Current Pre-Amplifier With Dynamic Biasing for Fast Low-Power Detection

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Solution Overview

Problem

Existing rapid current comparators require high static consumption to achieve short response times, making them unsuitable for applications where low power consumption is crucial, such as in relief imaging where rapid measurement is essential.

Innovation Solution

A current pre-amplifier with a regulated cascode stage and feedback mechanisms, including current mirrors and capacitors, to dynamically increase the polarisation current only during signal detection, reducing static consumption and enhancing response speed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If high static consumption is used to polarise the inverter in traditional CMOS current comparators, then the response time is reduced (improved speed), but the power consumption increases significantly

Engineering Contradiction:

Improveresponse timeVSAvoidpower consumption

Core Design Contradiction:

SpeedVSUse of energy by moving object

Solution Approach 1:

The patent implements dynamic polarisation by replacing static inverter biasing with a regulated cascode stage that dynamically adjusts the polarisation current based on input signal presence. The circuit transitions from a static high-consumption state to a dynamic state where current is only elevated when detection is needed, resolving the contradiction between speed and power consumption.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the operating parameters of the comparator by using feedback mechanisms that adjust the polarisation current magnitude based on detection requirements. The feedback means modify the current supplied by the current generators, allowing the system to operate at low consumption during idle periods and switch to high-performance mode only when signals need detection.

Inventive Principle:

Principle #35Parameter changes

2Speed

If the inverter is polarised in perfect balance around the switch point to achieve good rapidity, then the response time improves, but the static consumption increases to more than 500 μW

Engineering Contradiction:

ImproverapidityVSAvoidstatic consumption

Core Design Contradiction:

SpeedVSUse of energy by stationary object

Solution Approach 1:

The patent extracts the polarisation function from the traditional inverter-based architecture and relocates it to a separate regulated cascode stage. This separation allows the main comparison circuit to operate with minimal static consumption while the dedicated cascode stage handles the dynamic polarisation requirements, achieving rapidity without the 500 μW static consumption penalty.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces feedback mechanisms that continuously monitor the detection state and adjust the polarisation current accordingly. The feedback means detect when input current pulses are present and only then increase the current supplied by the current generators, eliminating the need for continuous high static consumption while maintaining the ability to achieve rapid response when needed.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS7642860B2Current pre-amplifier and associated current comparator

Publication Date: 2010.01.05 COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES

AI summary

A current pre-amplifier with an input capable of receiving or supplying an input current with at least one pulse, wherein the pre-amplifier includes a regulated cascode stage including an input transistor and a first current generator as well as an output transistor and a second current generator. The pre-amplifier includes a detection device capable of detecting an input current pulse, and a feedback device capable of increasing the current supplied by the first and/or the second current generator during the entire detection of the input current pulse.