Comparator Circuit With Follower-Inverter Offset Compensation
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Solution Overview
Problem
Current comparator implementations face challenges due to the need for closely matched transistors, which can lead to errors in accuracy due to transistor variations, and existing solutions do not effectively address the issue of offset voltages and linearity in comparator circuits.
Innovation Solution
A comparator design that includes a follower stage and an inverter stage with controllable switching and filtering, using tuning means to adjust offset voltages and signal conditioning to improve accuracy, and utilizing N-type or both N-type and P-type transistors to achieve high accuracy and linearity by offsetting threshold voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If closely matched transistors are used in differential mirror current configuration, then comparator accuracy is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent changes the operating parameters by using source-coupled logic with reference controlled inputs instead of differential mirror current, and by applying specific voltage levels to control the transistors' operating states, thereby achieving accuracy without requiring close transistor matching
Solution Approach 2:
The patent introduces reference controlled inputs as an intermediary mechanism that controls the transistor operations, allowing the comparator to achieve precision through controlled voltage references rather than through transistor matching
2Ease of manufacture
If transistor variations are present, then manufacturing ease is improved, but comparator accuracy deteriorates due to amplified error effects
Solution Approach 1:
The patent employs feedback mechanisms through the reference controlled inputs that monitor and adjust the transistor operations, compensating for variations and preventing error amplification while maintaining manufacturing ease
Solution Approach 2:
By changing the control parameters to use reference voltages and source-coupled logic, the system becomes insensitive to transistor variations, allowing standard manufacturing processes to produce accurate comparators
3Device complexity
If offset voltages are not compensated, then device simplicity is maintained, but measurement precision deteriorates
Solution Approach 1:
The patent introduces reference controlled inputs as intermediary elements that provide controlled voltage references to compensate for offset voltages, achieving precision without significantly increasing circuit complexity
Data Source
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AI summary
A comparator is disclosed, for comparing a first input voltage (e+) with a second input voltage (e-) and generating a corresponding output voltage (out). The comparator comprises: a first input terminal (e+) for receiving the first input voltage: a second input terminal (e-) for receiving the second input voltage; an output terminal (out) for outputting the output voltage; a first supply rail (VCC) for providing a first supply voltage; and a second supply rail (VDD) for providing a second supply voltage. The comparator further comprises: a follower stage comprising a first follower stage supply terminal coupled to the first supply rail, a second follower stage supply terminal coupled to the second supply rail, a follower stage input terminal coupled to the second input terminal, and a follower stage output terminal for providing a follower stage output voltage; and an inverter stage comprising a first inverter stage supply terminal coupled to the first supply rail, a second inverter stage supply terminal coupled to the follower stage output terminal, an inverter stage input terminal coupled to the first input terminal, and an inverter stage output terminal for providing an inverter stage output voltage and coupled to the output terminal.