Envelope-Tracked Doherty Power Amplifier for Back-Off Efficiency
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Solution Overview
Problem
Existing power amplification systems in base stations face limited efficiency improvement when dealing with signals having high peak-to-average power ratios, leading to increased energy consumption and reduced saturation power due to the use of power back-off methods.
Innovation Solution
The implementation of a power amplification apparatus where an envelope voltage is shared between main and auxiliary power transistors, allowing simultaneous adjustment of operating voltages and enabling envelope tracking, thereby enhancing efficiency and saturation power by combining Doherty amplifier efficiency advantages with envelope tracking technology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If power back-off method is used to amplify signals with high peak-to-average power ratio, then linearity of power amplifier is improved, but power amplification efficiency greatly decreases
Solution Approach 1:
The power amplifier is divided into two independent amplifiers: main power amplifier and auxiliary power amplifier. Each amplifier operates independently with its own operating voltage control, allowing the main amplifier to handle peak signals with high linearity while the auxiliary amplifier supplements during back-off conditions, thereby maintaining overall efficiency.
Solution Approach 2:
The invention dynamically adjusts the operating voltages of both main and auxiliary power amplifiers based on the input signal characteristics. The envelope modulator provides dynamic voltage control to track the signal envelope, enabling the amplifiers to transition between different operating states (linear and saturated) according to real-time signal conditions, thus optimizing both linearity and efficiency.
2Power
If fixed voltage is used to supply power to auxiliary power amplifier in Doherty amplifier, then saturation power is limited by breakdown voltage of power transistor, but efficiency during back-off is improved
Solution Approach 1:
The invention replaces fixed voltage supply with dynamic envelope tracking voltage supply for the auxiliary power amplifier. The envelope modulator generates a time-varying voltage that tracks the signal envelope, allowing the auxiliary amplifier to operate efficiently during back-off while enabling higher saturation power by adjusting voltage according to transistor breakdown limits rather than being constrained by a fixed voltage level.
Solution Approach 2:
The operating voltage of the auxiliary power amplifier is changed from a fixed parameter to a dynamically variable parameter that follows the signal envelope. This parameter change allows the amplifier to adapt its operating point, maintaining efficiency during back-off conditions while enabling higher power output when needed, thus resolving the contradiction between saturation power and back-off efficiency.
3Use of energy by moving object
If ratio of voltage of main power amplifier to voltage of auxiliary power amplifier is larger, then efficiency during back-off is improved, but symmetry of Doherty amplifier is reduced causing efficiency loss
Solution Approach 1:
The invention dynamically balances the voltages of main and auxiliary power amplifiers through envelope tracking. Both amplifiers receive voltages that track the signal envelope proportionally, maintaining a balanced voltage ratio that preserves symmetry. This dynamic balancing allows efficiency improvement during back-off while preventing the symmetry loss that occurs with fixed large voltage ratios.
Data Source
AI summary
A power amplification apparatus, a remote radio unit, and a base station are provided to improve power amplification efficiency. The power amplification apparatus includes an envelope modulator, a main power amplifier, and a first auxiliary power amplifier. The envelope modulator is configured to obtain an envelope voltage based on a received envelope signal and output the envelope voltage to the drain of the main power amplifier. The main power amplifier is connected to the envelope modulator and configured to use the envelope voltage as an operating voltage, and is connected to the first auxiliary power amplifier, to output the envelope voltage to a drain of the first auxiliary power amplifier. The first auxiliary power amplifier is configured to use the envelope voltage received from the main power amplifier as an operating voltage.