Current Steering Circuit With Capacitance Matching for Audio Linearity
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Solution Overview
Problem
High fidelity audio systems face signal distortion and noise due to unmatched output capacitance in current steering structures of digital-to-analog converters, leading to decreased linearity of amplified audio signals.
Innovation Solution
The implementation of a current cell structure with two current sources and capacitor compensation devices to equalize the output capacitance, along with a switching mechanism to provide complementary inputs to an amplifier circuit, ensuring balanced capacitance and improved signal linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current sources are used in a current steering structure, then high fidelity audio signal generation is achieved, but output capacitance mismatch causes signal distortion and noise
Solution Approach 1:
The patent changes the capacitance parameter by adding compensation capacitors to adjust the total output capacitance of each current source. By selecting specific capacitance values for the compensation capacitors, the total capacitance of current sources with different transconductance values is equalized, thereby eliminating the harmful effects of capacitance mismatch on signal linearity
Solution Approach 2:
The patent converts the harmful effect of capacitance mismatch into a benefit by deliberately adding compensation capacitors. The harmful parameter (capacitance difference) is transformed into a controllable design parameter, where the compensation capacitors serve to equalize the total capacitance values, turning what was previously a source of distortion into a means of achieving signal linearity
2Adaptability or versatility
If multiple current sources with different transconductance values are used, then improved audio signal processing is achieved, but output capacitance mismatch increases
Solution Approach 1:
The patent changes the capacitance parameter by adding compensation capacitors to adjust the total output capacitance of each current source. By selecting specific capacitance values for the compensation capacitors, the total capacitance of current sources with different transconductance values is equalized, thereby eliminating the harmful effects of capacitance mismatch on signal linearity
Solution Approach 2:
The patent applies local quality by providing individual compensation capacitors to each current source based on its specific transconductance value. Each current source receives a tailored compensation capacitance value that is specific to its characteristics, allowing current sources with different transconductance values to all achieve matched total capacitance values
Data Source
AI summary
Systems and methods are provided for improved linearity of audio amplifiers. In one example, a system includes a first current source configured to provide a first current signal having a first current source output capacitance, and a second current source configured to provide a second current signal having a second current source output capacitance, where the first and second current source output capacitances are a different value. The system further includes a first capacitor compensation device coupled to an output of the first current source configured to provide a capacitance value to compensate for the second current source output capacitance, and a second capacitor compensation device coupled to an output of the second current source configured to provide a capacitance value to compensate for the first current source output capacitance. The system further includes a plurality of switches configured to switch the first and second current signals.