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Zero Temperature Coefficient Diode or Reference Element

IP.com Disclosure Number: IPCOM000048185D
Original Publication Date: 1981-Dec-01
Included in the Prior Art Database: 2005-Feb-08
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Walsh, RH: AUTHOR [+2]

Abstract

Shown is a convenient means to provide a voltage source or reference with a zero temperature coefficient. The total voltage drop of a Schottky barrier diode (SBD) is a function of the diode drop and the drop across the diode's series resistance. The temperature coefficient (TC) of forward voltage is negative for the diode drop and positive for the series resistance. Furthermore, the diode TC becomes less negative as the current density increases. It is possible then that the two TC components could be equal in magnitude and opposite in sign, resulting in a zero temperature coefficient at specific current densities. The value of the current density at which the zero TC occurs is a function of the diode parameters (barrier height, area, epi concentration, etc.).

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Zero Temperature Coefficient Diode or Reference Element

Shown is a convenient means to provide a voltage source or reference with a zero temperature coefficient. The total voltage drop of a Schottky barrier diode (SBD) is a function of the diode drop and the drop across the diode's series resistance. The temperature coefficient (TC) of forward voltage is negative for the diode drop and positive for the series resistance. Furthermore, the diode TC becomes less negative as the current density increases. It is possible then that the two TC components could be equal in magnitude and opposite in sign, resulting in a zero temperature coefficient at specific current densities. The value of the current density at which the zero TC occurs is a function of the diode parameters (barrier height, area, epi concentration, etc.).

An example of a zero temperature coefficient diode is shown in the graph. The three curves represent the IV characteristic at 90 degrees C, 60 degrees C and 30 degrees C. It can be seen that at I=900 microamps, a zero temperature coefficient exists. Since the area affects the current density and series resistance, the point at which zero TC occurs can most easily be moved by varying the diode area.

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