Voltage Reference Circuit Temperature Compensation

Solution Overview

Problem

Conventional constant transconductance (Gm) voltage reference circuits exhibit strong temperature dependence, leading to significant variations in output voltage over temperature ranges, which is not adequately compensated by existing designs.

Innovation Solution

Incorporating temperature compensation mechanisms, such as using an op amp with adjustable gain and connecting VREF to the gate of an additional NMOS transistor to increase source-gate resistance, which helps stabilize the output voltage across varying temperatures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by stationary object

If constant Gm voltage reference circuit is used, then area and power requirements are reduced, but temperature dependence increases significantly

Engineering Contradiction:

Improvepower requirementVSAvoidtemperature stability

Core Design Contradiction:

Use of energy by stationary objectVSReliability

Solution Approach 1:

The voltage reference circuit is divided into two separate circuits: a constant Gm voltage reference circuit (first circuit) and a temperature compensation circuit (second circuit). The first circuit generates the base reference voltage with low power consumption, while the second circuit generates the temperature compensation voltage. This segmentation allows each circuit to be optimized for its specific function, maintaining the low power advantage while adding temperature stability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

An operational amplifier is introduced as an intermediary element to sum the output voltage from the constant Gm voltage reference circuit and the temperature compensation voltage from the second circuit. The op amp combines these two voltage components to produce the final compensated reference voltage, enabling the integration of temperature compensation without significantly increasing power consumption.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If bandgap voltage reference circuit is used, then temperature stability is improved, but area and power requirements increase

Engineering Contradiction:

Improvetemperature stabilityVSAvoidpower requirement

Core Design Contradiction:

ReliabilityVSUse of energy by stationary object

Solution Approach 1:

The invention changes the approach to temperature compensation by using a constant Gm circuit with adjustable transconductance parameter rather than the traditional bandgap approach. By controlling the transconductance parameter of the constant Gm circuit, the invention achieves temperature compensation with significantly lower power consumption and area requirements compared to bandgap circuits.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If bandgap voltage reference circuit is used, then temperature stability is improved, but area requirements increase

Engineering Contradiction:

Improvetemperature stabilityVSAvoidarea requirement

Core Design Contradiction:

ReliabilityVSUse of energy by stationary object

Solution Approach 1:

The voltage reference circuit is divided into two separate circuits: a constant Gm voltage reference circuit (first circuit) and a temperature compensation circuit (second circuit). The first circuit generates the base reference voltage with low power consumption, while the second circuit generates the temperature compensation voltage. This segmentation allows each circuit to be optimized for its specific function, maintaining the low power advantage while adding temperature stability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention changes the approach to temperature compensation by using a constant Gm circuit with adjustable transconductance parameter rather than the traditional bandgap approach. By controlling the transconductance parameter of the constant Gm circuit, the invention achieves temperature compensation with significantly lower power consumption and area requirements compared to bandgap circuits.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS9442506B2Voltage reference circuit with temperature compensation

Publication Date: 2016.09.13 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A voltage reference circuit with temperature compensation includes a power supply, a first reference voltage supply, a first PMOS transistor, a second PMOS transistor, a first NMOS transistor, a second NMOS transistor, a resistor connected to the second NMOS source and ground. The voltage reference circuit also includes a second reference voltage supply, a third PMOS transistor, a fourth PMOS transistor, a third NMOS transistor, a fourth NMOS transistor, and a fifth NMOS transistor with a drain connected to the source of the fourth NMOS transistor, a source connected to the ground, and a gate connected to the first reference voltage output.