Oscillator Current Generator With Switchable TCR Resistors

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Solution Overview

Problem

Current Beta-Multiplier Reference (BMR) circuits in oscillators cannot adjust the frequency characteristic according to temperature changes due to a fixed rate of current change, which is not adaptable to varying temperature conditions.

Innovation Solution

A current generating circuit with a BMR circuit that includes switches and resistors with different temperature coefficients of resistance (TCRs), allowing the rate of current change to be adjusted based on temperature changes, thereby revising the frequency characteristic of the oscillator.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a fixed-rate current generator is used in the oscillator, then the circuit structure is simple, but the frequency characteristic cannot be adjusted according to temperature changes

Engineering Contradiction:

Improvefrequency characteristic adjustment capabilityVSAvoidcircuit structure complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent implements dynamic adjustability by introducing multiple resistors with different TCR values and switches that can selectively connect these resistors to the current generator. This allows the circuit to dynamically change its resistance characteristics based on temperature conditions, enabling frequency characteristic adjustment while maintaining a modular structure that balances complexity and functionality.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the resistance parameter by providing multiple resistors with different temperature coefficients of resistance (TCR). By selectively connecting resistors with appropriate TCR values to the current generator, the circuit can adjust its current change rate according to temperature variations, thereby achieving frequency characteristic adjustment without fundamentally redesigning the entire oscillator structure.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If multiple resistors with different TCRs are added to adjust current change rate, then frequency characteristic adjustment is enabled, but device complexity increases

Engineering Contradiction:

Improvefrequency characteristic accuracyVSAvoidnumber of components

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent segments the resistance adjustment function into multiple discrete resistors with different TCR values, each connected through individual switches. This segmentation allows precise selection of appropriate resistance characteristics for specific temperature ranges, improving frequency characteristic accuracy. The modular segmented structure enables fine-tuned adjustment while keeping each individual component simple and manageable.

Inventive Principle:

Principle #1Segmentation

3Reliability

If the BMR circuit is used to generate reference current, then stable current output is achieved, but the current change rate according to temperature is fixed and cannot be adjusted

Engineering Contradiction:

Improvecurrent stabilityVSAvoidtemperature adaptability

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent introduces resistors with different TCR values as intermediary elements between the stable BMR current generator and the oscillator. These resistors act as mediators that translate the stable reference current into temperature-adaptive current variations. By selectively connecting appropriate resistors, the system maintains the reliability of the BMR circuit while achieving temperature adaptability in the overall oscillator performance.

Inventive Principle:

Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables the adjustment of the frequency characteristic of the oscillator according to temperature changes by varying the rate of current change, aligning the frequency characteristic with desired test results and improving the accuracy of temperature-frequency graphs.

Implementation Method 1

a rate of current change according to a temperature change of the current generator is adjusted based on a temperature coefficient of resistance (TCR) of resistors connected to the one switch, according to adjustment of the one switch

Methodology Applied

Scientific EffectTemperature coefficient of resistance (TCR): Thermal Expansion

Data Source

PatentUS11747850B2Current generating circuit and oscillator using current generating circuit

Publication Date: 2023.09.05 MAGNACHIP SEMICON LTD

AI summary

A current generating circuit includes a current generator configured to supply a reference current, switches connected to the current generator, wherein one switch of the switches is selected and configured to operate, according to a switch selection signal, and one or more resistors, respectively connected to the switches, wherein a rate of current change according to a temperature change of the current generator is adjusted based on a temperature coefficient of resistance (TCR) of resistors connected to the one switch, according to adjustment of the one switch.