Wideband LNA Circuit Using N-Path Filtering for Blocker Rejection
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Solution Overview
Problem
Current LNAs have limited bandwidth, linearity, and selectivity, leading to increased cost and complexity when extending radio architectures to multiple transceivers with off-chip components, and existing solutions suffer from noise and compression issues.
Innovation Solution
Implementing an LNA circuitry with a voltage ladder and N-path filter circuitry, including a staggered input to unit cells and differential cascode stages, to achieve wideband operation and attenuate blockers while maintaining low noise and selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional radio architecture is extended to multiple transceivers with off-chip components, then multiple frequency bands can be supported, but cost and complexity increase prohibitively
Solution Approach 1:
The patent combines multiple transceiver functions into a single integrated transceiver that can simultaneously operate on multiple frequency bands. The shared components include voltage ladder circuitry, N-path filter bank, and cascode stages that serve multiple frequency bands, eliminating the need for separate transceivers and off-chip components for each band.
Solution Approach 2:
The patent creates universal circuit blocks that can operate across multiple frequency bands. The voltage ladder, N-path filter bank, and cascode stages are designed as multi-functional components that can be configured for different frequency bands through clock signal control, allowing a single transceiver to perform multiple frequency band operations.
2Device complexity
If conventional LNA designs are used, then circuit simplicity is maintained, but bandwidth, linearity, and selectivity are limited
Solution Approach 1:
The LNA is divided into distinct functional segments: voltage ladder circuitry for signal distribution, N-path filter bank for frequency-selective filtering, and cascode stages for amplification. Each segment performs a specific function that contributes to the overall wideband operation and selectivity while maintaining modular simplicity.
Solution Approach 2:
The patent introduces dynamic elements including clock signals that control the N-path filter bank switching, voltage ladder configuration, and cascode stage operation. These dynamic components enable the LNA to adapt its characteristics across different frequency bands and maintain optimal performance throughout the wide bandwidth.
3Adaptability or versatility
If LNA operates across wide bandwidth, then multi-frequency support is achieved, but noise and compression issues increase
Solution Approach 1:
The N-path filter bank acts as an intermediary between the voltage ladder input stage and the cascode amplification stage. It provides frequency-selective filtering that attenuates out-of-band blockers and noise before they reach the amplification stage, preventing compression while maintaining wideband operation capability.
Solution Approach 2:
The patent employs feedback mechanisms in the cascode stages and voltage ladder configuration to maintain linearity and reduce noise across the wide bandwidth. The feedback paths help stabilize the operating point and compensate for variations in different frequency bands, reducing compression effects and noise figure degradation.
Data Source
AI summary
Embodiments may comprise low noise amplifier (LNA) circuitry with a tunable wideband and high linearity. Embodiments may increase the linearity of the LNA circuitry and reduce noise. The LNA circuitry may comprise an inverter having a differential input coupled with the antenna, a first cascode circuitry coupled between a differential output of the inverter and a second cascode stage circuitry, wherein the second cascode stage circuitry comprises a first N-path filter circuitry coupled with a first set of outputs of clock circuitry having a clock frequency of an incoming signal minus a delta frequency and a second N-path filter circuitry coupled with a second set of outputs of clock circuitry having a clock frequency of an incoming signal plus a delta frequency. Combining the response of the two N-path filter circuitries at plus and minus delta frequency may achieve frequency selectivity and attenuate blockers.