Cascode Power Amplifier Gain Control for Gentle Burst Ramping

Solution Overview

Problem

Existing power amplification modules face challenges in controlling the gain to match the waveform characteristics defined for burst operations in radio communication systems, leading to steep gain rising and difficulty in adjusting the power output signal effectively, while also requiring a larger chip size when using low drop output regulators.

Innovation Solution

A power amplification module with a cascode-connected first and second transistor configuration, where the first transistor is emitter-grounded and the second transistor is cascode-connected, utilizing a gain control voltage and current generation circuit to adjust the gain, allowing for a smaller module size and gentle gain rising characteristic.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the gain of the power amplification module is controlled by the ramp voltage, then the gain control is simplified, but the slope of the gain change becomes larger making it difficult to match waveform characteristics

Engineering Contradiction:

Improvegain control simplicityVSAvoidgain rising characteristic control precision

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The power amplification module is divided into multiple stages: a first power amplification stage with a first transistor controlled by ramp voltage, and a second power amplification stage with a second transistor controlled by a current source. This segmentation allows independent control of gain characteristics in different stages, enabling gentle gain rising while maintaining control simplicity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention changes the control parameter from direct voltage control to combined voltage and current control. By controlling the second transistor with a current source whose magnitude is determined by the ramp voltage, the system achieves gentler gain rising characteristics while maintaining ease of operation.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If a low drop output regulator is used to control the gain, then the gain rising characteristic can be adjusted, but the chip size becomes larger

Engineering Contradiction:

Improvegain rising characteristic adjustabilityVSAvoidchip size

Core Design Contradiction:

Manufacturing precisionVSArea of stationary object

Solution Approach 1:

The power amplification module is divided into multiple stages: a first power amplification stage with a first transistor controlled by ramp voltage, and a second power amplification stage with a second transistor controlled by a current source. This segmentation allows independent control of gain characteristics in different stages, enabling gentle gain rising while maintaining waveform characteristic compliance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention changes the control parameter from direct voltage control to combined voltage and current control. By controlling the second transistor with a current source whose magnitude is determined by the ramp voltage, the system achieves gentler gain rising characteristics while maintaining ease of operation.

Inventive Principle:

Principle #35Parameter changes

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

The solution enables a power amplification module with a smaller size that can effectively adjust the gain rising characteristic, improving the ability to control the output signal according to the waveform characteristic, while reducing the slope of the gain change and maintaining a compact design.

Implementation Method 1

a first transistor which is emitter-grounded and in which an input signal and a first bias current are supplied to a base thereof

Methodology Applied

Scientific EffectTransistor amplification:

Implementation Method 2

a second transistor which is cascode-connected to the first transistor and in which the gain control voltage is supplied to a base thereof

Methodology Applied

Scientific EffectCascode configuration:

Data Source

PatentUS9559654B2Power amplification module

Publication Date: 2017.01.31 MURATA MFG CO LTD

AI summary

Disclosed is a power amplification module which has a comparatively small size and is capable of adjusting the rising characteristic of a gain. The power amplification module includes a first gain control current generation circuit which generates a first gain control current changing with a control voltage, a first bias current generation circuit which generates a first bias current according to the first gain control current, a gain control voltage generation circuit which generates a gain control voltage changing with the control voltage, a first transistor which is emitter-grounded and in which an input signal and the first bias current are supplied to a base thereof, and a second transistor which is cascode-connected to the first transistor and in which the gain control voltage is supplied to a base thereof and a first output signal obtained by amplifying the input signal is output from a collector thereof.