Wireless Transmitter Crest-Factor EVM Control for Higher Output Power
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Solution Overview
Problem
Wireless communication devices face challenges in maintaining sufficient transmission power while minimizing interference with other frequency channels, often resulting in excessive power backoff that decreases transmission power.
Innovation Solution
A transmitter system with a digital power meter, output power detector, and control circuitry that determines an estimated and amplified crest factor ratio to adjust the amplification factor, allowing for increased transmission power without entering nonlinear regions and causing excessive emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If power backoff is applied to prevent interference with other frequency channels, then interference with other channels is reduced, but transmission power decreases
Solution Approach 1:
The system implements a feedback mechanism where the output signal from the amplifier is monitored by an output power detector. The detector measures the actual output power and feeds this information back to the control circuitry, which adjusts the amplifier's operation to maintain optimal power levels while minimizing interference with other frequency channels.
Solution Approach 2:
The patent replaces traditional mechanical power control mechanisms with electronic detection and control systems. Specifically, it uses a digital power meter to measure input power, an output power detector to measure output power, and control circuitry to electronically adjust the amplifier's amplification factor, eliminating the need for manual or mechanical power adjustment.
2Power
If amplification factor is increased to improve transmission power, then transmission power increases, but the amplifier enters nonlinear regions causing excessive emissions
Solution Approach 1:
The control circuitry continuously monitors the output signal characteristics and adjusts the amplification factor in real-time. When the amplifier approaches nonlinear operation, the feedback mechanism detects this and reduces the amplification factor to prevent excessive emissions, while still maintaining high transmission power within the linear operating region.
Solution Approach 2:
The system dynamically adjusts the amplification factor based on real-time operating conditions rather than using a fixed value. The control circuitry modifies the amplification factor continuously to keep the amplifier operating in its linear region, optimizing both transmission power and emission levels according to the actual signal conditions.
Data Source
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Figure 3
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AI summary
An amplifier of a transmitter includes an input that receives an input signal and generates an amplified signal at an output. A digital power meter is coupled to the input of the amplifier, generates an estimated amplified signal, and determines peak and average powers of the estimated amplified signal. An output power detector coupled to the output of the amplifier determines peak and average powers of the amplified signal. A controller coupled to the digital power meter and the output power detector determines an estimated crest factor based on the peak and average powers of the estimated amplified signal, an amplified crest factor based on the peak and average powers of the amplified signal, and an error vector magnitude based on the estimated and amplified crest factors. The controller, which is also coupled to the amplifier, then adjusts operation of the amplifier based on the error vector magnitude.