JP3437274B2 - Reference voltage circuit - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reference voltage circuit used in a semiconductor integrated circuit. In particular, it relates to an improvement in which the temperature characteristic of the reference voltage of the reference voltage circuit is flat and the voltage can be made variable.

[0002]

2. Description of the Related Art A typical example of a reference voltage circuit often used in a semiconductor integrated circuit is shown in FIG.

Referring to FIG. 4, V _CC is a positive voltage source, V _BGR is a bandgap reference voltage, I is a current source, Q ₁₁ ,
Q ₁₂ , Q ₁₃ are NPN transistors, and R ₁₁ , R ₁₂ ,
R ₁₃ is a resistance.

In a current mirror circuit composed of two NPN transistors Q ₁₁ and Q ₁₂ and a resistor R ₁₃ ,
A resistor R ₁₃ connected to the emitter of the transistor Q _12.
The voltage across ΔV _BE is

[0005]

## EQU1 ## ΔV _BE = V _BE (Q ₁₁ ) −V _BE (Q ₁₂ ) where V _BE (Q ₁₁ ) is the base-emitter voltage of the NPN transistor Q ₁₁ , and V _BE (Q ₁₂ ) is the NPN. This is the base-emitter voltage of the transistor Q ₁₂ . Next to
V _BE (Q ₁₁ ) and V _BE (Q ₁₂ ) are respectively

[0006]

[Equation 2] V _BE (Q ₁₁ ) ≈kT · 1n ( _IE (Q ₁₁ ) / I _S ) / q V _BE (Q ₁₂ ) ≈kT · 1n ( _IE (Q ₁₂ ) / I _S ) / q Where k is the Boltzmann constant, T is the absolute temperature, I _E (Q ₁₁ ) is the emitter current of the NPN transistor Q ₁₁ , and I _E (Q ₁₂ ) is the emitter current of the NPN transistor Q ₁₂ . I _S is the saturation current of the junction and q
Is the electron charge. Therefore, the voltage across resistor R ₁₃ is ΔV _BE

[0007]

## EQU3 ## ΔV _BE = kT1n ( _IE (Q ₁₁ ) / _IE (Q ₁₂ )) / q (Equation 1) The bandgap reference voltage V _BGR is

[0008]

## EQU4 ## V _BGR = V _BE (Q ₁₃ ) + R ₁₂ · I ₁₂ , and the current I ₁₂ is almost close to the emitter current I _E (Q ₁₂ ).

[0009]

Equation 5] Since denoted _{I 12 ≒ I E (Q 12} ) = ΔV BE / R 13, the bandgap reference voltage V _BGR,

[0010]

[Equation 6] V _BGR = V _BE (Q ₁₃ ) + ΔV _BE · R ₁₂ / R ₁₃ (Equation 2) As is well known, the base-emitter voltage V _BE (Q ₁₃ ) of a transistor has a negative temperature coefficient, and ΔV _BE has a positive temperature coefficient because it is proportional to the absolute temperature T from (Equation 1). Therefore, the voltage V _BGR having a flat temperature characteristic can be obtained by selecting the ratio of R ₁₂ and R ₁₃ .

[0011]

By the way, in the conventional reference voltage circuit shown in FIG. 4, the voltage V _BGR is
By (Equation 2), it is regulated to about 1.2 V, and it is difficult to set it to a free value.

An object of the present invention is to solve this problem, and it is an object of the present invention to provide a reference voltage circuit having a flat temperature characteristic and capable of setting a reference voltage to a free value.

