Three-Stage Amplifier With Segmented Passbands For Low Power
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Solution Overview
Problem
Conventional power supply error-amplifier circuits consume high standby and operational currents, making them unsuitable for low-power applications like smartphones and tablets, where they fail to maintain stability and linearity while extending battery life.
Innovation Solution
A power supply design incorporating a three-stage amplifier with operational transconductance amplifier stages and a feedback network, which separates the frequency passbands to independently compensate for input offsets and signal characteristics, reducing current consumption and improving power efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional power supply error-amplifier circuits are used, then stability and linearity are maintained, but current consumption is high
Solution Approach 1:
The amplifier is divided into three distinct stages with separate passbands: first stage (lower frequency), second stage (higher frequency), and third stage (output). Each stage operates independently with its own input offset characteristics, allowing separate compensation and reducing the need for high current consumption to maintain stability across the entire bandwidth.
Solution Approach 2:
Each amplifier stage is designed with specific local characteristics - the first stage handles lower frequencies with its own offset compensation, the second stage handles higher frequencies independently, and the third stage combines their outputs. This local optimization allows each stage to operate efficiently at its designated frequency range without requiring excessive current to maintain overall stability.
2Use of energy by moving object
If multi-stage amplifiers are used to reduce current consumption, then power efficiency improves, but input offset reflection between stages may occur
Solution Approach 1:
The frequency spectrum is segmented into distinct passbands for each stage. The first stage operates in a lower frequency passband, the second stage in a higher frequency passband, and their non-overlapping frequency ranges prevent input offset reflection between stages. Each stage processes signals within its designated frequency range independently.
Solution Approach 2:
The third stage acts as an intermediary that combines the outputs of the first and second stages. It receives signals from both stages at its input nodes and produces a combined output, effectively isolating the first and second stages from direct interaction and preventing offset reflection while maintaining power efficiency.
Data Source
AI summary
In an embodiment, an amplifier includes first, second, and third stages, and a feedback network. The first stage has a first passband and is configured to generate a first output signal in response to first and second input signals, and the second stage has a second passband that is higher in frequency than the first passband and is configured to generate a second output signal in response to third and fourth input signals. The third stage has a first input node coupled to receive the first output signal, a second input node coupled to receive the second output signal, and an output node. And the feedback network is coupled between the second input node and the output node of the third stage. For example, where the first, second, and third stages are respective operational-transconductance-amplifier stages, such an amplifier may be suitable for low-power applications.