Switched Capacitor Sampling With Balanced Reference Voltage Shift
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Solution Overview
Problem
Switched capacitor circuits face challenges in maintaining predictable reference voltage levels, affecting linearity and accuracy, especially when dealing with varying input levels, which can lead to unpredictable operation and increased power consumption.
Innovation Solution
The implementation of a switched capacitor circuit configuration that includes main and replica sampler circuits, along with an amplifier, where the main sampler circuit stores charges based on a reference voltage and the replica sampler circuit holds charges using a different reference voltage, ensuring a balanced charge supply regardless of input levels, and the use of charge supply circuits to provide additional charges efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional switched capacitor circuit uses a single reference voltage for sampling, then the circuit structure is simple, but the linearity and accuracy deteriorate when input levels vary
Solution Approach 1:
The switched capacitor circuit is divided into multiple independent sampling paths: a first sampling path for positive input signals and a second sampling path for negative input signals. Each path has its own sampling capacitor and reference voltage source. This segmentation allows each path to be optimized independently, improving linearity and accuracy without requiring complex overall restructuring.
Solution Approach 2:
Different reference voltages are applied to different sampling paths based on local requirements. The first sampling path uses a first reference voltage optimized for positive signals, while the second sampling path uses a second reference voltage optimized for negative signals. This local optimization ensures accurate sampling across the full input range without compromising circuit simplicity.
2Adaptability or versatility
If the reference voltage level varies with input level, then the circuit can adapt to different signals, but the operation becomes unpredictable and power consumption increases
Solution Approach 1:
Reference voltages are pre-established and stored in dedicated reference voltage sources before sampling occurs. These reference voltages are selected based on the expected signal polarity (positive or negative) and are made available in advance to the sampling capacitors. This preliminary preparation ensures predictable operation while maintaining adaptability to different signal levels.
Solution Approach 2:
Dedicated reference voltage sources act as intermediaries between the power supply and the sampling capacitors. These intermediary components buffer and stabilize the reference voltages, isolating the sampling operation from power supply variations and ensuring predictable, stable operation across different input conditions.
3Manufacturing precision
If additional charge supply circuits are added to maintain even charge distribution, then linearity improves, but circuit area increases
Solution Approach 1:
The charge supply function is merged with the existing reference voltage sources. The same reference voltage sources that provide voltage references also supply the necessary charges to the sampling capacitors during the sampling phase. This merging eliminates the need for separate charge supply circuits, maintaining linearity while avoiding additional circuit area.
Solution Approach 2:
The reference voltage sources are designed to perform multiple functions: providing voltage references for sampling and simultaneously supplying charges to maintain even charge distribution in the sampling capacitors. This multi-functionality achieves the linearity improvement without adding dedicated charge supply circuits, thus avoiding increased circuit area.
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
This configuration improves the linearity and accuracy of the switched capacitor circuit operations, reduces power consumption, and allows for faster operation while maintaining low costs on a small circuit area.
Implementation Method 1
a first capacitive element for storing charges corresponding to one input of a differential input
Implementation Method 2
a first sampling switch element for transferring the one input to the first capacitive element
Implementation Method 3
a first holding switch element for providing a first reference voltage to the first capacitive element
Data Source
AI summary
A switched capacitor circuit includes a first main sampler circuit, a second main sampler circuit, a first replica sampler circuit, and a second replica sampler circuit. The first main sampler circuit samples a first input of a differential input, and generates a first output corresponding to the sampled first input based on a first reference voltage. The second main sampler circuit samples a second input of the differential input, and generates a second output corresponding to the sampled second input based on a second reference voltage. The first replica sampler circuit receives the first input, and holds the received first input based on the second reference voltage. The second replica sampler circuit receives the second input, and holds the received second input based on the first reference voltage.