Multi-Band LNA Inductor Reuse for Compact Low-Noise RF Front Ends
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Solution Overview
Problem
Existing multi-band low noise amplifiers (LNAs) face challenges in efficiently reusing inductors across different frequency bands, leading to increased chip area and degradation of signal quality due to spurs, noise figure, and gain issues.
Innovation Solution
A multi-band LNA design that reuses at least one input impedance matching inductor and one load inductor for both narrowband and wideband operations, utilizing a common source and common gate configuration with a tapped-capacitance or tapped-inductor impedance matching network, and a switched capacitor network to tune resonance frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple separate inductors are used for different frequency bands, then each band can be optimized independently, but chip area increases significantly
Solution Approach 1:
The patent implements inductor reuse across multiple frequency bands by designing the LNA to operate in different configurations (common source for narrowband, common gate for wideband) while sharing the same input and load inductors. This multi-functional approach allows a single inductor to serve multiple bands, reducing chip area while maintaining signal quality through configuration switching rather than physical component multiplication
2Area of stationary object
If inductors are reused across frequency bands, then chip area is reduced, but signal quality degrades due to spurs and impedance mismatches
Solution Approach 1:
The patent employs dynamic reconfiguration of the LNA circuit between common source and common gate modes using switching mechanisms. This dynamic adaptation allows the same physical inductors to be optimally utilized for different frequency bands, maintaining signal quality by adjusting the circuit topology to match the operating band rather than relying on fixed, band-specific designs
Solution Approach 2:
The patent changes operational parameters (transistor configuration, switching states) to enable the same inductors to function effectively across different frequency bands. By modifying the circuit's operational state rather than its physical composition, the design maintains signal integrity while achieving inductor reuse and area reduction
3Adaptability or versatility
If switches are used to tune out inductors for band switching, then frequency selectivity is improved, but noise figure degrades due to switch on-resistance and parasitic capacitance
Solution Approach 1:
The patent uses dynamic switching between common source and common gate configurations to achieve frequency selectivity for different bands. The switching mechanism enables band selection while the patent addresses noise figure degradation through careful switch placement and configuration design, maintaining lower noise performance compared to static inductor tuning approaches
Data Source
AI summary
Described herein are multi-band LNAs that reuse inductors for different frequency bands to minimize chip area. In an embodiment, a multi-band LNA is capable of operating in a narrowband (NB) and a wideband (WB) while reusing at least one input impedance matching inductor and at least one load inductor for both bands. The reuse of inductors results in a more efficient use of chip area. In an exemplary embodiment, the LNA comprises a common source transistor and a common gate transistor. In this embodiment, the LNA operates in a common source configuration using the common source transistor to amplify input signals in the NB, and operates in a common gate configuration using the common gate transistor to amplify input signals in the WB. The LNA reuses an input impedance matching inductor and a load inductor in both configurations, and thus both bands.