Self-Biased Voltage Comparator for Ultra-Low Static Power
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Solution Overview
Problem
Existing voltage comparators in portable electronic devices suffer from high static power consumption due to inefficient current distribution and the need for additional bias circuits, which reduces reliability and increases power consumption.
Innovation Solution
A voltage comparator design with self-biasing capabilities, featuring three branches of transistors (PMOS and NMOS) that eliminate the need for external bias signals, optimizing current flow and reducing power consumption by using current mirrors and a resistor to manage input voltages, resulting in a circuit with minimal static power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a tail current source IB is used in a common voltage comparator circuit, then the circuit can operate with a simple structure, but the static power consumption is high due to inefficient current distribution
Solution Approach 1:
The patent divides the single tail current source circuit into three separate branches, each with its own current source. This segmentation allows independent control of current in each branch, enabling the circuit to distribute current efficiently and avoid wasting 0.5*IB in the conventional configuration. The segmented structure resolves the contradiction by maintaining simplicity while eliminating the inherent inefficiency of unified current distribution.
Solution Approach 2:
The patent introduces dynamic current distribution control through three switches (S1, S2, S3) that can selectively connect or disconnect current sources based on operating conditions. This dynamic adjustment allows the circuit to adapt current flow to actual needs, preventing excessive current consumption while maintaining operational simplicity. The dynamic element transforms the static, inefficient current distribution into an adaptive system.
2Ease of manufacture
If NMOS transistors are used to form the tail current source IB, then the circuit can be implemented with standard components, but an additional bias circuit is required which increases power consumption
Solution Approach 1:
The patent implements self-biasing circuits in each of the three branches that automatically generate the required gate voltages for the NMOS transistors without external bias circuits. The self-biasing mechanism uses the circuit's own operating voltages to create the necessary gate control signals, eliminating the need for separate bias generation hardware. This resolves the contradiction by maintaining ease of implementation with standard NMOS components while removing the parasitic power consumption of external bias circuits.
3Use of energy by moving object
If the operating current is reduced to less than 100 nA to reduce power consumption, then power consumption decreases, but the reliability of the circuit is lowered
Solution Approach 1:
By segmenting the current into three separate branches, the patent allows the total current to be distributed across multiple paths. Each branch can operate at optimized current levels that maintain sufficient signal margins and noise immunity for reliable operation, while the combined power consumption remains below 100 nA. This segmentation resolves the contradiction by enabling reliable low-power operation that would be impossible in a single-branch configuration.
Solution Approach 2:
The patent applies different current levels and transistor sizing optimizations to each of the three branches based on their specific functional requirements. This local optimization allows each branch to contribute minimally to total power consumption while collectively maintaining the circuit's reliability through adequate signal levels and noise margins. The local quality principle resolves the contradiction by tailoring current distribution to actual operational needs in each branch.
Data Source
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AI summary
The present invention is applicable to electronic fields, and provides a voltage comparator. The voltage comparator includes a first branch, a second branch and a third branch. The first branch and the second branch both have self-biasing capabilities, and require no dedicated bias circuit. Under the same power voltage, the static power consumption of the voltage comparator is relatively low; fewer the power consuming branches exist in the circuit, and the reliability is high under low power consumption.