Switchable Bias Circuit for Multi-Mode Power Amplifiers
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Solution Overview
Problem
Existing power amplifiers compatible with 2G, 3G, and 4G modes can only realize optimal performance in one mode due to fixed bias currents, limiting their efficiency and linearity across different communication standards.
Innovation Solution
A bias circuit with a first and second branch circuit, a current amplifier, and a switch that adjusts resistance values to provide different bias currents to the power amplifier, allowing optimal performance in multiple modes by changing the radio frequency impedance and bias current based on switching states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed bias circuit is used to provide a base bias current, then the power amplifier can operate in different modes (2G, 3G, 4G), but the power amplifier cannot achieve optimal performance in all modes simultaneously due to fixed bias current
Solution Approach 1:
The bias circuit transitions from a fixed configuration to a dynamic one by introducing a switch that can change the resistance value in the bias network. This allows the bias current to be adjusted between different levels (first bias current for 2G mode, second bias current for 3G/4G mode), enabling the power amplifier to achieve optimal performance in each operating mode while maintaining versatility across multiple standards
Solution Approach 2:
The invention changes the electrical parameter (resistance) in the bias circuit through the switch, which directly controls the bias current magnitude. By switching between different resistance values, the bias current is dynamically adjusted to match the requirements of different communication modes, resolving the contradiction between mode compatibility and performance optimization
2Power
If a large bias current is provided for 2G mode operation, then the power amplifier achieves better output power and linearity, but the efficiency decreases when operating in 3G or 4G modes
Solution Approach 1:
The bias circuit dynamically adjusts the bias current level based on the operating mode. In 2G mode, the switch configures the circuit to provide a large bias current for optimal output power and linearity. In 3G/4G mode, the switch reconfigures the circuit to provide a smaller bias current, thereby improving efficiency. This dynamic adjustment resolves the contradiction between power performance and energy efficiency across different modes
Solution Approach 2:
The invention changes the bias current parameter by switching the resistance value in the bias network. The switch enables transitions between a first bias current level (optimized for 2G power and linearity) and a second bias current level (optimized for 3G/4G efficiency), allowing the system to adapt the electrical parameter to match mode-specific requirements and eliminate the trade-off between power and efficiency
3Use of energy by moving object
If a small bias current is provided for 3G or 4G mode operation, then the efficiency improves, but the output power and linearity deteriorate when operating in 2G mode
Solution Approach 1:
The bias circuit uses a switch to dynamically reconfigure the resistance value based on the operating mode. When operating in 3G/4G mode, the switch sets the circuit to provide a small bias current for high efficiency. When switching to 2G mode, the same circuit dynamically adjusts to provide a large bias current for optimal output power and linearity. This dynamic adaptability resolves the contradiction between efficiency and power performance
Solution Approach 2:
The invention implements parameter changes in the bias current by switching the resistance value in the bias network. The switch enables the bias current to transition between a first level (small current for 3G/4G efficiency) and a second level (large current for 2G power and linearity). This parameter adjustment capability allows the system to optimize for either efficiency or power/linearity depending on the operating mode, eliminating the performance deterioration
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables flexible control of bias currents for power amplifiers, improving performance across 2G, 3G, and 4G modes by adjusting impedance and reducing memory effects in broadband modulation signals, thus enhancing radio frequency signal amplification.
Implementation Method 1
The current amplifier is configured to receive the second branch current, amplify the second branch current, and output the amplified second branch current as a bias current of a power amplifier connected to the bias circuit. The current amplifier includes a transistor.
Implementation Method 2
The switch is configured to switch different resistance values for a resistor in the first branch circuit, and/or switch different resistance values for a resistor in the second branch circuit.
Data Source
AI summary
A bias circuit includes a first branch circuit, a second branch circuit, a current amplifier and a switch, wherein the first branch circuit is configured to shunt an inputted first current, and input a first branch current of the first current to a power supply ground; the second branch circuit is configured to shunt the inputted first current, and input a second branch current of the first current to the current amplifier; the current amplifier is configured to receive the second branch current of the first current and amplify the second branch current of the first current to serve as a bias current of a power amplifier connected to the bias circuit for outputting; and the switch is configured to switch different resistance values for a resistor in the first branch circuit and/or switch different resistance values for a resistor in the second branch circuit.