RF Feedback LNA Receiver for Mixer-Free RF-to-Digital Conversion
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Solution Overview
Problem
Low-power wireless receivers face challenges in reducing current consumption while maintaining linearity and blocking performance, as existing designs like super-regenerative receivers have poor performance in these areas, and reducing analog stages does not fully address the issue.
Innovation Solution
A mixer-free RF analog-to-digital converter that directly converts RF input to a digital output using a single-bit or multi-bit quantizer with a low-noise feedback loop, eliminating the need for analog baseband stages and providing a low-noise feedback signal to a noise shaping loop filter, which can be enhanced with multiple poles and zeros, and cascaded LNAs for higher order sigma-delta modulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If regenerative receiver or super-regenerative receiver designs are used to reduce current consumption, then power consumption is reduced, but linearity and blocking performance deteriorate
Solution Approach 1:
The patent replaces traditional analog regenerative receiver mechanisms with a digital direct RF-to-digital conversion system. The RF signal is directly converted to digital domain using a quantizer, eliminating the need for analog regeneration stages that cause poor linearity and blocking performance while maintaining low power consumption.
Solution Approach 2:
The patent changes the operating parameters by operating the LNA in a high-gain, high-impedance mode with feedback, enabling the system to achieve both low power consumption and good linearity. The feedback mechanism adjusts the effective impedance and gain to optimize performance.
2Use of energy by moving object
If the number of analog stages is reduced to make the receiver more digital, then power consumption is reduced, but noise figure performance may deteriorate
Solution Approach 1:
The patent implements a feedback path from the quantizer output back to the LNA input. This feedback mechanism shapes the noise spectrum and allows the system to achieve low noise figure performance despite having fewer analog stages. The feedback loop filter selectively attenuates out-of-band noise while preserving in-band signal quality.
Solution Approach 2:
The patent introduces an RF feedback engine as an intermediary component that bridges the digital quantizer output and the analog LNA input. This intermediary converts digital feedback signals to analog form and applies them to the LNA, enabling noise shaping and optimization without requiring multiple analog stages.
3Object-affected harmful factors
If a feedback path is added to provide low-noise feedback signal, then noise figure is improved, but device complexity increases
Solution Approach 1:
The patent designs the feedback path to serve multiple functions simultaneously: it provides noise shaping, implements loop filtering, and enables digital control of the LNA characteristics. The RF feedback engine performs both digital-to-analog conversion and feedback signal generation, reducing the need for separate dedicated circuits.
Solution Approach 2:
The patent combines the LNA and quantizer into a tightly coupled system where the feedback path integrates both analog and digital domains. The RF feedback engine merges the digital feedback control with the analog LNA operation, creating a unified system that achieves low noise figure without requiring separate complex noise control circuits.
Data Source
AI summary
Methods and apparatus to perform radio frequency (RF) analog-to-digital conversion are described. According to one example, a receiver includes an amplifier to amplify received analog RF signals and a mixer-free circuit for converting the received analog RF signals to digital signals.