Doherty Photodiode Amplification for OFDM Back-Off Efficiency
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Solution Overview
Problem
The existing radio frequency photonic base stations face challenges in improving back-off efficiency while maintaining the linear dynamic range, particularly due to the high peak-to-average ratio of OFDM signals.
Innovation Solution
A photoelectric amplification circuit utilizing a Doherty circuit structure based on a high-power photodiode, combined with an impedance modulation unit, to enhance power supply efficiency and implement dynamic load conversion from a back-off point to a maximum output point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a high-power photodiode is used in a radio frequency photonic front end to replace the power amplifier, then ultra-wideband and miniaturization are achieved, but power supply efficiency deteriorates in back-off states
Solution Approach 1:
The patent divides the single photodiode into multiple photodiodes operating in parallel, where each photodiode can be independently controlled. This segmentation allows the system to activate only the necessary number of photodiodes based on the input signal power, thereby improving power supply efficiency in back-off states while maintaining the compact form factor
Solution Approach 2:
The patent implements dynamic impedance modulation and power control for each photodiode based on the input signal characteristics. The impedance modulation unit dynamically adjusts the impedance of each photodiode according to the signal power level, enabling the system to adapt to different operating states and maintain high efficiency across the full frequency band
2Productivity
If OFDM technology is used to maximize spectral efficiency, then system capacity increases, but the high peak-to-average ratio imposes stricter requirements on the linear dynamic range
Solution Approach 1:
The patent employs dynamic impedance modulation that adapts to the instantaneous signal power level. By continuously adjusting the impedance of each photodiode based on the input signal characteristics, the system maintains optimal linear operation even during high peak power conditions, thereby supporting OFDM signals with high peak-to-average ratios
Solution Approach 2:
The patent changes the operating parameters (impedance and power level) of each photodiode dynamically based on the input signal power. This parameter adaptation allows the system to maintain linearity across a wide dynamic range while preserving the high spectral efficiency of OFDM modulation
3Loss of energy
If back-off efficiency is improved for high-power photodiodes, then power consumption is reduced, but output efficiency may deteriorate in the interval between maximum power point and back-off point
Solution Approach 1:
The patent segments the total output power requirement across multiple photodiodes, allowing the system to operate multiple photodiodes at moderate power levels rather than forcing a single photodiode to operate at high power. This segmentation maintains higher output efficiency across the power range from back-off to maximum point
Solution Approach 2:
The patent implements continuous impedance modulation that adjusts the operating point of each photodiode dynamically. By optimizing the impedance parameter across the power range, the system maintains high output efficiency for each photodiode while achieving overall power reduction through selective activation and modulation
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
The proposed solution improves the power supply efficiency of the high-power photodiode in a back-off state, maintains high output efficiency across a wide range, and reduces costs by enabling flexible deployment of services across the full frequency band of a base station.
Implementation Method 1
The first photodiode includes a first input end and a first output end. The first input end is configured to receive a first optical signal, and the first output end is configured to output a first radio frequency signal
Data Source
AI summary
This application provides a photoelectric amplification circuit and a signal processing method. The photoelectric amplification circuit includes a first photodiode and a second photodiode that are connected in parallel. A Doherty circuit structure is used, so that power supply efficiency of the photodiode in a back-off state can be improved. In addition, an impedance modulation unit is used, to implement dynamic load conversion from a back-off point to a maximum output point. This helps maintain high output efficiency of the first photodiode and the second photodiode in an interval between the maximum power point and the back-off point.