Self-Biased Comparator Circuit for Low-Noise High-Speed Voltage Comparison
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Solution Overview
Problem
Existing comparators for power and high-speed applications face limitations, including the need for external bias circuitry, high-frequency clocks that introduce noise, and the inability to compare non-fixed voltages, which restricts their effectiveness in low-voltage differential high-speed applications.
Innovation Solution
A comparator design that includes self-biased inverters with voltage-controlled resistors, eliminating the need for external bias circuitry and high-frequency clocks, and allowing comparison of two non-fixed voltages by using voltage-controlled resistors to adjust the reference and threshold voltages dynamically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external bias circuitry is used in comparators, then the comparator can perform voltage comparisons, but the device complexity increases and power consumption increases
Solution Approach 1:
The comparator circuit performs self-biasing through the feedback connection from the first inverter output to its input, eliminating the need for external bias circuitry. The circuit generates its own operating point automatically, reducing device complexity while maintaining comparator functionality.
Solution Approach 2:
The biasing function is merged into the main comparator operation by using the feedback path from the first inverter. The same inverter that performs comparison also provides the biasing function through its feedback connection, reducing the need for separate bias circuitry.
2Speed
If high-frequency clocks are used in comparators, then high-speed comparisons can be achieved, but noise is introduced
Solution Approach 1:
The circuit uses periodic switching action through the feedback mechanism rather than continuous high-frequency clocking. The feedback connection creates natural oscillation and switching behavior that achieves high-speed comparison without requiring external high-frequency clock signals, thereby reducing noise.
Solution Approach 2:
The mechanical clocking system is replaced with an electronic feedback mechanism. Instead of using external clock signals to drive the comparison, the circuit uses internal feedback to achieve the necessary switching action, eliminating the noise associated with high-frequency clock distribution.
3Device complexity
If fixed reference voltages are used in comparators, then simple circuit design is achieved, but the ability to compare non-fixed voltages is lost
Solution Approach 1:
The circuit achieves dynamic adaptability through the feedback connection that allows the reference voltage to adjust automatically based on the input signal. The first inverter's feedback creates a dynamic operating point that can track and compare non-fixed voltages, providing versatility without requiring complex external reference voltage generation circuits.
Data Source
AI summary
In certain aspects, a comparator includes a first inverter having an input, an output, and a voltage supply input, wherein the input of the first inverter and the output of the first inverter are coupled together, and the voltage supply input of the first inverter is configured to receive a first compare voltage. The comparator also includes a second inverter having an input, an output, and a voltage supply input, wherein the input of the second inverter is coupled to the output of the first inverter, and the voltage supply input of the second inverter is configured to receive a second compare voltage.