Two-Stage Current Mirror Amplification for Fingerprint Photocurrents
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Solution Overview
Problem
Current fingerprint recognition technologies face challenges in accurately amplifying small photocurrents from photodiodes in mobile devices, leading to device accuracy issues and difficulties in integrating large resistance resistors for amplification, which complicates precision and integration.
Innovation Solution
A current amplification circuitry comprising a voltage control circuit, first current amplification circuits with current mirrors, and a second current amplification circuit, where the current mirror performs a first stage of amplification, reducing the amplification factor requirements for the second stage and allowing for integration of smaller resistance values, facilitating high precision and simplifying device structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If large resistance resistors are used for amplification, then amplification accuracy is improved, but device integration becomes difficult and structure complexity increases
Solution Approach 1:
The amplification process is divided into two stages: a first current amplification circuit that performs initial amplification, and a second current amplification circuit that performs further amplification. This segmentation allows each stage to use smaller resistance values while achieving the overall high amplification factor needed for accurate photocurrent measurement, thereby improving integration feasibility without sacrificing measurement precision
Solution Approach 2:
The first current amplification circuit acts as an intermediary between the photodiode and the second current amplification circuit. It converts the extremely small photocurrent into a larger current that can be more easily handled and further amplified by the second stage, eliminating the need for the second stage to use large resistance values and thus simplifying the overall device structure
2Measurement precision
If large resistance resistors are used for amplification, then amplification accuracy is improved, but manufacturing precision requirements increase
Solution Approach 1:
By dividing the amplification into two stages, each stage can use resistors with smaller and more manageable resistance values. This segmentation reduces the manufacturing precision requirements for each individual resistor, as smaller resistance values are easier to fabricate with high precision using standard semiconductor processes, while still achieving the required overall amplification accuracy
3Measurement precision
If multi-stage amplification is implemented, then amplification capability is improved, but device structure complexity increases
Solution Approach 1:
The first and second current amplification circuits are integrated into a unified circuit architecture where the output of the first stage directly feeds into the second stage. This merging approach allows the multi-stage amplification to be implemented in a compact manner that minimizes the increase in device structure complexity while maximizing the amplification capability for accurate photocurrent detection
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed solution effectively amplifies photocurrents with reduced resistance values, enhancing device precision and integration capabilities, while simplifying the structure and manufacturing process of fingerprint recognition sensors.
Implementation Method 1
The current mirror is coupled to a voltage input terminal, the voltage control circuit, and a first input terminal of the second current amplification circuit, respectively. The current amplification circuitry can be configured to amplify a current from the voltage input terminal according to the voltage control signal provided by the voltage control circuit
Data Source
AI summary
Embodiments of the present disclosure provide a current amplification circuitry and a driving method thereof, and a fingerprint detection device. The current amplification circuitry includes a voltage control circuit, a plurality of first current amplification circuits, and a second current amplification circuit. The voltage control circuit provides a voltage control signal to the plurality of first current amplification circuits. The first current amplification circuit includes a current mirror, and the current mirror is coupled to a voltage input terminal, the voltage control circuit, and a first input terminal of the second current amplification circuit. The first current amplification circuit amplifies a current from the voltage input terminal according to the voltage control signal provided by the voltage control circuit, and provides the amplified current to the second current amplification circuit. The second current amplification circuit is coupled to the voltage input terminal via a second input terminal and amplifies the amplified current.