JPH1187628A - Semiconductor integrated circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reference voltage generating circuit, wherein a stable reference voltage is generated without increasing the circuit scale and power consumption, etc. SOLUTION: In a semiconductor integrated circuit having a built-in reference voltage generating circuit, a constant current part 2 (junction gate type transistor) and a constant voltage part 22 (constant voltage diode) of the reference voltage generating circuit are constituted, using an SOI(silicon-on-insulator) device. Further, a volume-occupying P-type or N-type semiconductor region (11-16) which constitute the SOI device is kept to such volume as of constant temperature through the operation current of the reference voltage generating circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor integrated circuit having a built-in reference voltage generating circuit.

[0002]

2. Description of the Related Art As shown in FIGS. 3, 4 and 5, a reference voltage generating circuit includes a + Vcc electrode N1 and a GND electrode N3.
And to generate a stable reference voltage from the Vref electrode N2. Therefore, in order not to be affected by the fluctuation of the power supply voltage, the basic structure has a circuit configuration for supplying the constant current Iz from the constant current unit 21 to the constant voltage unit 22 as shown in FIG. .

Further, in this circuit, since the thermal stability of the reference voltage becomes a problem, the following countermeasures are usually taken.

The first method uses a temperature compensation method. As shown in FIGS. 4 and 5, a temperature drift source (transistors Q1, Q1 ', Q2', Q3 ', diode Di) is used.
1, Di2, Zener diode Dz, resistors R1, R
2, R1 ', R2', R3 ') are configured so that the temperature coefficients cancel each other and become zero.

The second method is based on temperature management, in which a thermosensitive element and a heating element are placed in the vicinity of a reference voltage generating circuit, and the substrate temperature is kept constant by a temperature control circuit for controlling the amount of generated heat (power). Things.

For example, in Japanese Unexamined Patent Publication No. 55-74166, as shown in FIG. 6, in order to keep the temperature of the semiconductor element 41 constant, a temperature sensing temperature sensing element is provided in the semiconductor element 41. The element 42 is incorporated and the semiconductor element 4
1, a heat-generating resistor film 43 provided immediately below
Via 44, it is connected to a DC control power supply 45 controlled by the output from the temperature sensing element 42. The DC control power supply 45 controls the current supplied to the heating resistor film 43 by a signal from the temperature sensing element 42, so that the temperature of the semiconductor element 41 can be kept constant.

In Japanese Unexamined Patent Publication No. 5-235127, as shown in FIG. 7, the temperature of an SOI device 51 having an active element to be temperature-controlled on an insulating layer formed on a substrate is disclosed. In order to keep
A first thin film 52 and a second thin film 53 are stacked on an OI device 51 via a surface passivation film, and a bonding layer is formed. Also, the first thin film 52 and the second thin film 53
Are connected to an electromotive force detection circuit 54 and a current control circuit 55, respectively. The electromotive force detection circuit 54 detects the temperature by the Seebeck effect of the bonding layer, and the current control circuit 55 controls the supply current based on the detected temperature. The temperature is controlled by heat generation or heat absorption by the Peltier effect of the bonding layer.

[0008]

In the prior art according to the first method, it is necessary to add a temperature compensating circuit in order to cancel a temperature drift in the reference voltage generating circuit, resulting in an increase in circuit scale. .

In the prior art according to the second method, in order to keep the temperature during operation of the circuit element constant, a heating element or a temperature-sensitive element is placed on a substrate near a circuit to be subjected to a temperature drift reduction. In addition, a temperature control circuit and a temperature control power (power consumption for heating the substrate) are newly required. Further, the reference voltage generating circuit always has a constant current Iz
Flow, there is no fluctuation during operation (generated heat), but the actual cause of the temperature drift is an external factor (variation in the reference voltage generation circuit, etc.) rather than an external factor (fluctuation in other circuits). Temperature fluctuations).

The present invention has been made to solve the above-mentioned conventional problems.

