Complementary Switched-Capacitor Amplifier for Low-Power Pipelined ADCs
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional pipelined analog-to-digital converters (ADCs) using switched capacitor technology with class-A transconductance amplifiers suffer from inefficient charge transfer, leading to high power consumption and limited bandwidth due to constant current draw with only a small fraction being utilized.
Innovation Solution
The implementation of a complementary push-pull transconductance amplifier with a switched capacitor network and additional switches, allowing for improved charge transfer efficiency and increased bandwidth by utilizing two complementary amplifying elements and level-shifting capacitors to enhance power efficiency and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a class-A transconductance amplifier with switched capacitor technology is used in the conventional MDAC, then the circuit provides stable operation and reliable charge transfer, but the charge transfer efficiency is low resulting in high power consumption
Solution Approach 1:
The amplifier is segmented into two complementary amplifying elements (first and second amplifying elements) that operate in a push-pull configuration. Each element handles different portions of the signal cycle, allowing the circuit to maintain stable operation while reducing overall power consumption by activating only the necessary element at any given time.
Solution Approach 2:
The invention changes the operational parameters by using complementary amplifying elements with different biasing conditions. The first amplifying element operates with a first bias current and the second with a second bias current, allowing optimization of power consumption while maintaining reliable charge transfer through parameter adjustment.
2Stability of the object's composition
If a class-A transconductance amplifier draws constant current, then the amplifier maintains stable biasing and linear operation, but the bandwidth is limited due to inefficient current utilization
Solution Approach 1:
The invention introduces dynamic operation by using switched capacitor technology with the complementary amplifying elements. The amplifiers switch between different operational states based on the input signal, allowing the biasing to be stable during each state while enabling faster signal processing and increased bandwidth through the switching action.
Solution Approach 2:
The switched capacitor network operates in periodic phases (sampling phase and conversion phase), with the complementary amplifying elements activated periodically. This periodic action allows stable biasing during each phase while achieving higher effective bandwidth through the time-multiplexed operation.
3Stability of the object's composition
If only a small fraction of the constant current is delivered to the load, then the amplifier maintains stable operation, but the power efficiency is poor affecting the pipelined ADC performance
Solution Approach 1:
The current delivery is segmented between two complementary amplifying elements. Each element is optimized to deliver current efficiently during its active phase, improving overall power efficiency while maintaining stable operation through the complementary nature of the segmentation.
Solution Approach 2:
The complementary push-pull configuration ensures that one amplifying element is always active and delivering useful current to the load. This continuity of useful action eliminates the idle periods present in single-ended designs, improving power efficiency while maintaining stable operation.
Data Source
AI summary
The present disclosure is directed to a switched capacitor amplifier that includes a switched capacitor network and a complementary push-pull amplifier. The switched capacitor amplifier of the present disclosure can provide a larger fraction of the charge provided by a power supply and flowing through the amplifier to a capacitive load at the output of the amplifier compared to switched capacitor amplifiers that use single-ended class-A amplifiers. The switched capacitor amplifier of the present disclosure can be used in a converter stage of a pipelined analog-to-digital converter (ADC) to improve the ADC's power efficiency and/or bandwidth. It can be further generalized to be used in other applications other than pipelined ADCs.