Cascode Comparator Circuit With Amplitude Limiting for Low Kickback
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Solution Overview
Problem
In comparators with cascode transistors, the potential variation of the main node of the differential transistor increases during linear operation, leading to increased kickback to the input.
Innovation Solution
A comparator design that includes a first differential transistor, a second differential transistor, load transistors, cascode transistors, and an amplitude limiting element to prevent the cascode transistor from entering a linear operation state, thereby reducing kickback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a cascode transistor is used to reduce noise, then noise reduction is achieved, but the cascode transistor may enter linear operation state causing increased potential variation and kickback to input
Solution Approach 1:
An amplitude limiting element is introduced as an intermediary component between the cascode transistor and the output node. This element limits the amplitude of output signals to prevent the cascode transistor from entering linear operation, thereby eliminating kickback to the input while preserving the noise reduction benefit of the cascode configuration
Solution Approach 2:
The amplitude limiting element dynamically adjusts or constrains the output signal amplitude parameter. By limiting the amplitude to a predetermined range, the operating point of the cascode transistor is maintained within the saturation region, preventing linear operation and the associated kickback effect
Data Source
AI summary
A comparator according to an embodiment of the present disclosure includes a first differential transistor and a second differential transistor forming a differential pair, a first load transistor and a second load transistor respectively provided corresponding to the first differential transistor and the second differential transistor, and a first cascode transistor connected in cascode between the first differential transistor and the first load transistor.