Receiver DC Offset Calibration Using Digital Feedback Loops
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Solution Overview
Problem
High-speed receiver circuits face degraded transmission performance due to DC offset errors and process deviations, which existing methods attempt to address through increased element area or auxiliary analog circuits, but these solutions impact operating speed and require additional circuitry, such as low-pass filters, further affecting performance.
Innovation Solution
A DC offset calibration system and method that includes a matching circuit, equalizing circuit, amplification circuit, control circuit, and digital-to-analog conversion circuits, operating in multiple modes to adjust digital signals and generate calibration signals to reduce DC offset without occupying additional element area, thereby maintaining high-speed operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the element area is increased to reduce offset error, then the offset error is reduced, but the operating speed of the high-speed receiver circuit is affected
Solution Approach 1:
The patent changes the parameter of offset calibration from physical element area adjustment to digital signal adjustment. The digital-to-analog conversion circuits generate calibration signals with adjustable amplitudes and phases, allowing precise offset compensation without changing the physical size of circuit elements, thereby maintaining high operating speed while reducing offset error.
2Measurement precision
If an auxiliary analog circuit is added to calibrate offset error, then the offset error is calibrated, but additional circuitry is required which occupies element area and affects operating speed
Solution Approach 1:
The patent replaces the traditional mechanical/analog offset calibration system with a digital signal processing system. Digital-to-analog conversion circuits generate calibration signals that are processed digitally, eliminating the need for complex auxiliary analog circuits such as low-pass filters, thereby reducing device complexity while achieving accurate offset calibration.
Solution Approach 2:
The patent introduces digital-to-analog conversion circuits as intermediary components that bridge the digital control domain and the analog signal domain. These conversion circuits generate calibration signals based on digital control words, enabling precise offset calibration without requiring direct analog circuit modifications, thus simplifying the overall circuit structure.
3Measurement precision
If a low-pass filter circuit is added to obtain DC potential for offset control, then the DC offset is eliminated, but the low-pass filter circuit occupies element area and affects operating speed
Solution Approach 1:
The patent replaces the low-pass filter circuit (analog time-domain filtering) with a digital signal processing approach. Digital-to-analog conversion circuits generate calibration signals that directly compensate for DC offset without requiring analog filtering, thereby eliminating the need for low-pass filter circuits and maintaining high operating speed while achieving effective DC offset elimination.
Data Source
AI summary
A DC offset calibration system and method. The method includes: in a first calibration mode, outputting a first digital signal by using a control circuit, generating a first differential calibration signal according to the first digital signal by using a first digital-to-analog conversion circuit, generating a first amplified signal according to the first differential calibration signal by using an amplification circuit, and feeding back the first amplified signal to the control circuit to adjust the first digital signal; and in a second calibration mode, outputting a second digital signal by using the control circuit, generating a second differential calibration signal according to the second digital signal by using a second digital-to-analog conversion circuit, generating a second amplified signal according to the second digital signal by using an equalizing circuit and the amplification circuit, and feeding back the second amplified signal to the control circuit to adjust the second digital signal.