[0011]

According to a semiconductor integrated circuit of the present invention, in a semiconductor integrated circuit having a built-in reference voltage generating circuit, a portion to be reduced in temperature drift of the reference voltage generating circuit is subjected to SOI (Silicon On Insulator).
r) It is characterized by comprising a device.

Further, in the semiconductor integrated circuit according to the present invention,
The OI device is characterized in that the volume occupied by the P-type or N-type semiconductor region constituting the OI device is designed to be a volume maintained at a constant temperature by the operating current of the reference voltage generating circuit.

[0013] According to the semiconductor integrated circuit of the present invention, the characteristics of the SOI device make it less susceptible to external temperature changes, and also provide a heat retention effect due to uniform heating from the inside and a constant amount of heat generated (constant). Therefore, the temperature during operation can be kept stable.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a sectional structural view of a reference voltage generating circuit according to one embodiment of the present invention. As an equivalent circuit, FIG.
Is the same as the circuit shown in FIG.

The constant current section 21 and the constant voltage section 22 may have other structures as long as they have the same operation function. However, in order to simplify the description, a junction gate type FET (constant current section) is used here. 21) and a constant voltage diode (constant voltage section 22).

In the first embodiment, the temperature drift reduction targets are the constant current section 21 and the constant voltage section 2 of the reference voltage generating circuit.
The two are both.

In FIG. 1, a P ⁺ region 11 serving as a gate is provided.
, N region 12 serving as a channel, and N ^{+ serving as} a drain
A junction gate type FET which is a constant current unit 21 is formed by the region 13 and the N ⁺ region 14 serving as a source, and a N ⁺ region 15 serving as a cathode and a P ⁺ region 16 serving as an anode form a constant voltage unit. A constant voltage diode 22 is formed.

An N ⁺ region 14 serving as a source of the constant current unit 21 and an N ⁺ region 15 serving as a cathode of the constant voltage unit 22
Are in direct contact with each other, and the constant current section 21 and the constant voltage section 22
And the volume of the P-type and N-type semiconductor regions (11 to 16) is adjusted so that the temperature of the two portions is maintained at a constant temperature by the operating current Iz. Designed. On top of this, an electrode or FIG.
Conductive film 1 constituting a wiring to be wired like an equivalent circuit of
7 are formed, and the periphery is covered with an insulating film 18.

The heat in the circuit generated by connecting a power supply between the + Vcc electrode N1 and the GND electrode N3 is transmitted through the conductive film 17 which is covered with the insulating film 18 and is in contact therewith. Since the conducted heat conduction is small, heat hardly enters and exits from outside and is diffused into the P-type or N-type semiconductor regions (11 to 16). Further, by the constant current operation, the amount of heat generated in the reference voltage generation circuit is constant, and the volume occupied by the P-type or N-type semiconductor regions (11 to 16) is maintained at a constant temperature by the operation current. , The temperature during operation of the circuit element is stabilized.

However, the volume occupied by the P-type or N-type semiconductor regions (11 to 16) is such that the amount of generated heat and the amount of diffused heat are substantially balanced, and the operating temperature of the SOI device is higher than the ambient temperature but does not exceed the allowable temperature. The reference voltage generating circuit is separated from a portion where a large current changes, and is located at a position on the substrate where temperature fluctuation is small.
Also, the input impedance of the circuit that refers to the reference voltage is high, and it does not affect the reference voltage generation circuit (operating current).

Therefore, the constant current section 2 of the reference voltage generating circuit
1 and the temperature drift of the constant voltage section 22 are reduced, and a stable reference voltage can be generated from the Vref electrode N2.

Next, a second embodiment of the present invention will be described.

FIG. 2 is a sectional structural view of a reference voltage generating circuit according to a second embodiment of the present invention. In terms of an equivalent circuit,
This is the same as the circuit shown in FIG.

The constant current section 21 and the constant voltage section 22 may have other structures as long as they have the same operation function. However, in order to simplify the description, a junction gate type FET (constant current section) is used here. 21) and a constant voltage diode (constant voltage section 22).

In the second embodiment, only the constant voltage section 22 of the reference voltage generating circuit is targeted for temperature drift reduction.

