Reference Voltage Circuit with Segmented Resistive Branches

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Solution Overview

Problem

Existing bandgap reference voltage circuits face challenges in adjusting output voltage while maintaining desired temperature characteristics, and struggle to produce voltages equal to or lower than the forward voltage of bipolar transistors.

Innovation Solution

A reference voltage circuit is designed with a reference current generating circuit that converts the difference between forward voltages of PN junction elements into current, and a voltage generating circuit using resistive elements to produce voltages with positive and negative temperature characteristics, allowing for arbitrary output voltage adjustments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If resistor 608 is adjusted for adjusting the value of the output voltage, then the output voltage value is improved, but the temperature characteristics of the output voltage deteriorate

Engineering Contradiction:

Improveoutput voltage valueVSAvoidtemperature characteristics

Core Design Contradiction:

Measurement precisionVSTemperature

Solution Approach 1:

The voltage generating circuit is divided into two separate branches: a first branch with a first resistive element generating a first voltage with positive temperature characteristics, and a second branch with a second resistive element generating a second voltage with negative temperature characteristics. This segmentation allows independent adjustment of each branch's resistance values to achieve both desired output voltage value and temperature characteristics simultaneously.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention changes the parameters of the resistive elements by providing multiple resistive elements with different resistance values in parallel configurations. By selecting and combining resistive elements with specific resistance values, the circuit can generate voltages with both positive and negative temperature characteristics, enabling independent control of output voltage value and temperature characteristics.

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If the circuit uses bipolar transistor PN junction, then the reference voltage generation is simplified, but the output voltage cannot be equal to or lower than the forward voltage of the PN junction

Engineering Contradiction:

Improvecircuit structureVSAvoidoutput voltage range

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

Instead of using the conventional approach where the bipolar transistor PN junction forward voltage serves as the reference voltage (which limits output to values above the forward voltage), the invention inverts the approach by using resistive elements to generate reference voltages. This allows the output voltage to be any value determined by the resistive element combinations, enabling output voltages equal to or lower than traditional PN junction forward voltages.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The voltage generating circuit with parallel resistive elements serves multiple functions: it can generate voltages with positive temperature characteristics, negative temperature characteristics, or compensated temperature characteristics depending on the configuration. This multi-functionality allows the same circuit structure to produce a wide range of output voltages with different temperature characteristics, greatly expanding the adaptability and versatility of the reference voltage circuit.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 generation of arbitrary output voltages with arbitrary temperature characteristics, improving the flexibility and accuracy of the reference voltage circuit.

Implementation Method 1

the first resistive element being configured to generate a first voltage having positive temperature characteristics when the first current flows through the first resistive element

Methodology Applied

Scientific EffectPositive temperature characteristics:

Implementation Method 2

the second resistive element being configured to generate a second voltage having negative temperature characteristics when the first current and the second current flow through the second resistive element

Methodology Applied

Scientific EffectNegative temperature characteristics:

Data Source

PatentUS9910452B2Reference-voltage circuit

Publication Date: 2018.03.06 ABLIC INC

AI summary

Provided is a reference voltage circuit capable of adjusting an arbitrary output voltage to have arbitrary temperature characteristics. The reference voltage circuit includes: a reference current generating circuit configured to convert a difference between forward voltages of a plurality of PN junction elements into current to generate a first current; a current generating circuit configured to use the first current generated by the reference current generating circuit to generate a second current; and a voltage generating circuit including a first resistive element and a second resistive element, the first resistive element being configured to generate a first voltage having positive temperature characteristics when the first current flows through the first resistive element, the second resistive element being configured to generate a second voltage having negative temperature characteristics when the first current and the second current flow through the second resistive element. The reference voltage circuit outputs a reference voltage obtained by adding the first voltage to the second voltage.