Punctured Quantizer ADC for Low-Power Wide Dynamic Range
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Solution Overview
Problem
Conventional analog-to-digital converters (ADCs) in battery-operated IoT devices consume high power due to the need for complex circuitry to achieve high signal-to-noise and distortion ratio (SNDR), especially at maximum input signal levels, which is not efficient for devices that spend most of their time in a deep sleep state.
Innovation Solution
A non-linear sigma-delta ADC with a punctured quantizer that intentionally limits SNDR to a fixed saturation level, using a punctured quantizer with non-linear levels and feedback circuitry to reduce power consumption by simplifying the system and controlling quantization error, allowing for a wide dynamic range while maintaining low power usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional ADC design is used to achieve high SNDR at maximum input signal, then signal to noise and distortion ratio is improved, but power consumption increases
Solution Approach 1:
The patent applies parameter changes by implementing a non-linear quantizer with non-uniform quantization levels. The quantization step size varies with input signal amplitude - smaller steps for low-amplitude signals and larger steps for high-amplitude signals. This non-linear parameter transformation allows the ADC to achieve acceptable SNDR across a wide dynamic range without requiring the high precision circuitry needed for uniform fine quantization across all levels, thereby reducing power consumption.
Solution Approach 2:
The patent applies partial action by intentionally limiting the SNDR to a fixed saturation level rather than continuously increasing it with input amplitude. The quantizer provides sufficient precision for low-level signals but accepts higher quantization error for high-level signals. This partial precision approach maintains adequate performance for the application while avoiding the excessive power consumption that would result from providing uniform high precision across the entire dynamic range.
2Adaptability or versatility
If conventional ADC design is used to achieve wide dynamic range, then measurement capability is improved, but device complexity increases
Solution Approach 1:
The patent uses parameter changes through non-linear quantization levels that adapt to input signal amplitude. The quantizer employs fewer levels for high-amplitude signals and more effective resolution for low-amplitude signals. This parameter transformation allows a single quantizer structure to handle a wide dynamic range without requiring multiple precision stages or complex switching circuitry that would increase device complexity.
Solution Approach 2:
The patent applies dynamics by making the quantization characteristics adaptive to the input signal level. The non-linear quantizer automatically adjusts its effective resolution based on the amplitude of the incoming signal, providing fine quantization for small signals and coarse quantization for large signals. This dynamic adaptation enables wide dynamic range coverage with a relatively simple fixed structure, avoiding the complexity of programmable or reconfigurable quantizers.
Data Source
AI summary
In one embodiment, an analog-to-digital converter includes: a sum circuit to receive an analog input signal and a feedback reference signal and generate a sum signal; a feedback circuit coupled to the sum circuit to provide the feedback reference signal to the sum circuit; a filter coupled to the sum circuit to receive the sum signal and generate a filtered signal; and a punctured quantizer coupled to the filter to receive the filtered signal and quantize the filtered signal to a digital output and to output the digital output and to provide the digital output to the feedback circuit.