 of value 3r.

A voltage divider comprising resistors R9 and R10 is connected across terminal 2 and ground. Voltage VREF at terminal 3 is equal to VOUT.R10/(R10 + R9). Since voltage VREF should be equal to the bandgap voltage, a variation in VOUT, which makes VREF different from this bandgap voltage, causes an unbalance in currents i1 and i2. The output feedback amplifier, comprising transistors T11, T12 and T13, compensates the unbalance to cancel the VOUT variation.

The arrangement of transistors T9 and T10 provides the current-limiting function, protecting the regulator against a short circuit.

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