Receiver Filter Equalization for Gain Ripple and Group Delay
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Solution Overview
Problem
Existing receiving circuits in communication systems face challenges in compensating for the varying gain ripple and group delay characteristics of filters across different frequencies, which can lead to signal distortion and require expensive, complex filter designs with increased power consumption.
Innovation Solution
Incorporating an IQ mixer, test signal generator, and filter compensation circuit that applies a test signal to determine equalizer coefficients to compensate for gain ripple and group delay characteristics of filters, using these coefficients to adjust the filter's performance during normal operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a filter is designed to meet required characteristics across a range of frequencies, then filter performance is improved, but device complexity and cost increase
Solution Approach 1:
An equalizer is introduced as an intermediary component to compensate for filter characteristics. The equalizer receives the output signal from the filter and applies corrective filtering to cancel out the filter's frequency-dependent gain variations and group delay effects, thereby achieving flat frequency response without requiring the main filter to be perfectly designed across all frequencies.
Solution Approach 2:
The equalizer dynamically adjusts its transfer function parameters based on the measured or predetermined characteristics of the filter. By changing the equalizer's filtering parameters (coefficients, cutoff frequencies, gain values) to match the inverse of the filter's characteristics, the system achieves compensation across the frequency range without requiring the filter itself to be redesigned.
2Reliability
If a filter is designed to meet required characteristics across a range of frequencies, then filter performance is improved, but manufacturing cost increases
Solution Approach 1:
The equalizer serves as a cost-effective intermediary that provides electronic compensation instead of requiring expensive precision-filter components. By using standard filter components combined with an equalizer circuit, the system achieves the same performance at lower manufacturing cost compared to using a single high-precision filter designed to meet all specifications.
Solution Approach 2:
The frequency compensation function is segmented into two parts: the main filter handles the primary filtering function with relaxed specifications, while the equalizer handles the frequency-dependent compensation. This segmentation allows each component to be manufactured to lower precision standards, reducing overall manufacturing cost while maintaining system performance.
3Reliability
If a filter is designed to meet required characteristics across a range of frequencies, then filter performance is improved, but power consumption increases
Solution Approach 1:
The power consumption is segmented and distributed: the main filter operates with lower power consumption due to relaxed specifications, while the equalizer consumes additional power to provide frequency-dependent compensation. This segmentation allows the system to achieve overall performance goals with more efficient power distribution compared to running a single high-performance filter at maximum power across all frequencies.
Data Source
AI summary
Embodiments of methods and apparatuses can compensate gain ripple and/or group delay characteristics of at least one filter, a receiving circuit embodying a filter, or a communication system having a wireless terminal embodying the receiving circuit.