Differential Transconductor Feedback for Fast Slew and Low Quiescent Current
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing differential transconductors face challenges in achieving high transconductance while minimizing quiescent current consumption, especially when the feedback potential equals the reference potential, and in providing efficient slew current performance.
Innovation Solution
A semiconductor device with a low power fast differential transconductor that includes a reference input stage, a feedback input stage, and a current limiting component, featuring a negative feedback path from the reference load to the current limiting component, which compensates for changes in total current and reduces quiescent current consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a differential transconductor is designed to provide high transconductance, then the output current response to voltage difference improves, but quiescent current consumption increases
Solution Approach 1:
The patent implements dynamic current control by using the negative feedback path to adjust the current through the reference input stage based on the voltage difference between reference and feedback potentials. When the voltage difference is zero, the current is minimized; when the voltage difference increases, the current increases to provide the necessary transconductance. This dynamic adjustment resolves the contradiction between maintaining high transconductance and minimizing quiescent current consumption.
Solution Approach 2:
The patent employs a negative feedback path from the reference load to the current limiting component that senses the voltage difference between reference and feedback potentials and adjusts the current accordingly. This feedback mechanism ensures that the transconductor only draws high current when actually needed (when voltage difference exists), while minimizing quiescent current when the potentials are equal, thus resolving the contradiction between transconductance performance and power consumption.
2Use of energy by moving object
If the transconductor is designed to minimize quiescent current when feedback potential equals reference potential, then power consumption reduces, but slew rate performance deteriorates
Solution Approach 1:
The current limiting component dynamically adjusts its resistance based on the voltage difference detected through the negative feedback path. During normal operation with small or zero voltage difference, the resistance is high to minimize quiescent current. During slew conditions with large voltage difference, the resistance decreases to allow high current flow and maintain fast slew rate. This dynamic behavior resolves the contradiction between minimizing quiescent current and maintaining slew rate performance.
Solution Approach 2:
The negative feedback path anticipates the need for high current during slew conditions by detecting the voltage difference early and preemptively adjusting the current limiting component to allow higher current flow. This preliminary action ensures that when a large voltage difference occurs, the transconductor is already prepared to deliver the necessary slew current, thus maintaining fast slew rate while keeping quiescent current low during normal operation.
Data Source
AI summary
A semiconductor device includes a low power fast differential transconductor, which provides an output current as a function of a difference between a reference potential input and a feedback potential input. The transconductance increases as an absolute value of the difference between the reference potential and the feedback potential increases. The transconductor includes a reference input stage to receive the reference potential and a reference load coupled in series with the reference input stage. The transconductor includes a feedback input stage to receive the feedback potential and a feedback load coupled in series with the feedback input stage. The transconductor further includes a current limiting component that is configured to control a total current through the reference input stage and the feedback input stage. The transconductor includes a negative feedback path from the reference load to the current limiting component, that compensates for changes in the total current due to differences between the reference potential and the feedback potential.