Darlington Pair BJT Sensor with Shared Base-Collector Layout
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Solution Overview
Problem
There is a need for sensors, particularly biosensors, that are accurate, sensitive, small, and mobile with reduced noise and high signal amplification, which can be easily integrated with semiconductor circuitry and inexpensively mass produced using standard semiconductor processes.
Innovation Solution
A Darlington pair sensor is disclosed, comprising an amplifying/horizontal bipolar junction transistor (BJT) and a sensing/vertical BJT. The amplifying BJT is horizontally disposed on a substrate, while the sensing BJT is vertically oriented. The two BJTs share a common extrinsic base/collector, which acts as the extrinsic base for the amplifying BJT and the collector for the sensing BJT, enabling dual-base operation with reduced noise and enhanced signal amplification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If sensors are separated from amplification circuitry over longer distances, then ease of manufacture is improved, but noise accumulation increases and signal quality deteriorates
Solution Approach 1:
The patent merges the sensor and amplification circuitry into a single integrated device structure. The sensor element is positioned in direct contact with the base of the bipolar junction transistor, eliminating the need for long external connections and thereby preventing noise accumulation while maintaining ease of manufacture through integration.
Solution Approach 2:
The patent employs a nested structure where the sensor is positioned within close proximity to the transistor base, and the amplification circuitry is integrated within the same device package. This nesting arrangement minimizes external connections and noise exposure while facilitating standardized manufacturing processes.
2Productivity
If standard semiconductor processes are used for mass production, then ease of manufacture and productivity are improved, but manufacturing precision and integration complexity may be limited
Solution Approach 1:
The patent utilizes parameter changes in the semiconductor fabrication process, specifically adjusting doping concentrations, layer thicknesses, and thermal processing conditions to achieve precise control over the sensor-transistor integration. This enables high-precision manufacturing using standard semiconductor process tools and techniques.
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 Darlington pair sensor achieves high signal amplification and reduced noise, enabling efficient integration with semiconductor circuitry while maintaining a compact and cost-effective design suitable for mass production.
Implementation Method 1
sensors utilizing bipolar junction transistors (BJTs) are well known in the art. BJTs are dependent on temperature and require temperature compensation in order to provide accurate and stable readings
Data Source
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AI summary
A Darlington pair sensor is disclosed. The Darlington pair sensor has an amplifying/horizontal bipolar junction transistor (BJT) and a sensing/vertical BJT and can be used as a biosensor. The amplifying bipolar junction transistor (BJT) is horizontally disposed on a substrate. The amplifying BJT has a horizontal emitter (652), a horizontal base (550), a horizontal collector (654), and a common extrinsic base/collector (350). The common extrinsic base/collector is an extrinsic base for the amplifying BJT. The sensing BJT has a vertical orientation with respect to the amplifying BJT. The sensing BJT has a vertical emitter (2950), a vertical base (1650), an extrinsic vertical base (2450), and the common extrinsic base/collector (350, in common with the amplifying BJT). The common extrinsic base/collector acts as the sensing BJT collector. The extrinsic vertical base is separated into a left extrinsic vertical base (2450L) and a right extrinsic vertical base (2450R) giving the sensing BJT has two separated (dual) bases, a sensing base and a control base. The Darlington pair sensor has high in-situ signal amplification with low noise and uses substrate space effectively.