[0013]

The above object is to provide a first NPN transistor having an emitter connected to a first power supply and a second NPN transistor having an emitter connected to a first power supply through a first resistor. A first current mirror circuit having an NPN transistor, and a fifth NPN transistor having at least one forward-connected PN junction ;
A third NPN transistor having data is connected to the first power supply through a fifth NPN transistor, the emitter and the second
And a fourth NPN transistors through a resistor connected to the first power supply and a second current mirror circuit having the collector and the fourth NP of the second NPN transistor
The collector of the N transistor is connected to the second via the third resistor.
Connected to the power supply of the first NPN transistor and the fifth
Also connected to the first power supply by a reference power supply circuit in which the NPN transistor and the NPN transistor are formed independently of each other .
A first power source through a first transistor and a first resistor;
A first transistor having a second transistor connected to
Karen to obtain a voltage drop with a positive temperature coefficient from
Mirror circuit and a fifth NPN diode-connected transistor
The first power supply via the transistor and the fifth transistor
Via a third transistor connected to the
And a fourth transistor connected to the first power supply.
And obtain a voltage drop with a negative temperature coefficient from the second resistor.
And a second current mirror circuit
The collector of the transistor and the collector of the fourth transistor are
Connected to the second power supply through a resistor of 3
The transistor and the fifth transistor are formed independently of each other.
Is also achieved by the reference power supply circuit .

According to the above technical idea, the emitter is the first
A first NPN transistor connected to the power supply of the
Is connected to the first power supply via the first resistor.
A first current having a second NPN transistor
The mirror circuit and the first NPN transistor whose emitter is
A third NP connected to the first power supply via a
The N-transistor and the emitter are connected through the second resistor to
A fourth NPN transistor connected to the first power supply of
And a second current mirror circuit having
2 NPN transistor collector and the fourth NP
The collector of the N transistor is connected to the second via the third resistor.
Reference voltage circuit connected to the power supply of
A first PNP transistor having a power supply connected to a first power supply
And the emitter is connected to the first power source through the first resistor.
A first PNP transistor with a second PNP transistor connected
The current mirror circuit and the emitter via the first resistor
A second PNP transistor connected to said first power supply
And a first current mirror circuit having
Via the first PNP transistor, the first
A third NPN transistor connected to the power supply and an emitter
Is connected to the first power supply via a second resistor
A second current source having a fourth PNP transistor
Of the second PNP transistor
Collector and collector of the fourth PNP transistor
And are connected to a second power supply via a third resistor
It can be realized as a quasi-voltage circuit.

The above technical idea is further applied to the first power source.
Via the first transistor connected and the first resistor
A second transistor connected to the first power supply,
Having a positive temperature coefficient from the first resistor.
And a first current mirror circuit for obtaining
Through a third transistor connected to the source and a second resistor
And a fourth transistor connected to the first power supply
And having a negative temperature coefficient from this second resistance.
A fourth current mirror circuit for obtaining a pressure drop,
The second transistor of and the fourth transistor of
A reference voltage connected to the second power source through the third resistor.
It can also be realized as a pressure circuit.

[0016]

The reference voltage circuit according to the present invention has two current mirror circuits, the first NPN transistor Q ₁ and the second NPN transistor Q ₁ .
The first current mirror circuit including the NPN transistor Q ₂ and the first resistor R ₁ has the same configuration as the current mirror circuit shown in FIG. Therefore, the second NP
The current I ₂ flowing through the collector of the N-transistor Q ₂ is

[0017]

[Equation 7] _{I 2 ≒ I E (Q 2} ) = (V BE (Q 1) -V
_BE (Q ₂ )) / R ₁ and two base-emitter voltages V _BE (Q ₁ ) and V
_{What is BE} (Q ₂ )

[0018]

V _BE (Q ₁ ) ≈kT · 1n ( _IE (Q ₁ ) / _IS ) / q V _BE (Q ₂ ) ≈kT · 1n ( _IE (Q ₂ ) / I _S ) / q Is expressed as

[0019]

I ₂ = kT · 1n ( _IE (Q ₁ ) / _IE (Q ₂ )) / q · R ₁ (Equation 3)

The third NPN transistor Q₃When
Fourth NPN transistor Q_FourAnd the second resistance R₂And few
At least one PN junction Q_FiveThe second current instrument consisting of
The error circuit is different from the current mirror circuit shown in FIG.
At least one PN junction Q _FiveIs the third NPN transition
Star Q₃Is connected in the forward direction between the emitter of the
The only difference is that. Therefore, the fourth NPN transition
Star Q_FourCurrent I flowing in the collector of_FourIs

