Switched Capacitor ADC Noise Shaping for Higher Signal Purity
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Solution Overview
Problem
Analog-to-digital converters (ADCs) face performance issues due to non-ideal factors such as process variations and quantization noise, which affect their ability to process high-resolution data effectively.
Innovation Solution
A switched capacitor circuit is introduced, comprising a first and second capacitor and a switching circuit that selectively couples these capacitors to an input terminal of a quantizer using clock signals, allowing for noise shaping by stacking the capacitors in series to transmit a combination of signals for improved analog-to-digital conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional ADC architecture is used, then the device structure is simple, but the signal-to-noise ratio is poor due to quantization noise affecting high-resolution data processing
Solution Approach 1:
The switched capacitor circuit is divided into multiple functional units including first and second capacitor arrays, switching circuits for different phases, and a quantizer. This segmentation allows independent optimization of each unit's function while collectively achieving noise shaping to improve signal-to-noise ratio without excessive overall complexity
Solution Approach 2:
The switched capacitor circuit acts as an intermediary between the input signal and the quantizer, performing noise shaping on the residue signal before quantization. This intermediary processing redistributes quantization noise to higher frequency bands, improving the signal-to-noise ratio in the baseband without requiring a fundamentally complex ADC architecture
2Reliability
If the capacitors are stacked in series to provide signal combination, then the noise shaping function is achieved, but the circuit configuration complexity increases
Solution Approach 1:
The switching circuit operates in periodic phases (first phase and second phase) controlled by clock signals. During the first phase, capacitors are connected in a first configuration; during the second phase, they are stacked in series. This periodic switching achieves noise shaping through regular signal combination while maintaining predictable and manageable circuit control
Solution Approach 2:
The circuit transitions between different configurations dynamically based on the conversion phase. The switching circuit reconfigures capacitor connections from parallel/individual storage mode to series stacking mode for signal combination. This dynamic reconfiguration enables the noise shaping function while allowing the circuit to maintain optimal performance across different operational states
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
The noise-shaping function enhances the signal-to-noise ratio of the ADC output, improving the overall performance by redistributing quantization noise to higher frequency bands, thereby increasing the signal quality in lower frequency bands.
Implementation Method 1
The first capacitor is configured to receive a first signal. The second capacitor is configured to receive a second signal.
Implementation Method 2
The switching circuit is configured to selectively couple the first capacitor and the second capacitor to an input terminal of a quantizer according to at least one clock signal.
Data Source
AI summary
A switched capacitor circuit includes a first capacitor, a second capacitor, and a switching circuit. The first capacitor is configured to receive a first signal. The second capacitor is configured to receive a second signal. The switching circuit is configured to selectively couple the first capacitor and the second capacitor to an input terminal of a quantizer according to at least one clock signal. In a first configuration of the switching circuit, the first capacitor is configured to store the first signal, and the second capacitor is configured to store the second signal. In a second configuration of the switching circuit, the first capacitor and the second capacitor are stacked in series, in order to transmit a combination of the first signal and the second signal to the input terminal of the quantizer.