Filter Circuit Calibration via Gain Feedback for Time Constant Drift
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Solution Overview
Problem
Conventional calibration methods for filter circuits in wireless communication systems can only compensate for manufacturing process variations in capacitors and resistors, failing to address deviations in other components like operation amplifiers, which affect signal quality due to frequency response deviations from designed values.
Innovation Solution
A calibration device and method that includes a signal generator and processor to provide an input signal to a filter circuit, calculate and compare the real gain with a target gain, and adjust the filter circuit's time constant to align with the originally designed values, effectively compensating for deviations in all components, including operation amplifiers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional calibration method adjusting only capacitor or resistor is used, then the time constant can be compensated for capacitor/resistor deviation, but other components (e.g. operation amplifier) cannot be compensated for manufacturing process variation
Solution Approach 1:
The patent changes the calibration approach from adjusting only capacitor/resistor values to adjusting the operating frequency parameter of the filter circuit. By measuring the actual center frequency and adjusting the operating frequency accordingly, the system compensates for manufacturing variations in all components including operation amplifiers, not just capacitors and resistors.
2Device complexity
If the filter circuit uses fixed designed values, then the circuit design is simple, but the frequency response deviates from designed values due to manufacturing process variation
Solution Approach 1:
The patent implements a feedback mechanism where the actual center frequency of the filter circuit is measured and used to adjust the operating frequency. This closed-loop feedback approach maintains simple circuit design while compensating for manufacturing variations to achieve accurate frequency response.
3Device complexity
If calibration adjusts only capacitor value, then the calibration circuit is simple with same time constant, but cannot compensate for deviations in other components like operation amplifier
Solution Approach 1:
The patent replaces the conventional mechanical/electrical adjustment of capacitor values with a frequency-domain approach. Instead of physically adjusting component values, the system measures frequency response characteristics and adjusts the operating frequency parameter, achieving more comprehensive compensation with similar circuit complexity.
Data Source
AI summary
A calibration device includes a signal generator and a processor. The signal generator is configured to provide an input signal to a filter circuit, wherein the filter circuit has a real time constant and is configured to receive the input signal to output an output signal. The processor is configured to calculate a real gain according to the output signal and the input signal, compare the real gain with a target gain to obtain a comparison result and determine whether to adjust the real time constant of the filter circuit according to the comparison result. The present disclosure also provides a calibration method.