[0021]

[Number 10] _{I 4 ≒ I E (Q 4} ) = (V BE (Q 3) + nV
_BE (Q ₅ ) −V _BE (Q ₄ )) / R ₂ where n is the number of PN junctions Q ₅ and n ≧ 1.
Becomes Base-emitter voltage V _BE (Q ₃ ) and V _BE (Q
₅ ) and V _BE (Q ₄ ) have a proportional relationship,

[0022]

I ₄ = mV _BE (Q ₅ ) / R ₂ (Equation 4) where m is a constant. Becomes

In the reference voltage circuit according to the present invention, the second N
The collector current I ₂ of the PN transistor Q ₂ and the fourth NP
N and the collector current I ₄ of the transistor Q ₄ are both flowing through the third resistor R _{3. Assuming} that the voltage drop caused by flowing through the third resistor R ₃ is V _BGR , this voltage V _BGR is

[0024]

[Formula 12] V _BGR = R ₃ (I ₂ + I ₄ ), and the currents I ₂ and I ₄ are given by (Equation 3) and (Equation 4).

[0025]

[ _Expression 13] V _BGR = R ₃ (kT · 1n ( _IE (Q ₁ ) / _IE (Q ₂ )) / q · R ₁ + mV _BE (Q ₅ ) / R ₂ ) (Equation 5 ). In (Equation 5), the first term has a positive temperature coefficient because it is proportional to the absolute temperature T, and the second term has a negative temperature coefficient. Therefore, by selecting the ratio of R ₁ and R ₂ , the temperature coefficient can be brought close to 0, and the reference voltage V with a flat temperature characteristic can be obtained.
You can get _BGR . Further, the reference voltage V _BGR is
As can be seen from (Equation 5), the value can be freely changed by changing the third resistance R ₃ .

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The reference voltage circuit according to the present invention will be described in more detail below with reference to the drawings.

First Embodiment (corresponding to claim 1) Refer to FIG. 1. FIG. 1 is a circuit diagram of a reference voltage circuit according to a first embodiment of the present invention. In FIG. 1, Q ₁ , Q ₂ , Q _3, and Q ₄ are first to fourth NPN transistors, respectively, and Q ₅
Is a PN junction including an NPN transistor whose collector and base are short-circuited, and R ₁ , R ₂ , R ₃ , R _4, and R ₅ are first to fifth resistors, respectively. Although the number of the PN junction Q ₅ is one in FIG. 1, a plurality of PN junctions Q ₅ may be connected in series.

First NPN transistor Q₁The emitter of
Is directly grounded, the collector and base are shorted, and
And the second NPN transistor Q₂Connected to the base of
ing. Second NPN transistor Q₂The emitter of is
1 resistance R₁It is grounded (GND) through
Third resistance R₃Power through V_CCIt is connected to the. First
1 NPN transistor Q₁And the second NPN Transis
Q₂And the first resistance R ₁With the first current mirror
The circuit is configured. The first NPN transistor
Q₁Is the fourth resistor R_FourPower through V_CCTo
It is connected.

Third NPN transistor Q₃The emitter of
Is the PN junction Q_FiveGrounded through the collector and base
Are short-circuited with the fourth NPN transistor Q_Four
Connected to the base of. Fourth NPN transistor
Q_FourThe emitter of the second resistor R₂Grounded through
The inductor is the second NPN transistor Q₂Contact the collector of
Has been continued. Third NPN transistor Q₃And the fourth
NPN transistor Q _FourAnd PN junction Q_FiveAnd the second resistance R
₂Constitutes a second current mirror circuit
It The third NPN transistor Q₃Collector of
Fifth resistor R_FivePower through V_CCIt is connected to the.

