Reconfigurable LNA Input Matching via Transistor Parameter Tuning
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Solution Overview
Problem
Existing low-noise amplifiers face challenges in dynamically matching input impedance due to changes over time, such as aging antennas or orientation changes, which lead to impedance mismatches, and prior solutions like physical capacitors or inductors add complexity and noise.
Innovation Solution
A method and circuit that dynamically alter the effective capacitance of an amplifier circuit by changing the on-state of sub-transistors and transconductance of a match transistor, adjusting the equivalent resistance and gain of a cascode transistor to match input impedance, using an adaptive algorithm processor to optimize impedance matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If physical capacitors or inductors are used to compensate for impedance mismatches, then input impedance matching is improved, but device complexity and noise increase
Solution Approach 1:
The patent changes the electrical parameters (capacitance and transconductance) of existing transistors dynamically to achieve impedance matching, rather than adding physical matching components. By adjusting the capacitance of the match transistor and transconductance of the CS transistor, the circuit achieves proper input impedance matching while maintaining simplicity and low noise.
Solution Approach 2:
The amplifier circuit uses its own internal transistors (match transistor and CS transistor) to perform the impedance matching function that would otherwise require external components. The existing transistors serve dual purposes: amplification and impedance matching, eliminating the need for separate matching components and reducing overall circuit complexity.
2Reliability
If physical capacitors or inductors are used to compensate for impedance mismatches, then input impedance matching is improved, but integrated circuit area increases
Solution Approach 1:
The match transistor and CS transistor perform multiple functions simultaneously: they provide both the impedance matching capability and the amplification function. This multi-functionality eliminates the need for separate physical capacitors or inductors, thereby reducing the integrated circuit area while maintaining proper input impedance matching.
Solution Approach 2:
The patent merges the impedance matching function with the amplification function by using the same transistors for both purposes. The match transistor and CS transistor are combined in a configuration where they work together to achieve both impedance matching and signal amplification, reducing the total component count and circuit area.
3Adaptability or versatility
If impedance matching components are added to compensate for aging or orientation changes, then adaptability is improved, but device complexity increases
Solution Approach 1:
The patent implements dynamic impedance matching by allowing the capacitance and transconductance parameters to be adjusted in response to changing conditions such as antenna aging or orientation changes. This dynamic adjustment capability enables the circuit to adapt to varying impedance requirements without requiring complex switching networks or multiple fixed components.
Data Source
AI summary
A method for changing an effective capacitance of an amplifier circuit having a match transistor and a coupled cascode transistor includes changing an on-state of at least one of a plurality of sub-transistors of the match transistor. The method further includes changing a transconductance of the match transistor as a function of the change of the on-state. The method further includes changing an equivalent resistance, as measured between a source and a drain of the cascode transistor, as a function of the change of the transconductance of the match transistor.