Differential Operational Amplifier Temperature Compensation

Solution Overview

Problem

Differential operational amplifiers in bandgap reference voltage generating circuits experience reduced amplifier gain due to temperature variations, leading to unstable reference voltage generation, as the voltage difference between the source and drain terminals of transistors changes with temperature, affecting the PMOSFET and NMOSFET operation.

Innovation Solution

A differential operational amplifier with a voltage adjusting module and a differential signal computing module that adjusts input voltages corresponding to temperature changes, using a current mirror, voltage generating module, and reference voltage resistance device to stabilize the reference voltage by minimizing the voltage difference across transistors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the differential operational amplifier operates at a lower operational voltage, then power consumption is reduced, but the voltage difference VDS between source and drain terminals is suppressed causing the transistor to operate in linear region and amplifier gain decreases

Engineering Contradiction:

Improvepower consumptionVSAvoidamplifier gain

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent introduces a temperature-dependent voltage adjustment mechanism that dynamically compensates for the suppression of VDS at low temperatures. By adding a compensation voltage that increases as temperature decreases, the system maintains adequate VDS headroom for the input transistors to operate in saturation region, preserving amplifier gain while allowing low-voltage operation.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the voltage parameter by introducing a temperature-dependent compensation voltage that modifies the effective VDS across the input transistors. This parameter change ensures that even when the main supply voltage is low, the compensated VDS remains sufficient for proper transistor operation, resolving the contradiction between low voltage operation and maintained gain.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the VGS is increased to maintain constant output currents, then the transistor can operate properly, but the difference between the first voltage and the second voltage changes affecting the reference voltage stability

Engineering Contradiction:

Improvetransistor operation stabilityVSAvoidreference voltage stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent implements a feedback mechanism where the temperature-dependent voltage adjustment is based on detected temperature conditions. The system senses temperature changes and automatically adjusts the compensation voltage to maintain proper VDS, which indirectly stabilizes VGS and prevents excessive changes in the differential input voltage, thereby maintaining reference voltage stability.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent introduces a compensation voltage as an intermediary element that mediates between the low supply voltage conditions and the transistor's voltage requirements. This intermediary compensation voltage absorbs the temperature-dependent variations, preventing them from directly affecting the differential input voltage and reference voltage stability.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Temperature

If the differential operational amplifier operates at a high temperature, then the NMOSFET can operate properly, but the voltage difference VDS is suppressed causing the transistor to operate in linear region and amplifier gain decreases

Engineering Contradiction:

Improveoperational temperature rangeVSAvoidamplifier gain

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The patent introduces a temperature-dependent voltage adjustment mechanism that dynamically compensates for the suppression of VDS at low temperatures. By adding a compensation voltage that increases as temperature decreases, the system maintains adequate VDS headroom for the input transistors to operate in saturation region, preserving amplifier gain while allowing low-voltage operation.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the voltage parameter by introducing a temperature-dependent compensation voltage that modifies the effective VDS across the input transistors. This parameter change ensures that even when the main supply voltage is low, the compensated VDS remains sufficient for proper transistor operation, resolving the contradiction between low voltage operation and maintained gain.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS9535444B2Differential operational amplifier and bandgap reference voltage generating circuit

Publication Date: 2017.01.03 SILICON MOTION INC

AI summary

A differential operational amplifier, which comprises: a voltage adjusting module, coupled between a first predetermined voltage source and a second predetermined voltage source, for adjusting a first voltage via a first voltage adjusting value to generate a first adjusted voltage, and for adjusting a second voltage via a second voltage adjusting value to generate a second adjusted voltage, wherein the first voltage adjusting value and the second voltage adjusting value change corresponding to a temperature; and a differential signal computing module, coupled between the first predetermined voltage source and the second predetermined voltage source, for generating an output voltage according the first adjusted voltage and the second adjusted voltage.