Doherty Power Amplifier Gain Control Across Power Modes
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Solution Overview
Problem
Doherty amplifier circuits face inefficiencies in low power modes due to high impedance, leading to higher gain but increased power consumption, and existing solutions do not adequately address the need to adjust gain according to power modes.
Innovation Solution
A power amplifier circuit design that includes a splitter to split the input signal into two paths, with specific amplifiers and impedance elements connected to biasing circuits, allowing for three power modes (high, low, and middle power) by controlling bias currents/voltages to adjust gain and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the Doherty amplifier operates in low power mode with high impedance, then the gain is improved, but the power consumption increases
Solution Approach 1:
The patent applies dynamics by making the impedance state changeable according to power mode. The impedance transformation network dynamically adjusts the impedance seen by the carrier amplifier based on whether the system is in high power mode or low power mode, allowing optimal gain in each mode while managing power consumption through controlled impedance states.
Solution Approach 2:
The patent changes the impedance parameter of the amplifier circuit based on power mode requirements. By transforming the impedance state between high power mode and low power mode, the system achieves different gain characteristics appropriate for each operating condition, resolving the contradiction between gain improvement and power consumption.
2Loss of energy
If the Doherty amplifier circuit uses a carrier amplifier and peak amplifier connected in parallel, then the efficiency is improved at high power levels, but the circuit complexity increases
Solution Approach 1:
The patent segments the amplifier function into a carrier amplifier and a peak amplifier that operate in different conditions. The carrier amplifier handles continuous operation while the peak amplifier activates only when needed for high power levels, dividing the overall amplification function to achieve high efficiency without requiring both amplifiers to operate simultaneously, thus managing complexity.
Solution Approach 2:
The carrier amplifier serves multiple functions: it operates continuously for low power modes and also contributes to high power output when combined with the peak amplifier. This multi-functionality reduces the need for separate dedicated components for each power level, managing circuit complexity while maintaining efficiency across different power levels.
3Measurement precision
If the impedance is increased in low power mode, then the gain of the Doherty amplifier is improved, but the power consumption increases
Solution Approach 1:
The patent makes the impedance dynamic by using an impedance transformation network that adjusts the impedance state based on power mode. In low power mode, the network transforms to provide high impedance for improved gain, while in high power mode it adjusts to a different impedance state, allowing the system to achieve high gain when needed without permanently maintaining the high impedance state that would cause excessive power consumption.
Solution Approach 2:
The patent changes the impedance parameter dynamically based on operating conditions. The impedance transformation network modifies the impedance value according to whether the system is in high power mode or low power mode, enabling the circuit to achieve optimal gain characteristics in each mode while avoiding the power consumption penalty of maintaining high impedance continuously.
Data Source
AI summary
There is provided a power amplifier circuit capable of adjusting the gain according to the power mode. A power amplifier circuit includes: a splitter outputting an input signal by splitting the input signal to a signal RF1 and a signal RF2; amplifiers connected to the splitter; and an amplifier provided in or on a signal path branching from between the splitter and an input of the amplifier, connected in parallel with the amplifier, and connected to a biasing terminal supplied with a third bias current or voltage.