Power Amplifier Bias Circuit for Mode-Dependent Bias Voltage
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Solution Overview
Problem
Existing power amplifiers in portable terminals inefficiently use power due to the same bias voltage being applied in both high and low power modes, leading to increased device size and reduced continuous operation time.
Innovation Solution
A bias circuit that varies the bias voltage level based on the power mode by using a control signal to switch a bias supplying transistor, reducing current consumption in low power mode through a control signal providing unit and varying unit configuration with transistors and resistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the same bias voltage is applied in both high power mode and low power mode, then the power amplifier can maintain consistent performance across modes, but power usage efficiency deteriorates and current consumption increases
Solution Approach 1:
The bias voltage is dynamically adjusted based on the operating mode (high power or low power) through a control signal that switches between different voltage levels. The bias setting unit changes the voltage level of the control signal according to the power mode, enabling the bias supplying transistor to provide appropriate bias voltage for each mode, thereby improving power efficiency while maintaining performance consistency.
2Use of energy by moving object
If different bias circuits are provided for high power mode and low power mode, then power usage efficiency is improved, but circuit area increases
Solution Approach 1:
A single bias supplying transistor is designed to perform multiple functions by switching between different operating states based on the control signal. The same transistor provides different bias voltage levels (first bias voltage for high power mode, second bias voltage for low power mode) depending on the power mode signal, eliminating the need for separate bias circuits for each mode while maintaining power efficiency.
Solution Approach 2:
The bias voltage parameter is changed based on the power mode through a control signal generated by the bias setting unit. The control signal's voltage level is varied according to whether the amplifier is in high power or low power mode, causing the bias supplying transistor to adjust its output accordingly. This parameter change approach enables efficient power usage without requiring additional circuit components.
Data Source
AI summary
A bias circuit providing different bias voltages depending on a power mode through a simple circuit, and a power amplifier having the same are provided. The bias circuit and the power amplifier include a bias setting unit configured to vary a voltage level of a control signal controlling a bias voltage according to an operation of a first transistor being switched-off in a high power mode and switched-on in a low power mode. A bias supplying unit includes a bias supplying transistor switched based on the control signal, to supply the bias voltage having a voltage level according to a switching operation of the bias supplying transistor.