JPS6068414A - Generating circuit of reference voltage - Google Patents

Abstract

PURPOSE:To obtain a generating circuit of reference voltage having high temperature stability by using two MOS elements connected in parallel to each other that have the same conduction type, the same threshold voltage and same size as the 1st or 2nd MOS element which extracts the reference voltage and a bias circuit to constitute a constant current source. CONSTITUTION:A series circuit of a depression type NMOS element 11 and a resistance 13 is connected in parallel to a series circuit of an enhancement type NMOS element 12 and a resistance 14. An end of this series circuit is connected to a battery voltage terminal 2; while the other end is grounded via a parallel circuit of MOS elements 31 and 32. The voltages at junctions between elements 11/12 and resistances 13/14 are connected to an operational amplifier 21. The output of the amplifier 21 is fed back to the gate of the element 12. The elements 31 and 32 have the same conduction type as the elements 11 and 12 together with the same threshold voltage and same size respectively. A constant voltage source 30 supplies the bias voltage to the elements 31 and 32. The gate of the element 11 is grounded. Thus it is possible to obtain the reference voltage having high temperature stability at an output terminal 1 by controlling the size ratio between elements 11 and 12 and the temperature coefficient of the bias voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Investigation] The present invention relates to a reference voltage generation circuit, and particularly to a reference voltage generation circuit capable of obtaining a stable basic mass pressure with respect to veneer reduction.

[Background of the investigation]

As an example of a conventional reference voltage generation circuit, IEEEJou
rhal of 5olid-8tate C1rcu
it, VOI, SC-13, ho, 6. p,
p, 767-774.1) ec, 1978"'C<DB
, A. rANeWN by B1auschild et al.
MO8Tewperature-8table Vol.
The circuit shown in FIG. 1 has been proposed in EfferenceJ.

In the figure, 11 is a depletion/type NMO8 element fi, and 12 is an enhancement type NMO8 element.

The series circuit of the MO8 element 11 and the resistor 13 and the series circuit of the MO8 regulator 12 and the resistor 14 are connected in parallel, one end of which is connected to the -voltage terminal 2, and the other end is connected to the constant-current source 2.
Connected to 0. A fitting point between the resistor 13 and the MO8 resistor 1 l and a connecting point between the resistor 14 and the MO8 resistor 12 are connected to an operational amplifier 21 . The output of the operational amplifier 1 separator 20 is fed back to the MO8 gate 1ZG gate 1C, and is controlled to equalize the drain-to-source voltages of the MOS elements 11 and 12. By making P/S equal! D, MO8 elements 11 and 12
The current flowing through 2 and 2 is made equal. MO8 element 1
By grounding the gate of MO8 element 1, the output terminal connected to the gate of MO8 element 12 can be connected to MO8 elements 11 and 12.
The gate-to-back voltage difference is obtained as the total reference pressure.

By the way, the gate-to-source voltage of the MO8 element is Vt,
The gate capacity (per unit area) is C0 where the threshold voltage (total VthX)
Drain 4 when operating in MO8 regulator 0 saturation region
The flow Id is expressed as the heart. Therefore, the gate-source voltage V z s
becomes .

(3) In Figure 1, the threshold direct pressure of MO8 element 11.12 is Vt+
+H, VthI2, effective 'lk movement ek μt+, μ+2
, the channel length is Lt++Ltt, and the channel width is W.
Let it be W.

Since the current flowing through the MO8 elements ii and 12 becomes unstable, if this current is used as a function, the output reference voltage Vr * f, which is the gate-source voltage difference between the MO8 elements ll and 12, is calculated from equation (2). , Vrer = (Vth, 2-vL hll ). From equation (3), the temperature coefficient of the output standard upper pressure...
(4) It becomes.

Considering the temperature change of the effective mobility μ, the effective mobility dJ
The degree μ can be expressed as an exponential function of the absolute temperature T. Therefore, the effective mobility at temperature T is μ. , when the temperature index of effective mobility is α, the effective #mobility μ is expressed as follows. According to equation (5), temperature coefficient M of effective mobility
In an O8 element, since lattice scattering dominates carrier scattering, the effective #-excitation exponent α is theoretically -1.5.
Even the actual measured value is constant at about -1.5. Therefore, (
Substituting equation (6) into equation (4) yields the output base.

In the reference voltage generation circuit shown in FIG. Determine the size ratio W/L. At this time, the output reference 4 pressure Vr # f and its temperature Vret = (VtbB
Vtmu1. )......(8).

By the way, the threshold voltage difference (Vtb42 VtbH) has a slight temperature coefficient. For example, by implanting phosphorous ions into the channel part of the MO8 element 12 and reducing the threshold voltage of the MO8 element 11, the voltage difference (V=h1z V
tb+t) If k is obtained, the threshold voltage difference (VthI2
VtbH) is 0.5 m V/CCDfMJl
'have. Therefore, the reference voltage Vr*f also has a slight temperature coefficient.

