Signal Receiver Calibration for ADC DC Offset Compensation
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Solution Overview
Problem
Wireless devices face issues with DC offset errors in signal receiving circuits due to unwanted direct current offsets in analog-to-digital converters (ADCs) and other components, leading to decreased linearity.
Innovation Solution
A signal receiving circuit with an RF front-end, filter, amplifier, ADC, compensation, and control circuits, along with a calibration method that generates compensation codes to adjust amplifier gains and compensate for DC offsets, using look-up tables and high-pass filters to improve linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If DC offset compensation is not implemented, then the circuit structure remains simple, but the linearity of the ADC decreases due to errors
Solution Approach 1:
The patent applies preliminary action by performing DC offset compensation before the ADC conversion process. The compensation circuit pre-adjusts the amplified signal by subtracting the DC offset component, ensuring that the signal entering the ADC is already corrected. This preliminary compensation prevents linearity degradation at the source rather than correcting it afterward, thereby improving manufacturing precision while keeping the overall structure manageable.
Solution Approach 2:
The patent introduces a compensation circuit as an intermediary component between the amplifier and the ADC. This intermediary circuit generates a compensation signal that counteracts the DC offset, mediating the interaction between the amplified signal and the ADC. By inserting this intermediate compensation stage, the system achieves better linearity without directly modifying the core ADC structure, thus balancing precision improvement with structural complexity.
2Measurement precision
If DC offset compensation is not implemented, then the device complexity remains low, but signal conversion accuracy decreases
Solution Approach 1:
The compensation circuit performs preliminary correction of the DC offset before the signal enters the ADC for conversion. By pre-subtracting the offset component from the amplified signal, the system ensures that the conversion process operates on already-corrected data, thereby improving measurement precision without requiring complex post-processing or redundant conversion stages.
Solution Approach 2:
The patent implements a feedback mechanism where the compensation circuit continuously monitors and adjusts the DC offset compensation based on the amplified signal characteristics. The compensation signal is dynamically generated and fed back into the signal path, creating a closed-loop system that maintains high conversion accuracy. This feedback approach improves measurement precision while keeping the device structure relatively compact compared to open-loop correction methods.
Data Source
AI summary
A signal receiving circuit receives an input signal and includes a radio frequency (RF) front-end circuit, a filter circuit, an amplifier circuit, an analog-to-digital converter (ADC), a compensation circuit, an adder circuit, and a control circuit. The RF front-end circuit down-converts the input signal to generate a down-converted signal. The filter circuit filters the down-converted signal to generate a filtered signal. The amplifier circuit amplifies, according to a control signal, the filtered signal with a gain to generate an amplified signal. The ADC converts the amplified signal into a first digital code. The compensation circuit generates a compensation code according to at least one of the control signal and the gain. The adder circuit generates a second digital code according to the compensation code and the first digital code. The control circuit generates the control signal according to the second digital code.