Integrated-Latch Comparator for High-Bandwidth Low-Power ADCs
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Solution Overview
Problem
Designing comparators for high-speed analog-to-digital converters (ADCs) poses challenges due to the need for high bandwidth, low power consumption, and fast signal acquisition and latching, particularly in time-interleaved architectures where power consumption increases with the number of comparators.
Innovation Solution
The integration of a pre-amplifier within the latch and capacitive level-shifting in the latch allows for direct driving of the latch during the acquire phase, reducing power consumption and enhancing speed, eliminating the need for a separate pre-amplifier and minimizing static current burn during the regeneration phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a separate pre-amplifier is used before the latch, then the signal amplification is improved, but the power consumption and circuit area increase
Solution Approach 1:
The patent merges the pre-amplifier and latch into a single integrated circuit block. The pre-amplifier stage is directly coupled to the latch without requiring a separate physical component, thereby achieving signal amplification while reducing overall power consumption and circuit area. This integration allows the pre-amplifier to drive the latch directly, eliminating the need for additional buffer stages or separate amplification components.
2Measurement precision
If a separate pre-amplifier is used before the latch, then the signal amplification is improved, but the circuit area increases
Solution Approach 1:
The pre-amplifier and latch are merged into a single integrated circuit block, sharing common substrate area and interconnect structures. This integration significantly reduces the total circuit area compared to having separate pre-amplifier and latch components, while maintaining the necessary signal amplification functionality through direct coupling between the pre-amplifier output and latch input.
3Speed
If the comparator is designed for high bandwidth, then the signal acquisition speed is improved, but the power consumption increases
Solution Approach 1:
The comparator employs dynamic operation modes where the circuit switches between different operational states based on the input signal conditions. During the acquisition phase, the circuit operates in a high-bandwidth mode with optimized current paths for fast signal response. During the regeneration phase, the circuit transitions to a lower power state, dynamically adjusting operational parameters to achieve high speed when needed while minimizing power consumption during stable operation.
Solution Approach 2:
The comparator uses periodic clocked operation with distinct phases including acquisition, regeneration, and reset. During the brief acquisition phase, the circuit operates at high bandwidth to capture the input signal quickly. During the regeneration phase, the circuit maintains sufficient bandwidth while reducing power consumption through controlled current switching. This periodic operation allows the comparator to achieve high signal acquisition speed during critical phases while maintaining lower average power consumption.
Data Source
AI summary
Comparators are implemented in many circuits, including analog-to-digital converters (ADCs). Some ADCs demand high bandwidth, low power consumption, and high speed. To address these requirements, a comparator circuit can be implemented without a separate pre-amplifier, where a sampling network drives a latch directly. Specifically, the comparator circuit integrates a pre-amplifier within the latch in a manner that ensures low power and high speed operation.