Gain-Boosted Dynamic Comparator for Low-Noise Signal Latching
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Solution Overview
Problem
Conventional two-stage dynamic comparators have limited gain due to transconductance constraints, which affects noise performance and requires enhancement for higher gain and longer amplification periods.
Innovation Solution
A dynamic comparator design incorporating a dynamic amplifier with two input pairs and a gain-boosting circuit, where the first input pair and a current source are used to amplify signals, and a latch circuit to generate output signals, with clock signals controlling the current sources to optimize gain and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional two-stage dynamic comparator is used, then the comparator can operate at low supply voltage and high speed, but the gain is limited due to transconductance constraints which degrades noise performance
Solution Approach 1:
The comparator is divided into two distinct stages: a dynamic amplifier stage for signal amplification and a latch stage for signal latching. This segmentation allows each stage to be optimized independently - the amplifier stage can focus on maximizing gain during the amplification phase while the latch stage ensures stable signal storage, thereby improving overall noise performance without sacrificing gain
Solution Approach 2:
The dynamic amplifier performs preliminary amplification of the differential input signal before the latch stage processes it. By pre-amplifying the signal with high gain in the first stage, the signal-to-noise ratio is improved before latching, allowing the comparator to achieve better noise performance while maintaining the required gain
2Measurement precision
If the amplifier gain is increased to improve noise performance, then the noise performance improves, but the amplification phase duration must be extended which increases power consumption
Solution Approach 1:
The comparator operates in periodic cycles with distinct amplification phases and latch phases. During the amplification phase, the dynamic amplifier operates at high gain to improve noise performance. During the latch phase, the amplifier is disabled and the latch holds the amplified signal. This periodic operation allows high gain to be achieved only when necessary, reducing overall power consumption compared to continuous high-gain operation
Solution Approach 2:
The comparator uses dynamic switching between different operational modes - during the amplification phase, the dynamic amplifier is active with high gain; during the latch phase, the amplifier is turned off and the latch circuit takes over. This dynamic operation allows the system to achieve high noise performance during signal processing while minimizing power consumption during signal storage
3Reliability
If a single input pair is used, then the device complexity is low, but the gain is limited and amplification phase is short
Solution Approach 1:
The input stage is segmented into two separate input pairs: one dedicated to the dynamic amplifier and another to the latch circuit. This segmentation allows each input pair to be optimized for its specific function - the amplifier input pair maximizes gain while the latch input pair ensures stable signal capture. Although this increases device complexity, it enables the system to achieve higher gain and longer amplification phase duration
4Reliability
If the amplification phase is extended to maintain higher gain, then the gain is maintained, but the operation speed decreases
Solution Approach 1:
The comparator uses periodic switching between amplification and latch phases. The amplification phase is extended sufficiently to maintain high gain and improve noise performance, while the latch phase quickly captures the amplified signal. This periodic operation allows the system to maintain high gain for the necessary duration without permanently slowing down the overall operation speed
Data Source
AI summary
The present invention provides a dynamic comparator including a dynamic amplifier and a latch circuit. The dynamic amplifier includes a first input pair, a current source and a gain boosting circuit. The first input pair is configured to receive an input signal to generate an amplified signal at an output terminal. The current source is coupled between the first input pair and a first reference voltage. The gain-boosting circuit is coupled between the first input pair and a second reference voltage, and is configured to receive the input signal to selectively inject current to the output terminal or sink current from the output terminal. The latch circuit is coupled to the dynamic amplifier, and is configured to receive the amplified signal to generate an output signal.