Single-Amplifier Biquad Filter for Constant Group Delay
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Solution Overview
Problem
Conventional reconstruction filters in transmitters face a trade-off between achieving a flat gain response and constant group delay, often resulting in undesirable distortion, and require additional amplifiers to compensate for group delay, which increases power consumption and physical size.
Innovation Solution
A single amplifier biquad filter topology is used to compensate for group delay, providing a flat gain response and constant group delay for passband frequencies, reducing the need for additional amplifiers and minimizing phase distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional second-order filter topologies are implemented to achieve high quality factors for group delay compensation, then group delay compensation is improved, but device complexity and power consumption increase due to requiring multiple amplifiers
Solution Approach 1:
The patent combines the functions of group delay compensation and signal amplification into a single amplifier circuit. The biquad filter topology integrates the negative gain component generation and signal amplification in one amplifier, eliminating the need for separate amplifiers required by conventional Tow-Thomas biquad circuits that use three amplifiers.
Solution Approach 2:
The single amplifier in the biquad filter performs multiple functions simultaneously: it provides signal amplification, generates the negative gain component through its feedback configuration, and implements the filtering function. This multi-functional design reduces component count while maintaining high quality factor for group delay compensation.
2Reliability
If additional amplifiers are used in conventional filter topologies to achieve high quality factors, then group delay manipulation capability is improved, but power consumption increases
Solution Approach 1:
The patent merges the power-consuming amplification function with the group delay manipulation function into a single amplifier circuit. By integrating these functions, the system achieves high quality factor for group delay manipulation while consuming power equivalent to only one amplifier rather than three or more separate amplifiers.
3Reliability
If additional amplifiers are used in conventional filter topologies to achieve high quality factors, then group delay manipulation capability is improved, but physical area increases
Solution Approach 1:
The patent combines multiple amplifier functions into a single amplifier circuit implementation. This integration reduces the physical area occupied by the filter from what would be required for three separate amplifiers (in Tow-Thomas biquad) to just one amplifier, thereby reducing the overall chip area while maintaining high quality factor for group delay manipulation.
Data Source
AI summary
Apparatus and systems are provided for a single amplifier filter capable of a high quality factor. A filter comprises an amplifier having an amplifier input and an amplifier output, wherein the amplifier is configured to produce an output signal at the amplifier output based on a signal at the amplifier input. A first resistive element is coupled between an input node and the amplifier input, a second resistive element is coupled between a first node and the amplifier input, and a third resistive element is coupled between the amplifier output and the first node. A first capacitive element is coupled between the amplifier output and the amplifier input. The filter comprises a second node for an inverse of the output signal, wherein a second capacitive element is coupled between the first node and the second node.