Symmetrical Bias Circuit Layout for Low-Power Amplifier Linearity
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Solution Overview
Problem
Power amplifiers in wireless communications devices experience thermal imbalance and non-linearity of output signals when operated in low power mode due to asymmetrical transistor arrangements, leading to inefficiencies in power consumption.
Innovation Solution
A power amplifier design featuring transistors divided into two groups with separate bias circuits, where each group receives bias power through distinct ballast resistors, forming a symmetrical array to balance thermal distribution and improve signal linearity, with each transistor being a heterojunction bipolar transistor amplifying input signals between input and output terminals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If bias power is supplied to some transistors in low power mode, then power consumption efficiency is improved, but thermal imbalance occurs and non-linearity of output signals is caused
Solution Approach 1:
The patent applies asymmetry in reverse - it creates a symmetrical structure where transistors are divided into first and second groups with corresponding first and second bias circuits. The bias circuits are disposed at positions symmetrical to each other in relation to the transistors, ensuring that when bias power is supplied to one group, the other group remains in a complementary state. This symmetrical arrangement prevents thermal imbalance and maintains signal linearity while still enabling power consumption efficiency improvements through selective biasing of transistor groups.
2Use of energy by moving object
If bias power is supplied to some transistors in low power mode, then power consumption efficiency is improved, but thermal imbalance occurs
Solution Approach 1:
The patent segments the transistor array into two distinct groups: first transistors and second transistors. Each group is controlled by its own dedicated bias circuit (first bias circuit and second bias circuit respectively). This segmentation allows independent control of bias power supply to each group, enabling the power amplifier to selectively activate one group while keeping the other in a low-power state, thereby improving overall power consumption efficiency while maintaining thermal balance through the symmetrical arrangement of these segmented components.
Data Source
AI summary
A power amplifier includes an amplifying circuit configured to amplify an input signal and comprising transistors, which may be disposed in parallel with one another and divided into a first group of transistors and a second group of transistors. The power amplifier also includes a bias circuit configured to supply bias power to one of the transistors of the first group and the transistors of the second group.