JPH0560128B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to semiconductor integrated circuits, and particularly to analog integrated circuits.
This invention relates to a reference voltage generation circuit used as a constant voltage source in an IC circuit.

[Conventional technology]

As is already known, reference voltage generation circuits are broadly divided into methods using avalanche breakdown diodes and methods using band gear preference using energy bands within semiconductors. The purpose of both methods is to improve the temperature dependence of the generated reference voltage, but here a reference voltage generating circuit using the latter method will be outlined with reference to FIG. The circuit shown in FIG. 3 is basically a reference voltage generating circuit that utilizes the energy band between the base and emitter of a transistor, and the generated reference voltage V _ref can be expressed by the following relational expression. That is, V _ref = (R ₃ + R ₄ + R ₅ )・(V _B1 − V _B2 ) /R ₄ +V _BEQ5 …(1) = (R ₃ +R ₄ +R ₅ )・V _T・_lo (N) /R ₄ +V _BEQ5 …(2) Here, V _B1 and V _B2 are transistors Q ₃ and
The base potential of Q ₄ , V _BEQ5 is the base-emitter potential of transistor Q ₅ , V _T is a constant expressed as kT/q, k is Boltzmann's constant, T is absolute temperature, q is electric charge, and ln (N) is This is the natural logarithm of the emitter ratio N of transistors Q ₃ and Q ₄ .

The V _BE of transistor Q ₅ has a negative temperature coefficient due to the base-emitter junction, while each resistor R ₃ ,
R ₄ and R ₅ have positive temperature coefficients, and V _T also has temperature dependence. Therefore, the reference voltage V _ref is given by the above formula
Temperature compensation is performed by appropriately selecting each resistor in (1) and (2) and the emitter ratio of transistors Q ₃ and Q ₄ . In this case, transistor Q ₁ ,
Q ₂ and resistors R ₁ and R ₂ constitute a constant current circuit, R ₁ = R ₂ , and the currents I ₁ and I ₂ flowing through this are in a current mirror configuration, so they are matched. When there is, I ₁ = I ₂ . Further, the emitter ratio is the emitter area ratio of a transistor, but it can be equivalently replaced with the ratio of the number of transistors arranged in parallel.

[Problem that the invention seeks to solve]

In the above configuration, transistors Q ₁ and Q ₂
Equal current is supplied to transistors Q ₃ and Q ₄ by a constant current source, but if the consistency of the constant current source deviates due to some factor, that is, I ₁ ≠
In the case of I ₂ , a change in the current value supplied to Q ₃ and Q ₄ appears as a change in the respective base potentials V _B1 and V _B2 , causing a change in the reference voltage V _ref . in this case,
The factors that cause mismatch exist in the elements themselves that make up the circuit, and when integrated into an IC, PNP transistors
Characteristics vary widely compared to NPN transistors.
In pattern design, variations in characteristics due to wiring length, variations in manufacturing process, etc. are considered, and these cause mismatch in the constant current circuit and cause fluctuations in the reference voltage V _ref .

[Means and actions for solving problems]

An object of the present invention is to provide _a reference voltage generation circuit which solves the above-mentioned problems _.
a first transistor Q ₃ connected to a common contact with constant current sources Q ₇ and J, and whose base is connected to the reference voltage generation terminal via a third resistor R ₃ ;
The collector is connected to the common contact via the resistor _R2 , and the base is connected to the third resistor and the fourth resistor R4 _.
a second transistor Q ₄ connected to the reference voltage generation terminal via a fifth resistor Q4, and a fifth resistor connected to a common contact between the base of the second transistor and the fourth resistor.
a third transistor Q ₅ whose collector is connected to the base and whose emitter is grounded via R ₅ ; whose base is commonly connected to the collector of the first transistor and whose emitters are A fourth transistor _Q6 has a collector connected to the constant current source, a collector connected to the constant current source, a base connected to the collector of the second transistor, and an emitter connected to the fourth transistor Q6. a fifth transistor _Q10 that is grounded, and a base potential _VB1 of the first transistor;
and the base potential V _B2 of the second transistor is the product of the collector potentials V _C1 , V _C2 of the first transistor and the second transistor, and the reciprocals of the voltage gains A _Q3 , A _Q4 (V _B1 = V It is characterized in that it is set by _C1 /A _Q3 and V _B2 =V _C2 /A _Q4 .

〔Example〕

FIG. 1 is a circuit diagram of an embodiment of a reference voltage generating circuit according to the present invention. As is clear from Figure 1,
The transistor Q ₁ that constituted the conventional constant current source,
Q ₂ , transistor Q ₈ , transistor Q ₉ are removed and instead the collector of the transistor Q ₃ as the first transistor and the base of the resistor R ₁ and the transistor Q ₆ as the fourth transistor, and as the second transistor The collector of the transistor Q ₄ is connected to the resistor R ₂ and the base of the transistor Q ₁₀ as the fifth transistor. Further, the resistor R ₁ =R ₂ , the reference voltage V _ref is generated from the reference voltage generation terminal V _ref (same reference symbol for convenience), and the transistor Q ₅ and the third, fourth, and third transistors are used as the third transistor. 5 resistances R ₃ , R ₄ , R ₅
is the same as before.

