LNA Bias Power Supply Circuitry for Stable Current Mirroring
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Solution Overview
Problem
Transistors with short gate lengths used in Low Noise Amplifiers (LNAs) for high-frequency characteristics result in poor pair performance and wide variation in current when forming a current mirror, affecting the stability and accuracy of bias voltage generation.
Innovation Solution
A power supply circuitry that includes a first circuitry generating a first current, a second circuitry generating a second current proportional to the first, and a feedback mechanism to control drive signals based on impedance and reference voltage, allowing for stable bias voltage generation independent of high-frequency transistor gate design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a transistor with a short gate length is used in the LNA to obtain excellent high-frequency characteristics, then high-frequency performance is improved, but pair performance deteriorates and current variation increases
Solution Approach 1:
The patent divides the bias circuit into separate functional blocks: a reference current generation unit using a long-gate transistor for stable reference current, and a current mirror unit using short-gate transistors for high-frequency LNA biasing. This segmentation allows each block to be optimized independently, resolving the contradiction between high-frequency performance and pair performance.
Solution Approach 2:
The patent introduces a reference current source as an intermediary element that decouples the bias generation from the current mirror function. The reference current serves as a stable intermediate value that enables accurate current mirroring without requiring the mirror transistors to have both short gate lengths and excellent pair performance simultaneously.
2Speed
If a transistor with a short gate length is used in the LNA to obtain excellent high-frequency characteristics, then high-frequency performance is improved, but current variation increases
Solution Approach 1:
The patent separates the bias circuit into a reference current generation unit with long-gate transistors for precision and a current mirror unit with short-gate transistors for high-frequency performance. This segmentation allows the reference current to be generated with high precision independently from the high-frequency bias requirements.
Solution Approach 2:
The patent changes the gate length parameter differently for different transistor functions: long gate length for reference current transistors to minimize variation, and short gate length for LNA bias transistors to maximize high-frequency performance. This parameter differentiation resolves the contradiction between current precision and high-frequency characteristics.
3Speed
If transistors are designed for high-frequency characteristics with short gate lengths, then high-frequency performance is improved, but bias voltage stability deteriorates
Solution Approach 1:
The patent segments the bias generation into two independent paths: one generating a stable reference voltage from a long-gate transistor, and another generating the high-frequency LNA bias from short-gate transistors. This segmentation ensures that high-frequency transistors do not compromise bias voltage stability.
Solution Approach 2:
The patent employs feedback mechanisms in the reference current generation unit to stabilize the reference current against variations. This stabilized reference current then serves as a foundation for accurate current mirroring, ensuring bias voltage stability even when using short-gate transistors for high-frequency operation.
Data Source
AI summary
A power supply circuitry includes a first circuitry, a second circuitry, a fourth circuitry, and a fifth circuitry. The first circuitry outputs a first current based on a drive signal. The second circuitry generates a second current according to the first current. The fourth circuitry generates the drive signal based on a first voltage according to the first current. The fifth circuitry outputs a second voltage based on the first current and on the second current.