Shared Op-Amp ADC Circuit for Compact Image Sensors

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Solution Overview

Problem

Conventional image sensor systems require separate amplification and analog-to-digital conversion circuits, which occupy significant chip area and consume high power, limiting their performance and image quality.

Innovation Solution

An amplifying/digitizing circuit utilizing a single operational amplifier that can switch between amplification and analog-to-digital conversion modes, incorporating capacitors and switches to manage signal processing, thereby integrating both functions into a compact and power-efficient design.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If separate amplification and ADC circuits are used, then signal amplification and digital conversion functions are achieved, but chip area and power consumption increase

Engineering Contradiction:
Improvesignal processing functionalityVSAvoidchip area
Core Design Contradiction:
Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The patent combines the amplification circuit and ADC circuit into a single integrated circuit block. The amplifier and comparator share common components including capacitors C1-C4, switches SW1-SW6, and power supply connections, eliminating the need for separate discrete amplification and conversion circuits while maintaining both functions

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The integrated circuit performs multiple functions through a single operational amplifier that operates in different modes. The same amplifier circuit provides both signal amplification during the amplification phase and voltage comparison during the ADC phase, controlled by the timing of switch operations and clock signals

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If separate amplification and ADC circuits are used, then signal amplification and digital conversion functions are achieved, but power consumption increases

Engineering Contradiction:
Improvesignal processing functionalityVSAvoidpower consumption
Core Design Contradiction:
Adaptability or versatilityVSUse of energy by stationary object

Solution Approach 1:

The patent combines the amplification circuit and ADC circuit into a single integrated circuit block. The amplifier and comparator share common components including capacitors C1-C4, switches SW1-SW6, and power supply connections, eliminating the need for separate discrete amplification and conversion circuits while maintaining both functions

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The circuit operates in periodic cycles alternating between amplification mode and ADC mode. During each cycle, the amplifier is activated only when needed for signal amplification, then deactivated during the comparison phase, reducing overall power consumption compared to continuously operating separate circuits

Inventive Principle:
Principle #19Periodic action

3Area of stationary object

If a single operational amplifier is used for both amplification and ADC functions, then chip area and power consumption are reduced, but circuit complexity increases

Engineering Contradiction:
Improvechip areaVSAvoidcircuit configuration
Core Design Contradiction:
Area of stationary objectVSDevice complexity

Solution Approach 1:

The circuit operation is segmented into distinct phases controlled by clock signals CLK1 and CLK2. During the first phase (CLK1 high, CLK2 low), the circuit performs amplification with specific switch configurations. During the second phase (CLK2 high, CLK1 low), the circuit performs ADC comparison with different switch configurations. This temporal segmentation simplifies the control logic compared to spatial segmentation

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The circuit uses dynamic switching of capacitor connections and amplifier configurations through control switches SW1-SW6. The same physical components change their functional connections during operation, allowing the amplifier to dynamically transition between amplification mode (with feedback through C2) and comparison mode (with direct input to output connection), reducing the need for separate static circuit paths

Inventive Principle:
Principle #15Dynamics

Data Source

PatentUS8810701B2Image sensor system and amplifying/digitizing circuit therof for promoting performance while saving on power consumption and reducing the circuit area
Publication Date: 2014.08.19 HIMAX IMAGING LIMITED
  • US8810701B2 patent drawing
  • US8810701B2 patent drawing
  • US8810701B2 patent drawing

AI summary

An amplifying/digitizing circuit with a signal amplifying capability and a comparator capability is provided. The amplifying/digitizing circuit includes an amplifier having an input end and an output end, and a control circuit. The control circuit is coupled to the input end and the output end of the amplifier. When the amplifying/digitizing circuit is operated under an amplifying mode, the control circuit has a first configuration to receive a first input signal and makes the amplifier generate an output voltage at the output end according to the first input signal and an amplification factor. When the amplifying/digitizing circuit is operated under an ADC mode, the control circuit has a second configuration to receive a second input signal and makes the amplifier generate a comparison result according to the second input signal and the output voltage.