PA Self-Heating Tracking Circuit for Thermal Time Constant Estimation
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Solution Overview
Problem
Self-heating effects in FinFET and SOI devices cause thermal memory effects and limit the performance of on-chip power amplifiers due to asymmetry in heating and cooling time constants, which existing methods struggle to accurately estimate.
Innovation Solution
A self-heating tracking circuit with a PA replica circuit and an estimation unit that estimates the self-heating time constant by turning the replica circuit on and off, using a first-order single-pole model or step response models, to track the temperature of the PA and overcome thermal memory effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If self-heating tracking is implemented using a PA replica circuit, then measurement precision of self-heating time constant is improved, but device complexity increases
Solution Approach 1:
A PA replica circuit is created that replicates the thermal characteristics of the actual power amplifier. The replica circuit includes transistors positioned in proximity to the PA transistors to experience the same self-heating effects, allowing indirect measurement of temperature and time constant without directly measuring the PA itself.
Solution Approach 2:
The PA replica circuit serves as an intermediary between the actual PA and the measurement system. By measuring the replica circuit's response to self-heating, the system indirectly obtains accurate time constant data without requiring direct access to or modification of the actual PA's internal temperature sensors.
2Measurement precision
If PA replica circuit is placed in proximity to track temperature, then temperature tracking accuracy is improved, but manufacturing precision requirements increase
Solution Approach 1:
The replica circuit transistors are positioned in specific local regions adjacent to the PA transistors where thermal coupling is maximized. This localized positioning ensures that the replica experiences the same thermal environment as the PA, improving temperature tracking accuracy while minimizing the impact of broader manufacturing variations.
3Measurement precision
If estimation unit uses multiple models (first-order single-pole, rising step, falling step), then measurement precision is improved, but device complexity increases
Solution Approach 1:
The estimation unit dynamically selects and applies different mathematical models (first-order single-pole, rising step response, falling step response) based on the operating conditions and available data. This dynamic approach allows the system to adapt to varying thermal scenarios and improve estimation accuracy without requiring a single overly complex fixed model.
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
Enables accurate estimation of the self-heating time constant, allowing for the development of circuits and algorithms that mitigate self-heating effects and enhance the performance of power amplifiers in FinFET and SOI devices.
Implementation Method 1
a PA replica circuit in proximity to the PA such that a temperature of the PA replica circuit tracks with a temperature of the PA
Data Source
AI summary
Embodiments of self-heating tracking circuits for a power amplifier (PA) are disclosed. In an embodiment, a self-heating tracking circuit for a PA includes a PA replica circuit in proximity to the PA and an estimation unit configured to estimate a self-heating time constant of the PA in response to turning on the PA replica circuit and turning off the PA replica circuit.