In FIG. 2, P ⁺ region 1 serving as a gate
1 ′, an N region 12 ′ serving as a channel, an N ⁺ region 13 ′ serving as a drain, and an N ⁺ region 14 ′ serving as a source.
A junction gate type FET which is a constant current portion 21 is formed, and an N ⁺ region 15 ′ serving as a cathode and a P ⁺ region 1 serving as an anode are formed.
6 ′ form a constant voltage diode which is the constant voltage section 22.

Further, the N region 12 'serving as a channel and the N ⁺ region 15' serving as a cathode are separated by an insulating film 18 ', and heat conduction performed through a conductive film 17' in contact therewith. Is small, the constant current unit 21 and the constant voltage unit 2
2 does not transfer heat, and the N ⁺ region 15 ′ and the P ⁺ region 16 ′ of the constant voltage unit 22 to be reduced in temperature drift.
Is designed to be kept at a constant temperature by the operating current Iz. Then, a conductive film 17 'for forming an electrode or a wiring for wiring so as to form the equivalent circuit of FIG. 3 is formed thereon, and the periphery thereof is an insulating film 18'.
Because it is covered with heat, there is almost no ingress and egress of heat with the outside.

When a power supply is connected between the + Vcc electrode N1 and the GND electrode N3, the temperature drift of the constant voltage section 22 of the reference voltage generating circuit is reduced for the same reason as in the first embodiment, so that Vref A stable reference voltage can be obtained from the electrode N2.

Although the constant current section 21 shown in FIG. 2 is a dedicated constant current source, it may have no dedicated constant current source and may share a constant current source of another circuit.

[0031]

As described above in detail, in the semiconductor integrated circuit of the present invention, in a semiconductor integrated circuit having a built-in reference voltage generating circuit, a portion of the reference voltage generating circuit to be subjected to temperature drift reduction is SOI (Silicon). On Ins
Further, in the semiconductor integrated circuit according to the present invention, the volume occupied by the P-type or N-type semiconductor region constituting the SOI device is the same as that of the reference voltage generation. The semiconductor integrated circuit of the present invention is characterized in that it is designed to have a volume that is maintained at a constant temperature by the operating current of the circuit. A circuit can be formed, and a reduction in circuit size, size, and power consumption can be achieved.

When the present invention is applied to a reference voltage generating circuit using a conventional temperature compensation method, a reference voltage generating circuit that can obtain a more stable output can be constructed.

[Brief description of the drawings]

FIG. 1 is a sectional structural view of a reference voltage generating circuit according to an embodiment of the present invention.

FIG. 2 is a sectional structural view of a reference voltage generating circuit according to another embodiment of the present invention.

FIG. 3 is a circuit configuration diagram of a general reference voltage generation circuit.

FIG. 4 is a circuit configuration diagram of a reference voltage generation circuit using a temperature compensation circuit.

FIG. 5 is a circuit configuration diagram of another reference voltage generation circuit using a temperature compensation circuit.

FIG. 6 is a diagram provided for explanation of a conventional temperature management method.

FIG. 7 is a diagram provided for explanation of another conventional temperature management method.

[Explanation of symbols]

11, 11 'P ⁺ region (gate) 12, 12' N region (channel) 13, 13 'N ⁺ region (drain) 14, 14' N ⁺ region (source) 15, 15 'N ⁺ region (cathode) 16 , 16 'P ⁺ region (anode) 17, 17' conductive film 18, 18 'insulating film 21 constant current part 22 constant voltage part

Claims (2)

[Claims] In a semiconductor integrated circuit having a built-in reference voltage generation circuit, a portion to be reduced in temperature drift of the reference voltage generation circuit is formed by SOI (Silicon On Insul).
(a) A semiconductor integrated circuit comprising a device. 2. The semiconductor device according to claim 1, wherein a volume occupied by a P-type or N-type semiconductor region constituting said SOI device is designed to be a volume maintained at a constant temperature by an operation current of said reference voltage generation circuit. The semiconductor integrated circuit according to claim 1.