CMOS RF Power Detector With Current-Mode ADC for Accurate PA Tracking
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Solution Overview
Problem
Antenna impedance variation significantly impacts the output power and gain of power amplifiers, especially in 5G millimeter wave applications, where existing power detectors require extensive calibration and have low accuracy due to high junction temperatures and the need for multiple power amplifiers operating simultaneously.
Innovation Solution
An electronic circuit comprising a directional coupler, a sense pair connected to the coupler, and an ADC that directly digitizes signal currents from the sense pair, eliminating voltage-to-current conversion errors and minimizing temperature dependency, allowing for accurate power tracking and closed-loop power control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a linear-to-log convertor followed by ADC is used for power detection, then power detection capability is achieved, but measurement precision deteriorates due to extensive calibration requirements and lower accuracy
Solution Approach 1:
The patent extracts and eliminates the linear-to-log convertor from the detection chain, directly connecting the sense pair to the ADC. This removal of the problematic component eliminates the need for extensive calibration while maintaining power detection capability, thereby improving measurement precision without the burden of complex calibration procedures.
Solution Approach 2:
The patent changes the detection parameter from voltage (requiring linear-to-log conversion) to current (directly digitizable). By using a current-mode ADC to directly digitize the sense pair current, the system achieves accurate power detection without the calibration issues inherent in voltage-based detection with linear-to-log convertors.
2Productivity
If multiple power amplifiers operate simultaneously in 5G mm-Wave applications, then high throughput is achieved, but temperature increases causing detection reliability to deteriorate
Solution Approach 1:
The patent implements self-service by making the power detector inherently temperature-insensitive through direct current digitization. The sense pair directly converts RF power to current, which is then directly digitized by the ADC without temperature-sensitive conversion stages. This allows the system to maintain accurate power detection even when multiple PAs operate simultaneously and generate high junction temperatures.
3Adaptability or versatility
If voltage-to-current conversion is used in power detection, then signal adaptation is achieved, but measurement precision deteriorates due to conversion errors
Solution Approach 1:
Instead of converting voltage to current (the conventional approach), the patent inverts the approach by having the sense pair directly generate current from RF power that is then directly digitized. This current-first approach eliminates voltage-to-current conversion errors while maintaining signal adaptability, as the current-mode architecture naturally interfaces with the ADC.
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 solution provides accurate power detection with minimal temperature variation and reduced noise, enabling effective power control across a wide range of antenna impedance variations and high temperatures, improving the performance of 5G millimeter wave power amplifiers.
Implementation Method 1
a directional coupler, a sense pair connected to the directional coupler
Implementation Method 2
converting, with the sense pair, the delivered power to direct current (DC) currents which indicate a power sensed at ports of the coupler
Data Source
AI summary
An electronic device and method are provided. The electronic device includes a directional coupler, a sense pair connected to the directional coupler, and an analog-to-digital converter (ADC) connected to the sense pair. The ADC directly digitizes a signal current received from the sense pair.