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Light detection device

A technology of photodetection device and bias circuit, which can be used in measurement circuits, photometry using electrical radiation detectors, semiconductor/solid-state device components, etc., and can solve problems such as circuit occupation and disadvantage of smart cards.

Inactive Publication Date: 2004-04-21
ATMEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Finally, the aforementioned circuits occupy most of the useful semiconductor area, which again is not good for a smart card where space requirements are at a premium

Method used

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Embodiment Construction

[0011] refer to figure 1 , which shows a photodetection device 10 arranged to be integrated with an IC.

[0012] The device 10 comprises a first transistor 1 having a gate connected to a supply voltage Vdd, a source connected to a ground Vss, and connected to the supply voltage Vdd via a first high impedance resistor 3 a drain electrode. Thus, the transistor 1 is arranged to supply a bias current as will be described below.

[0013] A second transistor 2 of the device 10 has a gate connected to the drain of the first transistor 1, a source connected to a ground Vss, and connected to the supply voltage Vdd via a second high impedance resistor 4 A drain electrode 5, which is further connected to an output terminal 6. The high impedance resistor 4 is an undoped polysilicon resistor.

[0014] In operation, the gate of the transistor 2 is arranged to be reverse biased by receiving a bias current from the drain electrode of the first transistor.

[0015] When the drain electrod...

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PUM

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Abstract

A light detection device has a biasing transistor arranged to provide a bias current and a reverse biased transistor. The reverse biased transistor has a drain terminal coupled via a high impedance resistor to the supply voltage. Incident visible light is detected by a voltage drop at the drain electrode.

Description

technical field [0001] The present invention relates to light detection devices and in particular, but not exclusively, to light detection devices for tamper detection applications. Background technique [0002] In a semiconductor integrated circuit (IC), for example, a bank smart card, if the IC card falls into the hands of a dishonest person, it is vulnerable to security-related attacks. The IC card can be reversed to display or change the function and credit data contained in the IC card. Such an IC is known to have been desealed and even its passivation of the upper protective layer may have been removed. [0003] US Patent No. 4,952,796 describes a circuit that includes a current generator that generates current flow to a reverse biased transistor junction. If the transistor is illuminated, the reverse current in the junction increases and the voltage at the pole of the junction decreases. [0004] A problem with this configuration is that the input light will be at ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01L27/14G01J1/44H01L31/10
CPCH01L23/576G01J1/44H01L2924/3011H01L2924/0002H01L2924/00
Inventor 约翰·赫兰格雷厄姆·亨利·思塔特
Owner ATMEL CORP