Dual-Amplifier Transmitting Output Stage for Low-Power Efficiency

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Solution Overview

Problem

In modern mobile communications systems, the power amplifiers in transmitting output stages are inefficient at low input power levels due to high idling currents, leading to reduced efficiency and increased data error rates, as they are designed for maximum power levels to ensure sufficient transmission even at long distances from the base station.

Innovation Solution

A transmitting output stage with a first and second controllable amplification device, along with matching networks that adjust impedance based on operating mode, allowing for optimal idling current reduction and improved linearity by matching load impedance at low power levels, enabling efficient operation with either high or low output power levels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the power amplifier is designed for maximum power levels to ensure sufficient transmission at long distances, then the transmitting power is sufficient, but the efficiency decreases at low input power levels due to high idling currents

Engineering Contradiction:

Improvetransmitting powerVSAvoidefficiency at low power levels

Core Design Contradiction:

PowerVSLoss of energy

Solution Approach 1:

The transmitting output stage is divided into two separate amplification devices: a first power amplifier designed for high power levels and a second power amplifier designed for low power levels. Each amplifier is optimized for its specific power range, with the first amplifier having higher idling current capability and the second amplifier having lower idling current for improved efficiency at low power levels.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system dynamically switches between the first and second amplification devices based on the required output power level. A control mechanism monitors the operating conditions and activates the appropriate amplifier, enabling the system to adapt its efficiency characteristics to match the current power requirements.

Inventive Principle:

Principle #15Dynamics

2Use of energy by moving object

If the power amplifier operates at low input power levels, then the power consumption is reduced, but the efficiency decreases due to high idling currents

Engineering Contradiction:

Improvepower consumptionVSAvoidamplifier efficiency

Core Design Contradiction:

Use of energy by moving objectVSLoss of energy

Solution Approach 1:

The transmitting output stage is divided into two separate amplification devices: a first power amplifier designed for high power levels and a second power amplifier designed for low power levels. Each amplifier is optimized for its specific power range, with the second amplifier having lower idling current for improved efficiency at low power levels.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system changes the operating parameters by switching between different amplification devices with different idling current characteristics. When low power operation is required, the second amplifier with lower idling current is activated, thereby changing the system's energy consumption profile to match the reduced power requirements.

Inventive Principle:

Principle #35Parameter changes

3Power

If the output stage is designed for maximum power levels, then sufficient transmitting power is guaranteed, but the linearity and data error rate deteriorate at low power levels

Engineering Contradiction:

Improvemaximum transmitting powerVSAvoiddata error rate

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The transmitting output stage is divided into two separate amplification devices with different design optimizations. The first amplifier is optimized for high power operation, while the second amplifier is optimized for low power operation with improved linearity characteristics, ensuring reliable signal transmission at both power levels.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Each amplification device is designed with local quality optimized for its specific operating range. The second amplifier has circuit characteristics specifically tailored for low power operation, including optimized biasing and impedance matching networks that provide superior linearity and signal integrity at low power levels compared to a general-purpose high-power amplifier.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS7486133B2Transmitting output stage with adjustable output power and process for amplifying a signal in a transmitting output stage

Publication Date: 2009.02.03 APPLE INC

AI summary

In one embodiment of a transmitting output stage, a first controllable amplification device with a first amplification factor and a second amplification device with a second amplification factor are provided. The two amplification devices are connected on the input side to a signal input. The transmitting output stage comprises a first matching network, which is connected on the input side to an output of first amplification device. A second matching network is also provided, which is installed switchably between an output of the second amplifier stage and the input of the first matching network and which, in one operating mode of the transmitting output stage in which only the second amplifier stage is being used, is connected between the second amplifier stage and the first matching network. Other embodiments are also disclosed.