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Silicon Band-Gap Reference Voltage Generators Based On Dual Polysilicon Mos Transistors

IP.com Disclosure Number: IPCOM000099710D
Original Publication Date: 1990-Feb-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 2 page(s) / 56K

Publishing Venue

IBM

Related People

Dhong, SH: AUTHOR [+2]

Abstract

Disclosed is a circuit generating the silicon band-gap reference voltage for MOS applications. The unique feature employs two PMOS devices whose threshold voltages are different by the silicon band-gap voltage because of the degenerately doped P+ polysilicon and N+ polysilicon used as their gate materials.

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Silicon Band-Gap Reference Voltage Generators Based On Dual Polysilicon Mos Transistors

       Disclosed is a circuit generating the silicon band-gap
reference voltage for MOS applications.  The unique feature employs
two PMOS devices whose threshold voltages are different by the
silicon band-gap voltage because of the degenerately doped P+
polysilicon and N+ polysilicon used as their gate materials.

      In the CMOS process, the polysilicon used as the gate material
of a PMOS device can be doped P+ or N+, while keeping the rest of
the process the same.  The threshold voltages of the resulting PMOS
devices are different by the work-function difference of the
polysilicon, which is the silicon band-gap.  Fig. 1 shows a reference
circuit generating twice the silicon band-gap voltage.  The PMOS
devices 1 and 2 with P+ polysilicon gates are connected to the
current source 3, which is in turn connected to a power supply.  The
PMOS devices 4 and 5 with N+ polysilicon gates are connected to the
current source 6.  The current sources 3 and 6 are identical.  The
PMOS devices 1, 2, 4, and 5 have the same width and gate length.  The
inputs to the differential amplifier 10 are connected to the nodes 8
and 9.  The output node 7 of the differential amplifier 10 is
connected to the gate of the PMOS device 1.  The output voltage of
the differential amplifier is the same as the sum of the differences
of the threshold voltages of the devices 1 and 4, and 2 and 5. This
giv...