LC Resonant Frequency Tuning for Stable RF Receiver Gain
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Solution Overview
Problem
Wireless communication transceivers face challenges in stabilizing the gain of RF circuits, particularly LC circuits, due to variations in temperature, supply voltage, and process variations, which affect signal strength measurement accuracy and device location precision in applications like wireless sensor networks and smart electric grids.
Innovation Solution
The implementation of a circuit configuration that includes an LC circuit, a positive transconductance circuit, and a negative transconductance circuit to adjust conductance between the ends of the LC circuit, stabilizing parasitic resistance and quality factor through temperature detection and RSSI feedback, thereby maintaining consistent gain across variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If LC circuits are used to set voltage gain in RF blocks, then gain can be adjusted, but gain stability deteriorates due to PVT variations
Solution Approach 1:
The patent implements a feedback mechanism where the RSSI measurement is fed back to adjust the LC circuit tuning, creating a closed-loop system that automatically compensates for gain variations due to PVT changes
Solution Approach 2:
The patent dynamically changes the resonant frequency parameter of the LC circuit based on RSSI measurements and temperature detection, allowing the system to adapt to PVT variations while maintaining stable gain
2Adaptability or versatility
If LC circuit resonant frequency varies with PVT variations, then frequency tuning flexibility is improved, but measurement precision deteriorates
Solution Approach 1:
The system uses RSSI feedback to detect frequency deviations caused by PVT variations and automatically retunes the LC circuit to maintain accurate signal strength measurements
Solution Approach 2:
The system performs preliminary frequency tuning based on temperature detection before RSSI measurement, pre-compensating for expected PVT variations to ensure measurement accuracy
3Adaptability or versatility
If quality factor varies with PVT variations, then circuit adaptability is improved, but receiver performance deteriorates
Solution Approach 1:
The patent employs feedback control where RSSI measurements guide quality factor adjustments, enabling the circuit to adapt to PVT variations while maintaining consistent receiver performance
Solution Approach 2:
The system dynamically adjusts the quality factor parameter of the LC circuit based on detected PVT variations and RSSI feedback, optimizing receiver performance across different operating conditions
Data Source
AI summary
Apparatus and methods are disclosed related to tuning a resonant frequency of an LC circuit. In some implementations, the LC circuit can be embodied in a low noise amplifier (LNA) of a receiver. The receiver can include a component configured to generate an indicator of received signal strength indication (RSSI) of a radio frequency (RF) signal received by the receiver. A control block can adjust the resonant frequency of the LC circuit based at least in part on the indicator of RSSI. As another example, the receiver can include an oscillator, such as a VCO, separate from the LC circuit that can be used to tune the resonant frequency of the LC circuit. These apparatus can compensate for variation in a zero imaginary component of an impedance across the LC circuit.