Power Amplifier Bias Circuit for Mode-Dependent Voltage Control
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Solution Overview
Problem
Power amplifiers in portable terminals face inefficiencies in power usage due to constant bias voltage supply across high and low power modes, leading to increased device volume and reduced continuous operation time.
Innovation Solution
A bias circuit that varies the bias voltage level based on power mode by using a control signal to switch transistors on or off, reducing current consumption in low power mode through a control signal providing unit and varying unit configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the same bias voltage is supplied in both high power mode and low power mode, then the power amplifier can operate in both modes, but power usage efficiency deteriorates and current consumption increases
Solution Approach 1:
The bias voltage is dynamically adjusted based on the operating mode. In high power mode, a first bias voltage is supplied to enable high power amplification, while in low power mode, a second bias voltage different from the first is supplied to reduce current consumption. This dynamic adjustment allows the power amplifier to adapt its power consumption to the actual operating requirements.
Solution Approach 2:
The bias voltage parameter is changed according to the power mode. The control signal varying unit modifies the bias voltage level by controlling the switching of transistors, thereby changing the operating point of the power amplifier to match the current power mode requirements.
2Use of energy by moving object
If different bias circuits are provided for high power mode and low power mode, then power usage efficiency improves, but circuit area increases leading to increased device volume
Solution Approach 1:
A single bias circuit is designed to perform multiple functions by supplying different bias voltages depending on the power mode. The bias circuit includes a control signal providing unit and a control signal varying unit that can generate and adjust the appropriate bias voltage for either high power mode or low power mode operation, eliminating the need for separate bias circuits.
Solution Approach 2:
The control signal providing unit and control signal varying unit are combined into a unified bias circuit structure. This integrated approach merges the functions of bias generation and bias adjustment into a single circuit block, reducing the overall circuit area while maintaining the capability to provide mode-dependent bias voltages.
3Volume of moving object
If a single bias circuit supplies different bias voltages for different power modes, then device volume is reduced, but the complexity of bias voltage control increases
Solution Approach 1:
A control signal is introduced as an intermediary to manage the bias voltage switching between different power modes. The control signal varying unit receives the control signal and uses it to adjust the bias voltage level by controlling transistor switching, thereby simplifying the overall control architecture while enabling mode-dependent bias adjustment.
Solution Approach 2:
The bias circuit automatically adjusts the bias voltage based on the power mode without requiring external intervention. The control signal varying unit monitors the power mode and self-adjusts the bias voltage level by controlling the switching state of transistors within the circuit.
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.