Complex Filter Calibration Using Interlaced Compensation Resistors
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Solution Overview
Problem
Conventional low IF receivers face challenges in eliminating image signal interference due to phase and amplitude mismatches, which are difficult to correct with existing calibration methods that require complex computations and excessive elements, leading to power consumption issues.
Innovation Solution
A complex filter and calibration method utilizing a small number of easily integrated compensation resistors to adjust the ratios of input resistors and compensation resistors, allowing independent elimination of amplitude and phase mismatches between in-phase and quadrature-phase signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional calibration methods are used to eliminate image signal interference, then phase and amplitude mismatches can be corrected, but the system complexity and power consumption increase due to complex computations and excessive elements
Solution Approach 1:
The patent changes the parameters of existing resistors in the complex filter to achieve calibration. By adjusting the resistance values of input resistors and compensation resistors, the system corrects phase and amplitude mismatches without adding complex calibration circuits, thereby reducing device complexity while maintaining image signal elimination capability
Solution Approach 2:
The patent extracts the calibration function from a separate complex calibration system and integrates it into the existing complex filter structure. By utilizing the filter's own resistors for both filtering and calibration purposes, the system eliminates the need for excessive external calibration elements, reducing overall device complexity
2Reliability
If conventional calibration methods are used to eliminate image signal interference, then phase and amplitude mismatches can be corrected, but power consumption increases due to complex computations and excessive elements
Solution Approach 1:
The patent achieves calibration by simply adjusting resistor parameters rather than performing complex computations. This parameter-based approach eliminates the need for intensive digital signal processing during calibration, significantly reducing power consumption while maintaining the ability to correct phase and amplitude mismatches
Solution Approach 2:
The patent removes the power-consuming complex computation and excessive calibration elements from the system by integrating calibration functionality into the existing filter structure. The calibration is achieved passively through resistor parameter adjustments, eliminating the need for additional active calibration circuits that would consume power
3Reliability
If a complex band-pass filter is used to eliminate image signals, then image signal interference is reduced, but the filter structure becomes complicated and difficult to integrate
Solution Approach 1:
The patent makes the resistors in the complex filter serve multiple functions: they simultaneously perform frequency filtering and phase/amplitude calibration. This multi-functionality eliminates the need for separate calibration components, simplifying the overall filter structure and making it easier to integrate into receiver systems
Solution Approach 2:
The patent merges the calibration function with the filtering function by using the same resistors for both purposes. By combining these functions into a single integrated structure rather than using separate components, the filter becomes simpler to manufacture and integrate while maintaining image signal elimination capability
Data Source
AI summary
A complex filter for processing an in-phase signal and a quadrature-phase signal includes a first low-pass filter, a second low-pass filter, a connection unit between the first low-pass filter and the second low-pass filter, a first compensation resistor and a second compensation resistor. The first compensation resistor and the second compensation resistor are interlacedly coupled to input resistors of the first low-pass filter and the second low-pass filter.