Substrate-Enhanced Comparator Latch for Low-Voltage Speed Limits
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Solution Overview
Problem
The speed of comparators is limited by restricted supply voltage and process characteristic frequency, making it difficult to achieve high-speed operation in low-voltage conditions.
Innovation Solution
A substrate-enhanced comparator is introduced, featuring a cross-coupled latch with additional substrate inputs that enhance positive feedback capability and latch speed by incorporating body transconductance and common-mode signals, allowing for high-speed operation even in advanced low-voltage processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If supply voltage is reduced to meet low-voltage requirements, then power consumption is reduced, but latch speed deteriorates due to limited process characteristic frequency
Solution Approach 1:
The patent introduces a substrate input terminal that couples to the substrate of the cross-coupled MOS transistors, adding a new control dimension beyond the traditional gate inputs. This substrate enhancement path operates in parallel with the gate control, providing an additional degree of freedom to accelerate latch regeneration without increasing supply voltage
Solution Approach 2:
The patent changes the control parameters of the MOS transistors by applying signals to the substrate terminal in addition to the gate terminal. By modulating the substrate potential through the AC coupler, the effective threshold voltage and transconductance of the transistors are dynamically adjusted to enhance latch speed under low-voltage conditions
2Volume of moving object
If supply voltage is reduced to meet low-voltage requirements, then device size can be reduced, but comparator speed deteriorates due to restricted supply voltage
Solution Approach 1:
The substrate input terminal provides an additional control dimension that enables speed enhancement without increasing the core comparator circuit size. The AC coupler and substrate terminal add minimal area compared to the overall device, achieving high speed in a compact low-voltage design
Solution Approach 2:
The AC coupler acts as an intermediary element that transfers and conditions signals from the output buffers to the substrate terminal. This intermediary component enables the substrate enhancement mechanism while maintaining proper signal levels and isolation, achieving high-speed operation without proportionally increasing device size
Data Source
AI summary
The present disclosure provides a substrate-enhanced comparator and electronic device, the comparator including: a cross-coupled latch, for connecting input signals to the gate of a cross-coupled MOS transistor to form a first input of the latch; output buffers, connected to the cross-coupled latch for amplifying output signals of the latch; AC couplers, connected to the output buffers for receiving and amplifying the output signals of the latch, coupling the output signals to substrates of the cross-coupled MOS transistors to form second inputs of the latch. The cross-coupled latch is also for output signal regenerative latching based on input signals sampled at the first inputs and input signals sampled at the second inputs. The present disclosure introduces additional substrate inputs to the cross-coupled structure of the conventional latch as the second inputs of the latch.