JPS5968027A - Variable output constant voltage circuit - Google Patents

Abstract

PURPOSE:To vary easily and electrically the output of a constant voltage circuit after the integrated circuit is manufactured, by using floating gate IGFETs as one of constant voltage circuit or plural IGFETs so that the threshold value is controlled. CONSTITUTION:An IGFET6 is of depletion type and composed of a floating gate IGFET whose threshold value is variable or two-layered insulation system IGFET of MNOS structure, etc. An IGFET7 is of floating gate type or represents the interface between two insulating films under the gate, and the threshold value is variable. The drain of this IGFET6 is connected to the plus side VDD 3 of a power source, and the gate and source are connected to the gate and drain of the other enhancement IGFET2, whose source is connected to the minus side VSS4 of the power source, so that a constant voltage output is delivered between a terminal 5 and the power source VSS4.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an insulated gate field effect transistor (hereinafter referred to as an insulated gate field effect transistor).
This relates to a constant voltage circuit in an integrated circuit built into a GFET (FET).Generally, in a constant voltage circuit used in an integrated GFET circuit, the output changes even when the power supply voltage changes. In other words, the circuit configuration was such that the output could be expressed in terms of the threshold value of the GIMCT.

Figure 1 shows an example of a conventional constant voltage circuit.
T1 is a depression type, the threshold value is VTD %, the value is KD, and GFBT2 is an enhancement type, the threshold value is VTR, and the value is KJ.7 terminals 5
The constant voltage output vconst between the negative llj Vllll+4 of the power supply and the power supply voltage is VTn, VT
Input KD, make χ, vcons t = VTIA JW VTD ・
It can be expressed as = -(1). From equation (1), the output Vconst is constant regardless of the power supply voltage. but,
Since the threshold and voltage values are determined during the manufacture of the integrated circuit, it is impossible to change the output voltage after manufacture.If you want to change the constant voltage output,
Methods such as preparing a T on an integrated circuit and replacing it by hanging it have been used, and it has been difficult to adjust the constant voltage output after the circuit is mounted.

An object of the present invention is to electrically easily vary the output of a constant voltage circuit after manufacturing an integrated circuit. This is an example. The engineering GFET 6 is a depletion type GFET with a floating gate under which the threshold value can be changed, or a two-layer insulating film type GFET such as an MNO8 structure. 7 in Fig. 2 is a floating gate or This indicates whether it is an interface between two insulating films under the gate, and indicates that the threshold value is a variable electronics GFET. The drain of this GFET is connected to the positive side VDD3 of the power supply, and the gate and source are both connected to the other enhancement GFFi.
IGF connected to the gate of T2 and the human train
The source of ET2 is connected to the negative side of the power supply V884.

A constant voltage output is output between the terminal 5 and the negative side Vss4 of the power supply.The present invention uses a floating gate structure as shown in FIG. 3 to freely control the threshold value of the GFFiT6. It is characterized by being a GFE or a two-layer insulating IGFKT such as the unconventional MNO8 structure shown in FIG.

As is well known, in the floating gate structure GFET shown in FIG. 3, the threshold value can be continuously changed by changing the amount of charge injected into the floating gate 8. In the two-layer insulating film system IG11'ET shown in FIG. 4, the threshold value can be changed by changing the amount of charge injected into the top of the interface 9 between the two insulating films.

As shown in equation (1), constant voltage output VC in Fig. 2
OnSt is the value of G'FKT6 with variable threshold value/
D and threshold value V'TD, and enhancement carving GI
l″BT20 with value KJ and threshold VTFI, vconet = VTI −J K'D/9
It is expressed as V”rD −・−・−(2). Therefore, by changing v′TD, V
const can be easily adjusted electrically in a circuit mounted state after manufacturing the integration port V.

Figure 5 shows an example of using a mechanical GFFliT10 that can control negative values, and Figure 6 shows an example that uses a mechanical GFFliT10 that can control negative values.
This is an example using 6 and 10. Figure 7 shows an example of a circuit configuration in which a constant voltage output is obtained between the terminal 5 and the positive side VDD 3 of the power supply. iT1 is an enhancement type, and GFKT6 is a depression engraving GE'ET capable of threshold control. In the case of Fig. 7, as shown in Figs. 2, 5, and 6, two
and 6 Isuwaka, or both can be controlled by threshold value.
It can be an FET. FIG. 8 is an example of a circuit using enhancement carving GFBTs 2 and 10. Figure 9 shows l5ch enhancement molding GFKT 11 and nc
Circuit examples using h depression molding carving FltT6, the 10th article includes four types of circuits GFFiT2a, 2b, 11.12
This is an example of the configuration. In the case of Figure 10, the engineering GFF: T
By using either or both of 11.12 as an IGFET capable of threshold control, the output can be varied.

As described above, according to the present invention, in an integrated circuit constituted by GFETs, one or more GFKTs in the constant voltage circuit are configured as floating gate GFETs in order to enable precise control of the value. In the past, the output of the constant voltage circuit, which was fixed at the time of manufacturing the accumulation port,
After manufacturing, electrical changes can be easily made even in the circuit mounted state.

[Brief Description of the Drawings] Fig. 1 is a conventional constant voltage circuit diagram, Fig. 2 is a constant voltage circuit diagram according to the present invention, and Fig. 3 is a floating voltage circuit diagram for varying the threshold value, which is the gist of the present invention. Gate structure IGFBT (in this case M
Figure 4 also shows a cross-sectional structure diagram of a two-layer insulating film type GFET (in this case, an M
Figure 5 to Figure 9 are the cross-sectional structural diagrams of the GFKT of the present invention (No. It is a constant voltage circuit based on 1...Depression?nch GFF
iT2...Enhancement) ff, nch
GFET6・・・・・・Positive side terminal of power supply VDD
4... Negative side terminal of power supply V8B5...
...Output terminal 6...Variable threshold value ftrrQh GFET
(Depression type) 7... Floating gate dimensions or two-layer insulation film interface 8...
... Floating gate 9 ... Two-layer insulating film interface 10 ... Highly variable frnch engineering GFET
(Enhancement type) 11...Enhancement type pch engineering GNET
12... More than pch GFET with variable threshold value 7- Figure 1 Figure 3 Figure 4- 111111111Ei-1

Claims (3)

[Claims] (1) In an integrated circuit composed of insulated gate field effect transistors, at least one of the insulated gate field effect transistors of a constant voltage circuit composed of at least two insulated gate field effect transistors is A variable output constant voltage circuit characterized by using a field effect transistor whose output is variable; (2) A variable output constant voltage circuit according to claim 1, wherein the field effect transistor whose threshold value is variable is a floating game IE lightning field effect transistor; (3) Two field-effect transistors with variable thresholds
2. A constant voltage circuit with a variable output voltage according to claim 1, which is a field effect transistor based on a layered insulating film.