Bandpass Filter Feedback Layout for Clock Leakage Isolation
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Solution Overview
Problem
The existing bandpass filters with impedance frequency conversion circuits placed prior to amplifier circuits suffer from clock signal leakage to the input side and impaired flatness within the passband, especially when multiple stages are connected, and struggle to effectively attenuate out-of-band signals when a wide signal band is required.
Innovation Solution
A bandpass filter configuration that includes an amplifier, an impedance frequency conversion circuit connected between the amplifier's output and ground, and a feedback circuit between the amplifier's input and output, which prevents clock leakage and provides excellent out-of-passband signal attenuation by changing impedance based on signal frequency and using feedback to optimize impedance matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an impedance frequency conversion circuit is placed prior to the amplifier circuit, then out-of-band signal attenuation is improved, but clock signal leakage to the input side occurs
Solution Approach 1:
The patent extracts the impedance frequency conversion circuit from the input side and relocates it to the output side of the amplifier circuit. This separation removes the source of clock signal leakage from the input path while preserving the out-of-band attenuation function at the output, thereby resolving the contradiction between signal attenuation and clock leakage.
Solution Approach 2:
Instead of placing the impedance frequency conversion circuit before the amplifier as in conventional designs, the patent inverts the arrangement by positioning it after the amplifier. This inversion allows the circuit to perform impedance conversion for out-of-band signals without introducing clock leakage to the input, effectively solving the technical contradiction.
2Object-affected harmful factors
If multiple stages are connected to increase out-of-band attenuation, then signal attenuation is improved, but flatness within the passband is impaired
Solution Approach 1:
The patent introduces a feedback circuit that connects the output of the amplifier back to its input. This feedback mechanism compensates for variations in the passband response caused by multiple impedance conversion stages, thereby maintaining passband flatness while achieving high out-of-band attenuation through cascaded stages.
3Adaptability or versatility
If the filter passband is set wide to accommodate a wide signal band, then signal band coverage is improved, but out-of-band signal attenuation is reduced
Solution Approach 1:
The patent employs dynamically controllable impedance conversion circuits that can adjust their characteristics based on the desired passband width. By making the impedance conversion dynamic rather than fixed, the system can accommodate wide signal bands while maintaining effective out-of-band attenuation through adaptive tuning of the conversion parameters.
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
This configuration effectively prevents clock leakage and achieves superior out-of-passband signal attenuation while maintaining flatness within the passband, allowing for adjustable passband width and improved signal handling capabilities.
Implementation Method 1
an impedance frequency conversion circuit that is connected between an output of the amplifier and ground and changes impedance depending on whether or not a frequency of a signal output from the amplifier is within a predetermined passband
Implementation Method 2
a feedback circuit connected between the output and an input of the amplifier
Data Source
AI summary
A bandpass filter is provided that prevents clock leakage to the input side of an amplifier circuit and has excellent out-of-passband signal attenuation. It includes an amplifier (102) connected between an input terminal and an output terminal, an impedance frequency conversion circuit (101) that is connected between an output of the amplifier and ground and changes impedance depending on whether or not the frequency of a signal output from the amplifier is within a predetermine passband, and a feedback circuit (103) connected between the output and an input of the amplifier.