ADC Supply-Voltage Reference Scheme for Stable Low-Power Conversion
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Solution Overview
Problem
Existing analog-to-digital converters (ADCs) face challenges with noise, power consumption, and area occupancy due to large capacitors and reference voltage buffering, especially when increasing quantization bits or scaling outputs, which affects conversion speed and resolution.
Innovation Solution
The use of power-supply voltages as reference voltages allows for increased quantization bits and scaling of outputs without the need for buffer circuits and large capacitors, reducing noise and power consumption while improving conversion speed and resolution by specifying a full-scale range with a positive and negative power-supply voltage or ground.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large bypass capacitors are used to stabilize reference voltages and reduce noise, then noise is reduced and stability is improved, but area occupancy increases and power consumption increases
Solution Approach 1:
The patent extracts and eliminates the large bypass capacitors from the reference voltage stabilization circuit. Instead of using capacitive filtering, the invention uses the power supply voltages themselves as reference voltages, removing the need for large energy-storing components while maintaining stability through direct power supply coupling.
Solution Approach 2:
The power supply voltages serve dual functions: they provide power to the ADC circuitry and simultaneously serve as the reference voltages for conversion. This multi-functionality eliminates the need for separate reference voltage generation and stabilization circuits, reducing area and power consumption.
2Reliability
If buffer circuits are used to stabilize reference voltages, then noise is reduced and stability is improved, but power consumption increases and device complexity increases
Solution Approach 1:
The patent removes buffer circuits from the reference voltage path. By using power supply voltages directly as reference voltages, the invention eliminates the need for active buffering stages that consume power and add complexity, while maintaining voltage stability through the inherent rigidity of power supply rails.
Solution Approach 2:
The power supply system serves itself by providing both power and reference voltage functions. The power supply voltages automatically serve as stable references without requiring external stabilization circuits, as the same power rails that supply operating voltage inherently provide the reference levels needed for ADC conversion.
3Measurement precision
If the number of quantization bits is increased to improve resolution, then measurement precision is improved, but conversion speed decreases due to settling time requirements
Solution Approach 1:
The patent changes the reference voltage parameter from traditional stable reference voltages to power supply voltages. This parameter change reduces the settling time requirement because power supply voltages have inherently low impedance and fast response characteristics, enabling higher conversion speeds even with increased quantization bits.
4Object-affected harmful factors
If reference voltage buffering and stabilization circuits are used, then noise is reduced, but power consumption increases and device complexity increases
Solution Approach 1:
The patent extracts and removes the reference voltage buffering and stabilization circuits from the ADC system. By using power supply voltages directly as references, the invention eliminates entire subsystems dedicated to reference voltage management, reducing circuit complexity while maintaining noise performance through the low-impedance power supply rails.
Data Source
AI summary
A conversion circuit that performs analog-to-digital conversion is described. During operation, the conversion circuit receives an input signal. Then, the conversion circuit performs analog-to-digital conversion and provides a quantized output corresponding to the input signal based at least in part on a first power-supply voltage and a second power-supply voltage of the conversion circuit. For example, the quantized output may be based at least in part on a comparison of the input signal to the first power-supply voltage and the second power-supply voltage. Moreover, the first power-supply voltage and the second power-supply voltage may specify a full-scale range of the conversion circuit. When the full-scale range exceeds a second full-scale range associated with reference voltages that are other than the first power-supply voltage and the second power-supply voltage, the quantized output may correspond to a larger number of bits than when the full-scale range equals the second full-scale range.