Power Amplifier Bias Circuit With Delayed Switching Startup
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Solution Overview
Problem
Typical power amplifier bias circuits experience a time delay between receiving a reference voltage and operating, which lowers response speed and linearity, especially in time division duplexing systems requiring dynamic operation modes.
Innovation Solution
A bias circuit with a switching control circuit that transmits a switching signal after a preset delay time, forming a current path between the output node and ground to reduce the amplitude of the bias signal, thereby improving response speed and linearity by providing a higher bias at the initial driving time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a typical power bias circuit is used to generate temperature-compensated bias voltage, then temperature compensation is achieved, but response speed is lowered due to time delay
Solution Approach 1:
The switching control circuit generates a switching signal in advance based on a driving start signal, activating the switching circuit before the bias signal would naturally become available. This preliminary action eliminates the time delay by pre-establishing the current path through the switching circuit, allowing the power amplifier to operate immediately without waiting for the bias circuit to stabilize.
Solution Approach 2:
The switching circuit acts as an intermediary between the bias circuit and ground, controlling the current path dynamically. By using the switching circuit as a mediator, the system can bypass the time delay inherent in the bias circuit generation process, as the switching circuit can be activated independently and immediately to establish the necessary current path.
2Stability of the object's composition
If a typical power bias circuit is used to generate temperature-compensated bias voltage, then temperature compensation is achieved, but linearity is decreased due to time delay
Solution Approach 1:
The switching control circuit generates a switching signal in advance based on a driving start signal, activating the switching circuit before the bias signal would naturally become available. This preliminary action eliminates the time delay by pre-establishing the current path through the switching circuit, allowing the power amplifier to operate immediately without waiting for the bias circuit to stabilize.
Solution Approach 2:
The switching circuit acts as an intermediary between the bias circuit and ground, controlling the current path dynamically. By using the switching circuit as a mediator, the system can bypass the time delay inherent in the bias circuit generation process, as the switching circuit can be activated independently and immediately to establish the necessary current path.
3Speed
If the switching circuit operates to reduce bias signal amplitude after delay time, then response speed is improved, but circuit complexity increases
Solution Approach 1:
The bias circuit is segmented into functional modules: a bias circuit for generating the bias signal, a switching control circuit for generating the switching signal, and a switching circuit for controlling the current path. This segmentation allows each module to be optimized independently, with the switching control circuit being a relatively simple delay and control unit that does not significantly increase overall system complexity.
Solution Approach 2:
The switching control circuit acts as a simple intermediary that receives the driving start signal, applies a preset delay, and generates the switching signal. This intermediary function is implemented using basic electronic components (delay circuit, logic gates) rather than complex control mechanisms, thereby minimizing the increase in circuit complexity while achieving the desired response speed improvement.
Data Source
AI summary
A power amplifier circuit includes a bias circuit and an amplifier circuit. The bias circuit includes a first bias circuit to receive a reference voltage and an operation voltage and generate a first bias signal, a bias supply circuit to transmit the base bias signal to a base of a power amplifier, based on the first bias signal input from the first bias circuit, a switching control circuit to transmit a switching signal after a preset delay time based on a driving start signal, and a switching circuit connected between an output node of the first bias circuit and a ground, to operate in an ON state after the delay time in response to the switching signal to form a current path between the output node of the first bias circuit and the ground.