It is necessary to set the size ratio of the MO8 elements 11 and 12, the current flow value 2 of the constant current source 20, and its temperature coefficient.

For this reason, since the constant current 6g20 requires the absolute value of the current and its temperature coefficient, a problem frequently arises in that the circuit configuration becomes complicated.

[Purpose of the invention]

An object of the present invention is to provide a reference voltage generating circuit that can obtain a temperature-stable reference voltage.

[Overview of Brother Mei]

The feature of the present invention is that when an equal direct current is passed through a pair of MO8 elements of the same conductivity type with different threshold voltages, the gate
In the reference voltage generation circuit that generates the source voltage difference as a reference voltage, a pair of MO8 elements are connected to a four-current source that supplies direct current to one of the MO8 elements, and the threshold voltage is equal to one of the two MO8 elements. An embodiment of the present invention will be described with reference to FIG. 2, which is composed of a parallel circuit of two MO8 elements having the same element dimensions, and a bias circuit, fc being less than 16 degrees. 2 in Figure 2, 31.32 is the same conductivity type as MoS cord l12,
Furthermore, the MO8 elements having the same threshold voltage and the same element size are used, and 30 is a constant voltage source that supplies a bias voltage to the MO8 elements 30 and 31. MO8 element 31.32 and redundant pressure [3
0 operates as a constant current source. The stream flowing to MO8 element 31.32 is connected to MO8 element 31.32 and MO8 element 1.
2 is of the same conductivity type, and has the same threshold voltage and element size, MO8 elements 31 and 320) (Iasumi pressure is yb
Then, it can be expressed as from equation (1).

If the impedances of the comb resistors 13 and 14 are equal due to the operation of the operational amplifier 21, the MO8 element ll.

In 12, the DC current of equation (10) flows, and the output reference voltage ■1. ! is (3), (io) formula ↓,...
(11) becomes. In equation (11), due to the second term, μ
, i and μm have the same temperature dependence...(
12) Then, the dimensional specific pressure of the MOB elements 11 and 12 of the differential pair is obtained.

The threshold voltage of Mo5s has a temperature coefficient of about -2 mV/C. Therefore, if the temperature coefficient is one order of magnitude smaller than the temperature coefficient of the threshold voltage of the MO8 element, then by ignoring the bias voltage reduction coefficient, the difference between the pair of M0 becomes
8 elements 11 and 12 are available, making it a temperature stable standard '1
The pressure can be realized with the circuit shown in Figure 2, and the circuit is simple.

FIG. 3 shows another embodiment of the invention. 2 in Figure 3,
The resistors 33, 34 are connected in series, one end is connected to the output terminal 2, the other end is grounded, and the connection point of the resistors 33, 34 is connected to the gate of the MO8 element 31, 32.

The bias voltage of MO8 element 31°32 is the resistance 33.3
9 is obtained by dividing the output component by 4, and the output voltage is composed of resistors 33 and 34. Since the output voltage can be expected to be temperature stable, the bottom pressure of the partial voltage is also Therefore, the IAS circuit can be configured with only two resistors, and the circuit configuration of the reference voltage generation circuit can be simplified.

Bandai Chin 91 Momme In the 3rd box, instead of resistors 1a and 14, a MOS with the gate and drain of MO8 elements connected
Similar results can be obtained using diodes.

Note that 1 in the figure is an input terminal.

[Effect of light cutting]

According to the present invention, since the characteristics of either one of the MO8 elements of the differential pair can match the characteristics of the MO8 element used as a constant current source, a reference voltage that is stable during installation can be obtained.

[Brief explanation of drawings]

FIG. 1 is a conventional circuit diagram of a reference magnetic pressure generation circuit, and FIGS. 2 and 3 are diagrams of a reference voltage generation circuit according to an embodiment of the present invention. 11...depression/type 1vlO8 element, 12,3
1゜32...Enovation type MO8 element, 30.
・・Date No. 1 Mouth No. Z Fig. 3

Claims (1)

[Claims] 1. A second MO8 element having the same conductivity type as the first MO8 element but having a different threshold voltage;
a constant current source that supplies a constant current to the second MO8 element; There is no means for supplying approximately the same current fc* to the second MO8 element. In a reference voltage generation circuit that outputs a gate-source voltage difference of a second MOS gate from an output terminal as a reference voltage, the foot-current source is connected to the first or second M
A reference pressure source characterized by being constructed by connecting two MoS water elements in parallel, which are of the same shape as the O8 element, and have the same threshold pressure and size, and a bias circuit. Raw circuit. 2. The reference voltage generating circuit according to claim 1, wherein the bias circuit is constituted by a voltage dividing circuit for the output voltage.