As described above, the current I ₂ flowing through the collector of the _second NPN transistor Q ₂ is

[0031]

[Equation 14] I ₂ = kT · 1n ( _IE (Q ₁ ) / _IE (Q ₂ )) / q · R ₁ (Equation 3), and the collector of the _fourth NPN transistor Q ₄ The current I ₄ flowing through the pn junction Q ₅ is one,
Since m = 1 in (Equation 4)

[0032]

## EQU15 ## I ₄ = V _BE (Q ₅ ) / R ₂ ... (Equation 4A) Then, since the third resistor R ₃ collector current I ₂ and the collector current I ₄ and flows both when the third voltage across the resistor R ₃ and the reference voltage V _BGR, the reference voltage V _BGR is

[0033]

[ _Formula 16] V _BGR = R ₃ (kT · 1n ( _IE (Q ₁ ) / _IE (Q ₂ )) / q · R ₁ + V _BE (Q ₅ ) / R ₂ ) (Equation 5A ). In this (Equation 5A), the first term has a positive temperature coefficient because it is proportional to the absolute temperature T, and the second term has a negative temperature coefficient, so that the emitter resistance R _{1 of the second} NPN transistor Q ₂ is The temperature coefficient can be brought close to 0 by selecting the ratio of the fourth NPN transistor Q _{4 to} the emitter resistance R ₂ . And the reference voltage V
_{The value of BGR} can be freely changed by changing the third resistance R ₃ .

Second Embodiment (corresponding to claim 2) See FIG. 2. FIG. 2 is a circuit diagram of a reference voltage circuit according to a second embodiment of the present invention. In FIG. 2, the PN junction Q ₅ and the first NPN transistor Q ₁ are integrated, and the collector current of the _first NPN transistor Q ₁ supplied via the resistor R ₁ is changed to the second NPN transistor Q ₂ It is only different in that it is supplied from its emitter via. Therefore, the equation for giving the reference voltage V _BGR does not change in (Equation 5A), and it is possible to obtain the reference voltage V _BGR with a flat temperature characteristic and a freely selectable voltage value.

Third Embodiment (corresponding to claim 3) See FIG. 3. FIG. 3 is a circuit diagram of a reference voltage circuit according to a third embodiment of the present invention. In FIG. 2 of the second embodiment, the NPN transistors Q ₁ , Q ₂ , Q _3, and Q ₄ are all PNP transistors Q ₂₁ , Q ₂₂ , Q _23, and Q _{24 of} opposite conductivity type, and the polarities of the power sources are set at the same time. It has been inverted. The operation and the characteristics of the reference voltage are the same as those in the third embodiment.

[0036]

