Capacitive Amplifier Output Clipping for Low-Voltage ADC Interface
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Semiconductor devices used in imaging devices face challenges in reducing power consumption while maintaining dynamic range, particularly due to the need for high power source voltage in pixel and amplification circuits and low power source voltage in A/D conversion circuits, leading to inefficiencies and increased power consumption.
Innovation Solution
The semiconductor device incorporates an amplification circuit with a sampling capacitor and feedback capacitor, an operational amplifier circuit, and a clipping circuit to limit output signal voltage, allowing for efficient signal amplification and conversion without the need for a level shift circuit, thereby optimizing power usage and dynamic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the pixel or amplification circuit operates at a high power source voltage to secure dynamic range, then the dynamic range is improved, but the power consumption increases
Solution Approach 1:
The patent divides the semiconductor device into two distinct voltage domains: a high-voltage domain for the pixel array and amplification circuits, and a low-voltage domain for the A/D conversion circuit. This segmentation allows each circuit block to operate at its optimal voltage level, maintaining dynamic range in the pixel/amplification section while reducing power consumption in the A/D conversion section.
Solution Approach 2:
The patent introduces a level shift circuit as an intermediary component between the high-voltage amplification circuit and the low-voltage A/D conversion circuit. This level shift circuit translates the high-voltage output signal to a low-voltage signal level, enabling the A/D conversion circuit to process signals from the high-voltage domain without requiring high operating voltage, thus reducing overall power consumption.
2Adaptability or versatility
If a level shift circuit is added to convert signal levels between high and low voltage systems, then signal compatibility is improved, but the device complexity increases
Solution Approach 1:
The patent integrates the level shift function directly into the output stage of the amplification circuit by sharing capacitive elements (sampling capacitor and feedback capacitor) between the amplification function and the level shifting function. This merging eliminates the need for separate level shift circuitry, reducing device complexity while maintaining signal compatibility between high and low voltage domains.
3Use of energy by moving object
If the A/D conversion circuit operates at a low power source voltage to reduce power consumption, then power consumption is reduced, but the signal level compatibility with high voltage amplification circuit becomes problematic
Solution Approach 1:
The level shift circuit acts as an intermediary that translates the high-voltage output from the amplification circuit to a low-voltage signal level suitable for the A/D conversion circuit. This intermediary component enables the A/D conversion circuit to operate at low voltage for reduced power consumption while maintaining compatibility with the high-voltage amplification circuit through voltage level translation.
Solution Approach 2:
The patent utilizes parameter changes in the capacitive elements (sampling capacitor and feedback capacitor) to achieve both signal amplification and voltage level shifting. By appropriately selecting and configuring these capacitive parameters, the circuit transforms the high-voltage input signal into a low-voltage output signal that is compatible with the low-voltage A/D conversion circuit.
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 reduces power consumption by allowing the A/D conversion circuit to operate at a lower power source voltage, enhances frequency properties, and eliminates the need for a level shift circuit, thereby improving performance and reducing mounting area requirements.
Implementation Method 1
The sampling capacitor holds the input signal on which the sampling is performed, as a signal whose reference is a first reference voltage. The signal that is held in the sampling capacitor is transferred to the feedback capacitor.
Implementation Method 2
The operational amplifier circuit amplifies the signal that is held in the sampling capacitor, according to a ratio between values of the sampling capacitor and the feedback capacitor, and outputs the amplified signal, as a signal whose reference is a second reference voltage.
Implementation Method 3
The overcurrent detection circuit detects an overcurrent that occurs in a case where the voltage of the output signal of the operational amplifier circuit exceeds the second power source voltage that is supplied to the downstream circuit. The overcurrent absorption circuit absorbs the overcurrent.
Data Source
AI summary
A semiconductor device is provided that includes an amplification circuit, a downstream circuit, and a clipping circuit. The amplification circuit includes a sampling capacitor, a feedback capacitor, and an operational amplifier circuit. The sampling capacitor holds air input signal on which sampling is performed, as a signal whose reference is a first reference voltage. The signal that is held in the sampling capacitor is transferred to the feedback capacitor. The operational amplifier circuit amplifies the signal that is held in the sampling capacitor, according to a ratio between values of the sampling capacitor and the feedback capacitor, and outputs the amplified signal, as a signal whose reference is a second reference voltage. The clipping circuit limits a voltage of an output signal of the operational amplifier circuit to a predetermined voltage or below.