Embedded PA Sensor Bias Control for Dynamic EVM Correction
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Solution Overview
Problem
In RF applications, particularly in WLAN power amplifiers operating in a pulsed on and off mode, thermo-electric effects degrade dynamic error vector magnitude (DEVM) performance, which existing technologies fail to effectively address.
Innovation Solution
A power amplifier (PA) with an embedded sensor, similar to the amplification transistors, is used to sense operating conditions like temperature, isolated from RF signals, and a bias circuit compensates for DEVM effects by adjusting base bias voltages based on the sensed collector current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a power amplifier operates in pulsed on and off mode to reduce current consumption, then energy efficiency is improved, but thermo-electric effects degrade dynamic error vector magnitude performance
Solution Approach 1:
The patent applies preliminary action by measuring the junction temperature of the power amplifier transistor before switching off during pulsed operation. This temperature measurement is obtained in advance using an embedded temperature sensor, allowing the system to compensate for thermal effects before they degrade DEVM performance. The bias circuit adjusts bias voltages based on this pre-measured temperature data, preventing thermo-electric degradation while maintaining energy efficiency.
2Reliability
If an embedded sensor is added to sense operating conditions of amplification transistors, then DEVM compensation capability is improved, but device complexity increases
Solution Approach 1:
The patent merges the temperature sensing function directly into the power amplifier transistor structure by embedding a temperature sensor at or near the transistor junction. This integration allows the sensor to share the same physical space and thermal environment as the amplification transistor, enabling accurate temperature measurement without adding separate external sensing components. The bias circuit also integrates the temperature compensation function, combining multiple functions into unified circuit blocks.
Solution Approach 2:
The patent introduces a temperature sensor as an intermediary element that mediates between the amplification transistor and the bias circuit. The sensor converts the thermal state of the transistor into an electrical signal that the bias circuit can process, enabling indirect temperature measurement without requiring direct physical contact or complex measurement techniques. This intermediary approach simplifies the overall system architecture.
3Measurement precision
If the sensor is positioned close to amplification transistors to accurately sense operating conditions, then measurement precision is improved, but the sensor may be affected by RF signals
Solution Approach 1:
The patent extracts the temperature sensing function from the RF signal path by using a dedicated temperature sensor that measures only thermal conditions. The sensor is positioned to thermally couple with the amplification transistor junction, allowing it to sense the exact temperature at the transistor while being electrically isolated from RF signals. This separation of thermal sensing from RF signal processing eliminates interference while maintaining measurement accuracy.
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
This solution effectively compensates for DEVM effects independently of supply power, duty cycle, temperature, and layout, maintaining normal gain expansion characteristics at high RF power without affecting RF signal amplification.
Implementation Method 1
Such an operation can result in thermo-electric effects that can degrade dynamic error vector magnitude (DEVM) performance
Implementation Method 2
The array is configured to receive and amplify a radio-frequency (RF) signal
Data Source
AI summary
Devices and methods related to embedded sensors for dynamic error vector magnitude corrections. In some embodiments, a power amplifier (PA) can include a PA die and an amplification stage implemented on the PA die. The amplification stage can include an array of amplification transistors, with the array being configured to receive and amplify a radio-frequency (RF) signal. The PA can further include a sensor implemented on the PA die. The sensor can be positioned relative to the array of amplification transistors to allow sensing of an operating condition representative of at least some of the amplification transistors. The sensor can be substantially isolated from the RF signal.