As described above, in the reference power supply circuit according to the present invention, the first power supply whose emitter is connected to the first power supply is used.
NPN transistor and emitter via the first resistor
A second NPN transistor connected to the first power supply
A first current mirror circuit having at least one
Fifth NPN tiger with forward-connected PN junction
Transistor and emitter through the fifth NPN transistor
And a third NPN transistor connected to the first power supply
And the emitter is connected to the first power supply through the second resistor.
Second curren having a fourth NPN transistor
And a mirror circuit of the second NPN transistor.
And the collector of the fourth NPN transistor is the third
Connected to the second power supply through the resistor of
The transistor and the fifth NPN transistor are independent of each other.
To the reference power supply circuit or the first power supply
Via the connected first transistor and the first resistor
A second transistor connected to the first power supply,
Obtaining a voltage drop having a positive temperature coefficient from the first resistor,
No. 1 current mirror circuit and diode-connected fifth
Via the NPN transistor and the fifth transistor
A third transistor connected to the first power supply and a second transistor
A fourth transistor connected to the first power supply through a resistor
And a voltage having a negative temperature coefficient from the second resistance
A second current mirror circuit for obtaining a drop,
The collector of the transistor and the collector of the fourth transistor
Is connected to a second power source via a third resistor,
Transistor and the fifth transistor are independent of each other
Since it is formed as a reference power supply circuit, the temperature characteristic is flattened by selecting the ratio of the two emitter resistors, and the value of the reference voltage can be set freely by changing the value of the resistor in the collector circuit. Can be changed. Furthermore
In the former, "the first NPN transistor and the first NPN transistor
And the NPN transistor 5 are formed independently of each other.
The effect of "
Transistor and the fifth transistor are independent of each other
The effect of being formed is that the first current
Characteristics of the first NPN transistor and the second
Features of the fifth NPN transistor in the current mirror circuit
Since it is possible to control the sex independently of each other,
In (Equation 5A), the first current mirror circuit is
Positive temperature coefficient of the first term and second current mirror circuit
The negative temperature coefficient of the second term based on
Thus, it becomes possible to precisely control the circuit characteristics. So
As a result, the temperature dependence of the reference voltage can be improved for the entire circuit.
Unique effect of being able to approach zero (0) completely
You can play the fruit. Just as in the latter
Is a first transistor in the first current mirror circuit
Characteristics and the fifth transition in the second current mirror circuit
It is possible to control the characteristics independently of each other.
Therefore, in (Formula 5A) described in this specification, the first
Positive temperature coefficient of the first term based on the current mirror circuit of
And the negative temperature of the second term based on the second current mirror circuit
The circuit characteristics are precisely controlled so that the frequency coefficient and the frequency coefficient cancel each other out.
It becomes possible to control. As a result, in the former,
For the circuit as a whole, the temperature dependence of the reference voltage is reduced to zero (0).
The unique effect of being close to
You can Similarly, in the latter case, the circuit
As a body, the temperature dependence of the reference voltage becomes closer to zero (0).
It has the unique effect of being able to kick
It

[Brief description of drawings]

FIG. 1 is a circuit diagram of a reference voltage circuit according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram of a reference voltage circuit according to a second embodiment of the present invention.

FIG. 3 is a circuit diagram of a reference voltage circuit according to a third embodiment of the present invention.

FIG. 4 is a circuit diagram of a reference voltage circuit according to a conventional technique.

[Explanation of symbols]

Q ₁ first NPN transistor Q ₂ second NPN transistor Q ₃ third NPN transistor Q ₄ fourth NPN transistor Q ₅ PN junction Q ₁₁ , Q ₁₂ , Q ₁₃ , NPN transistor R ₁ first resistor R ₂ Second resistor R ₃ Third resistor R ₄ , R ₅ Resistors R ₁₁ , R ₁₂ , R ₁₃ Resistor V _CC Positive voltage source V _BGR Bandgap reference voltage I Current sources I ₂ , I ₄ Collector current

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G05F 3/30

Claims (2)

(57) [Claims] 1. A first having an emitter connected to the first power supply
And NPN transistors, PN emitter, which is connected to the first current mirror circuit and a second NPN transistor connected to said via a first resistor first power source, at least one forward Have a bond
A fifth NPN transistor and the emitter of the fifth NPN transistor
A <br/> third NPN transistor connected to said first power supply through a PN transistor and a fourth NPN transistor having an emitter connected to said first power supply through a second resistor having a second current mirror circuit, the collector of the second NPN transistor and the collector of the fourth NPN transistor is connected to the second power supply through the third resistor, the first NPN Transistor and the fifth NPN transistor
A reference power supply circuit characterized in that it is formed independently of each other . 2. A first transistor connected to a first power supply, and a first transistor connected to the first power supply via a first resistor.
Second and a transistor, a first current mirror circuit to obtain the voltage drop with a positive temperature coefficient from said first resistor, and a fifth transistor which is diode-connected, the fifth
It has a third transistor connected to said first power supply through the transistor, and a fourth transistor connected to said via a second resistor first power source, the second
Second current mirror circuit that obtains a voltage drop having a negative temperature coefficient from the resistance of the second transistor, the collector of the second transistor and the collector of the fourth transistor are connected to the second resistor via the third resistor. The first transistor and the fifth transistor are connected to a power supply and
A reference power supply circuit characterized by being formed independently of each other .