Dual-Gate Power Amplifier Biasing for Linearity and Temperature Stability
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Solution Overview
Problem
Existing power amplifier technologies face challenges in simultaneously applying analog pre-distortion and temperature compensation bias, particularly due to the difficulty in adding high-bandwidth and dynamic-range voltage signals without compromising performance, especially when operating over a large temperature range.
Innovation Solution
The use of a constant transconductance bias circuit that applies temperature compensation signals to the back gates of power amplifier transistors, while analog linearization signals are applied to the gates, allowing for effective tracking of temperature variations and maintaining linear output characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If analog linearization method is used to vary the bias voltage with high bandwidth and temperature regulating bias circuit is used to change the bias voltage relatively slowly, then both linearity and temperature stability should be improved, but adding these two voltages becomes challenging and performance of at least one bias control is compromised
Solution Approach 1:
The patent divides the single bias control function into two independent circuits: an analog linearization bias circuit that operates at high bandwidth for linearity control, and a temperature regulating bias circuit that operates slowly for temperature stability. By segmenting the bias control into separate functional blocks, each circuit can optimize its performance without interfering with the other, thus resolving the contradiction between reliability and device complexity.
2Manufacturing precision
If both analog pre-distortion and temperature compensation bias are applied simultaneously, then linearity and temperature stability should be improved, but the difficulty in adding high-bandwidth and dynamic-range voltage signals increases
Solution Approach 1:
The patent applies segmentation by separating the linearity control (analog pre-distortion) and temperature stability control (temperature compensation bias) into independent bias circuits. This allows each function to be implemented with optimized signal characteristics without the complexity of combining high-bandwidth and dynamic-range voltage signals in a single circuit, thus resolving the contradiction between manufacturing precision and device complexity.
3Adaptability or versatility
If PA operates over large temperature range, then adaptability is improved, but PA characteristics change substantially making control difficult
Solution Approach 1:
The patent implements feedback through a temperature sensor that continuously monitors the PA temperature and feeds this information back to the temperature regulating bias circuit. This closed-loop feedback mechanism allows the bias circuit to automatically adjust and compensate for temperature-induced characteristic changes, maintaining reliable PA operation across a large temperature range and resolving the contradiction between adaptability and reliability.
Data Source
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AI summary
A power amplifier arrangement comprises a power amplifier comprising at least one transistor having a first gate and a second gate. The first gate is configured to receive a radio frequency input signal superimposed with a first control signal, and the second gate is configured to receive a second control signal. The first control signal is a linearization signal varying in relation to an envelope of the input signal and the second control signal is a temperature compensation signal varying in relation to a temperature of the power amplifier, or vice versa.