Pipeline A/D Converter First-Stage DAC Layout for Lower Power
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Pipeline A/D converters face challenges in reducing power consumption while maintaining high speed and accuracy, particularly as the number of pixels in CCD cameras increases, leading to increased power consumption and complexity in the DA conversion portion due to the need for multiple voltage supply portions and capacitors.
Innovation Solution
The first stage of the pipeline A/D converter is configured to perform A/D conversion of multiple bits using a combination of primary and auxiliary voltage supply portions, reducing the number of voltage supply portions and increasing the size of input capacitors, thereby reducing power consumption and preventing an increase in the area of the DA conversion portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of voltage supply portions is increased to maintain accuracy in multi-bit A/D conversion, then measurement precision is improved, but device complexity and area increase
Solution Approach 1:
The voltage supply portions are segmented into primary voltage supply portions (first through fourth) and auxiliary voltage supply portions (fifth through eighth). Each segment handles specific voltage levels, allowing the system to maintain high conversion accuracy while organizing complexity into manageable, modular units. The primary portions handle main voltage levels while auxiliary portions provide additional precision levels.
Solution Approach 2:
The patent introduces a hierarchical dimension to voltage supply organization by categorizing voltage portions into primary and auxiliary groups. This dimensional organization allows the system to manage multiple voltage levels systematically, reducing the perceived complexity while maintaining the necessary number of voltage supply portions for high-precision multi-bit A/D conversion.
2Measurement precision
If the number of voltage supply portions is increased to maintain accuracy in multi-bit A/D conversion, then measurement precision is improved, but the area of the DA conversion portion increases
Solution Approach 1:
Multiple voltage supply portions are merged into integrated circuit blocks where shared infrastructure (power rails, control logic, routing) serves multiple voltage generation functions. The primary and auxiliary voltage supply portions share common control mechanisms and physical infrastructure, reducing the total area required compared to completely separate voltage supply circuits.
Solution Approach 2:
The voltage supply portions are designed with multi-functionality, where the same physical infrastructure supports multiple voltage levels and conversion functions. The DA conversion portion uses shared control logic and routing structures that serve both primary and auxiliary voltage supply functions, thereby reducing overall area consumption while maintaining the capability to provide multiple precise voltage levels.
3Measurement precision
If more voltage supply portions are used for multi-bit conversion, then A/D conversion accuracy is maintained, but power consumption increases
Solution Approach 1:
The voltage supply portions operate in a periodic, clocked manner synchronized with the A/D conversion process. Voltages are supplied and switched at specific timing intervals rather than continuously, reducing power consumption. The periodic switching of voltage levels in the DA conversion portion minimizes unnecessary current flow while maintaining conversion accuracy during active periods.
Solution Approach 2:
The system recovers and reuses voltage levels through the coordinated operation of primary and auxiliary voltage supply portions. Instead of continuously generating all voltage levels, the system selectively activates portions based on conversion needs, allowing inactive voltage supply circuits to enter low-power states. The coordinated switching between primary and auxiliary portions enables efficient power usage by activating only the necessary voltage levels at any given time.
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, minimizes the area of the DA conversion portion, and maintains relative accuracy, avoiding increases in complexity and routing issues, while allowing for larger input capacitors to ensure accuracy.
Implementation Method 1
When the dock Φ1 is L and the dock Φ2 is H, the switches 9 and 10 are OFF and the switch 11 is ON, so that the electric charge sampled by the input capacitor Cs is redistributed to the input capacitor Cs and the feedback capacitor Cf
Implementation Method 2
The AD conversion portion 3 converts the input analog signal supplied to a current stage into a ternary digital signal, and outputs the same
Implementation Method 3
The DA conversion portion 4 converts the digital signal output from the AD conversion portion 3 into an analog signal so as to generate an analog reference signal
Implementation Method 4
The remainder operation portion 5 subtracts the analog reference signal output of the DA conversion portion 4 from the input analog signal supplied to the current stage, and amplifies the obtained analog signal
Data Source
AI summary
In each of a plurality of stages, an input analog signal is quantized, so that a digital signal corresponding to each part of bits is generated. ADA conversion portion generates an analog reference signal based on the digital signal, and a remainder operation portion performs addition/subtraction and amplification by a predetermined factor with respect to the input analog signal. Then, the signal thus obtained is supplied to a subsequent stage. The DA conversion portion in the first stage where A/D conversion of a plurality of bits is performed includes primary voltage supply portions capable of outputting a reference voltage at one of a plurality of levels, and an auxiliary voltage supply portion capable of outputting a reference voltage at an auxiliary level different from the above-described level. The respective voltage supply portions selectively output the reference voltages based on a digital signal generated by an AD conversion portion. Based on a combination of the output reference voltages, the analog reference signal in accordance with the digital signal is generated. It is possible to reduce power consumption while suppressing an increase in the area of an element.