Attenuator and Output Load Circuit for Temperature-Stable PA Gain

Solution Overview

Problem

Gain variations in power amplifier elements due to temperature characteristics lead to performance degradation and increased operating costs, particularly in CMOS or bipolar transistors used in power amplifiers and low noise amplifiers.

Innovation Solution

An attenuator circuit with a first control circuit controlling the ON resistance of FETs to stabilize the gate bias voltage, and an output load circuit with a second control circuit adjusting impedance based on temperature characteristics, using PTAT current sources to compensate for gain variations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the driving current of the power amplifier element is increased to compensate for gain variations caused by temperature characteristics, then the gain stability is improved, but the temperature further increases and the consumption current increases

Engineering Contradiction:

Improvegain stabilityVSAvoidoperating temperature

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The patent changes the resistance values of the first and second resistors based on temperature characteristics. Specifically, the resistors are designed with positive temperature coefficients so that their resistance increases with temperature, which compensates for the gain decrease of the power amplifier element at high temperatures without increasing the driving current

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the harmful effect of temperature increase into a beneficial effect by utilizing the positive temperature coefficient of the resistors. The temperature rise that would normally cause gain degradation is instead used to increase resistor resistance, which compensates for the gain variation and stabilizes the overall amplifier gain

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Reliability

If the driving current of the power amplifier element is increased to compensate for gain variations caused by temperature characteristics, then the gain stability is improved, but the consumption current increases

Engineering Contradiction:

Improvegain stabilityVSAvoidconsumption current

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent changes the resistance values of the first and second resistors based on temperature characteristics. Specifically, the resistors are designed with positive temperature coefficients so that their resistance increases with temperature, which compensates for the gain decrease of the power amplifier element at high temperatures without increasing the driving current

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the harmful effect of temperature increase into a beneficial effect by utilizing the positive temperature coefficient of the resistors. The temperature rise that would normally cause gain degradation is instead used to increase resistor resistance, which compensates for the gain variation and stabilizes the overall amplifier gain

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Reliability

If resistors with positive temperature coefficients are used to compensate for gain variations, then the gain stability across temperature is improved, but the device complexity increases

Engineering Contradiction:

Improvegain stabilityVSAvoidcircuit complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent makes the first and second resistors serve multiple functions: they provide the necessary biasing for the power amplifier element and simultaneously compensate for temperature-induced gain variations through their positive temperature coefficients. This eliminates the need for separate compensation circuits

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the temperature compensation function with the biasing function by using the same resistors for both purposes. The first resistor provides biasing for the power amplifier element while the second resistor provides biasing for the amplifier circuit, and both resistors simultaneously perform temperature compensation

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS20260012150A1Attenuator circuit and output load circuit

Publication Date: 2026.01.08 MURATA MFG CO LTD

AI summary

An attenuator circuit includes an input/output circuit that is provided at a stage preceding an power amplifier circuit, and a first control circuit that controls a gain of the input/output circuit. The input/output circuit includes at least a first resistor that is electrically connected between an input terminal and an output terminal, and a first FET that is electrically connected between the output terminal and a reference potential point. The first control circuit includes at least a second FET that has an ON resistance that is substantially equal to an ON resistance of the first FET at a time when a gate bias voltage that is the same as a gate bias voltage of the first FET is applied. A gate of the first FET and a gate of the second FET are electrically connected.