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A Low Voltage Bandgap Reference

IP.com Disclosure Number: IPCOM000077217D
Publication Date: 2005-Feb-25
Document File: 2 page(s) / 22K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for a new topology that improves the output impedance issues associated with current summing topology bandgap circuits, but does not require additional supply voltage.

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A Low Voltage Bandgap Reference

Disclosed is a method for a new topology that improves the output impedance issues associated with current summing topology bandgap circuits, but does not require additional supply voltage.

Background

A stable voltage reference is one of the basic blocks for analog circuits, because it is needed in many integrated circuit applications. The most common type is bandgap reference provides a supply and temperature-independent voltage of around 1.26V. The typical bandgap circuit requires a fairly high supply voltage to operate. The current summing topology bandgap circuit generates a fractional bandgap voltage; however, while this circuit achieves low voltage operation, its performance is limited by the transistor output impedance. In the deep, submicron CMOS process where low voltage bandgap reference is most needed, the transistors have an even lower output impedance, and the issue becomes more serious.

General Description

The disclosed method addresses current output impedance issues without requiring extra supply voltage. Figure 1 shows the basic version of a low voltage bandgap, with transistors M0, M1, M2, diodes D0, D1, resistors R0-5 and opamp Amp1. Since the drain voltage of M2 is different from M0 and M1, its current and output voltage are modulated by the drain voltage because of the finite output impedance of M2. Cascoding M0, M1, and M2 increases the impedance, but the cascode transistors connected to M0 and M1 require an additional su...