Programmable RF Notch Filter With Negative Resistance Calibration
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Solution Overview
Problem
Current notch filters in transceivers suffer from reduced sensitivity due to spurious out-of-band signals and limited frequency calibration accuracy, leading to high energy consumption and the need for external, expensive filters to mitigate signal leakage.
Innovation Solution
A programmable notch filter with variable capacitive means and a negative resistance circuit, integrated into a transceiver chip, which includes a control device for digital regulation and self-oscillation calibration to improve frequency accuracy and reduce energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If high-selectivity radio-frequency filters are used to attenuate transmitted signal leakage, then signal rejection is improved, but the filters cannot be integrated into the transceiver chip and require external placement which increases cost and energy consumption
Solution Approach 1:
The patent combines multiple filter functions (notch filter, image rejection filter, and leakage attenuation filter) into a single integrated circuit block that can be implemented on the transceiver chip. This merging of functions eliminates the need for external high-selectivity filters while maintaining signal rejection performance, directly resolving the contradiction between signal rejection and integration capability
Solution Approach 2:
The integrated filter circuit performs multiple functions simultaneously: it acts as a notch filter for transmitted signal leakage, an image rejection filter for superheterodyne receivers, and a general RF filter for spurious signal attenuation. This multi-functionality allows a single integrated circuit to replace multiple external filters, reducing both cost and energy consumption while maintaining comprehensive signal rejection
2Use of energy by stationary object
If external high-selectivity filters are used to reduce transmitted signal leakage, then energy consumption is reduced, but the filters must be placed outside the chip which increases cost
Solution Approach 1:
The patent integrates the filter circuit directly into the transceiver chip, combining what would otherwise require separate external filter components into a single monolithic integrated circuit. This integration eliminates the need for external filters, reducing both manufacturing cost (by eliminating additional components and assembly steps) and energy consumption (by reducing signal path length and component count)
3Measurement precision
If notch filters with programmable band are used to reject image signals and transmitted signal leakage, then frequency calibration accuracy is improved, but noise during signal reception increases
Solution Approach 1:
The patent implements a dynamically adjustable filter circuit where the notch frequency and Q-factor can be programmatically controlled based on the operating conditions. This dynamic adjustment allows the filter to maintain high frequency calibration accuracy across different channels while optimizing the noise floor by adapting the filter bandwidth and depth to match the specific signal characteristics, thereby reducing unnecessary noise amplification that occurs with fixed programmable filters
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enhances the accuracy and reduces energy consumption of notch filters, allowing for better signal rejection and integration within the transceiver chip, while maintaining flexibility for adapting to varying signals.
Implementation Method 1
The inductor and first and second capacitive means are arranged to produce a resonator
Implementation Method 2
a negative resistance circuit suitable for compensating the resistive losses of said at least one inductor
Data Source
AI summary
A notch filter suitable for attenuating certain frequencies of a radio-frequency signal includes an input for receiving the radio-frequency signal and an output for the output of a portion of the radio-frequency signal, first and second capacitive means, at least one inductor and a negative resistance circuit suitable for compensating the resistive losses of said at least one inductor. The inductor and the first and second capacitive means are placed to produce a resonator and the filter comprises a control device suitable for controlling the negative resistance circuit. The input impedance of the filter comprises a pole and a zero, with the pole depending on the second capacitive means and the zero depending on both the first and second capacitive means. The first and second capacitive means are variable and the control device is suitable for controlling the first and second capacitive means.