Power Amplifier Temperature Correction for Dynamic Thermal Biasing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Traditional static Error Vector Magnitude (EVM) calculations for power amplifiers do not account for dynamic thermal behavior, which is crucial in Time Division Duplex (TDD) systems and flip chip packages, especially when targeting low DEVM levels in wide temperature range bipolar power amplifiers.
Innovation Solution
A temperature correction circuit and method that provide a reference current to maintain a power amplifier transistor in a linear operating region by using a combination of first and second correction currents proportional to absolute and changing temperatures, along with a gain selection current, to account for static and dynamic temperature variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional static EVM calculations are used for power amplifiers, then the calculation is simple and based on AM/AM and AM/PM distortions, but it does not capture the dynamic thermal behavior which is important in TDD systems and flip chip packages
Solution Approach 1:
The temperature correction circuit is segmented into two independent sub-circuits: a static temperature sub-circuit that handles absolute temperature correction using a first correction current, and a dynamic temperature sub-circuit that handles temperature changes using a second correction current. This segmentation allows each sub-circuit to be optimized for its specific function while maintaining overall system manageability and accuracy.
Solution Approach 2:
The patent introduces temperature correction currents as intermediary elements that mediate between the temperature variations (static and dynamic) and the power amplifier transistor operation. These correction currents serve as intermediaries that translate temperature effects into electrical corrections, enabling precise control of the transistor's operating point without directly measuring or controlling temperature.
2Reliability
If dynamic thermal behavior is captured in EVM calculations, then DEVM levels can be reduced, but the calculation and correction system becomes more complex
Solution Approach 1:
The patent implements dynamic temperature correction by introducing a dynamic temperature sub-circuit that responds to temperature changes during operation. This sub-circuit generates a second correction current proportional to the temperature change, allowing the system to adapt to dynamic thermal conditions in real-time, thereby stabilizing power gain and reducing DEVM levels.
Solution Approach 2:
The temperature correction circuit employs feedback mechanisms where the output of the dynamic temperature sub-circuit is fed back to adjust the reference current in real-time. This feedback loop continuously monitors and compensates for temperature-induced variations in transistor characteristics, ensuring stable power amplifier operation across varying thermal conditions.
3Device complexity
If a single reference current is used for temperature correction, then the circuit is simplified, but it must handle both static and dynamic temperature variations simultaneously
Solution Approach 1:
The patent merges the static and dynamic temperature correction functions into a unified reference current output. The static temperature sub-circuit and dynamic temperature sub-circuit both contribute to the same reference current that biases the power amplifier transistor, allowing simultaneous handling of both static and dynamic temperature variations through a single integrated correction mechanism.
Solution Approach 2:
The reference current serves multiple functions: it provides the bias current for the power amplifier transistor, incorporates static temperature correction, and integrates dynamic temperature compensation. This multi-functional design allows a single current to handle both absolute temperature effects and temperature changes, reducing the need for separate correction paths while maintaining comprehensive temperature coverage.
Data Source
AI summary
A temperature correction circuit and method for maintaining a transistor of a power amplifier in a linear operating region of the transistor. The temperature correction circuit includes a first current source circuit operable to provide a first correction current proportional to an absolute temperature of a semiconductor die including the transistor. The temperature correction circuit also includes a second current source circuit operable to provide a second correction current proportional to a change in temperature of a part of the semiconductor die in which the transistor is located during operation of the transistor. The temperature correction circuit further includes a third current source circuit operable to provide a gain selection current. The temperature correction circuit also includes circuitry for producing a reference current from the first and second correction currents and the gain current. The temperature correction circuit further includes an output for providing the reference current to the transistor.