In such a configuration, transistors Q ₃ ,
Let the collector potentials of Q ₄ be V _C1 and V _C2 , respectively, and the currents flowing through the first and second resistors R ₁ and R ₂ as I ₁ and I _2, respectively.
Then, the respective voltage gains A _Q3 and A _Q4 can be expressed as follows due to the amplification effect of the transistors Q ₃ and _{Q 4} . That is, A _Q3 = ΔV _C1 / ΔV _B1 = R ₁ / γe1 …(3) A _Q4 = ΔV _C2 / ΔV _B2 = R ₂ / γe2 … (4) Here, γe1 and γe2 are transistors Q ₃ and Q ₄ respectively.
The emitter resistance is γe1=V _T /I ₁ , γe2=
V _T /I ₂ .

As is clear from equations (3) and (4), the transistor
The base potentials V _B1 and V _B2 of Q ₃ and Q ₄ are 1/A _Q3 and 1/A _Q4 of V _C1 and V _C2 , respectively. Therefore, as mentioned above, even if the current I ₁ ≠ I ₂ occurs due to some factor,
The errors given to V _B1 and V _B2 are (1/
A _Q3 ) times and (1/A _Q4 ) times, and it can be seen that the influence is extremely small. The reference voltage V _ref depends largely on the values of V _B1 and V _B2 as shown in equation (1), but
With such a circuit configuration, the influence of V _B1 and V _B2 on fluctuations in I ₁ and I ₂ can be made extremely small, and as a result, the reference voltage V _ref can be stabilized. In the conventional circuit shown in FIG. 3, since transistors Q ₃ and Q ₄ have no amplifying effect, I ₁ ,
Fluctuations in I ₂ directly appear in V _B1 and V _B2 , causing fluctuations in the reference voltage V _ref . In the present invention, the transistor Q ₃ ,
The larger the gain of Q ₄ or the resistor R ₁ ,
If you use a value larger than R ₂ , then naturally V _B1 ,
Fluctuations in V _B2 can be suppressed to a smaller level.
Note that the transistors Q ₇ and J are constant current sources that make the power supply V _cc a constant current.

FIG. 2 is a circuit diagram of another embodiment of the reference voltage generating circuit according to the present invention. This circuit does not have a power supply terminal _Vcc due to its circuit configuration, and receives current from the power supply through an external resistor R. In this case, transistors Q ₈ , Q ₉ and transistors Q ₁₀ ,
Configure a constant current circuit with _Q11 , and
The effects of Q ₃ , Q ₄ etc. are the same as in the first embodiment.
As is clear from the figure, in the circuit of Figure 1, V _ref , V _cc ,
Three terminals for GND were required, but in this circuit
It has two terminals, V _ref and GND, which can simplify the circuit.

〔Effect of the invention〕

According to the present invention, even if a mismatch occurs due to some factor, temperature compensation can be reliably performed, and a reference voltage generation circuit with less temperature dependence can be provided.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of one embodiment of the reference voltage generation circuit according to the present invention, FIG. 2 is a circuit diagram of another embodiment of the reference voltage generation circuit according to the present invention, and FIG. 3 is a conventional reference voltage generation circuit. It is. Explanation of symbols, Q ₁ ~ Q ₁₁ ...Transistor, R ₁ ~
R ₆ ...Resistor, V _ref ...Reference voltage generation terminal, V _cc ...
...Power supply voltage terminal.

Claims (1)

[Claims] 1 The collector is connected to _the common contact between the reference voltage generation terminal V ref and the constant current sources Q ₇ and J through the first resistor R 1 , and the base is connected through the third resistor R ₃ to the common contact between the reference voltage generation terminal V _ref and the constant current sources Q 7 and J. a first transistor connected to the reference voltage generation terminal;
Q ₃ and a second resistor whose collector is connected to the common contact via a second resistor R ₂ and whose base is connected to the reference voltage generation terminal via the third resistor and fourth resistor R ₄ . a third transistor Q ₄ whose collector is connected to the base via a fifth resistor R ₅ to a common contact between the base of the second transistor and the fourth resistor, and whose emitter is grounded.
a fourth transistor Q ₆ whose base is commonly connected to the collector of the first transistor, _whose collectors are connected to the emitters of the first and second transistors, and whose emitter is grounded. and a fifth transistor _Q10 whose collector is connected to the constant current source, whose base is connected to the collector of the second transistor, and whose emitter is grounded, _The base potential V _B1 and _the base potential V _B2 of the second transistor are _the product ₍ A reference voltage generation circuit characterized in that the reference voltage generation circuit is set by V _B1 = V _C1 /A _Q3 , V _B2 = V _C2 /A _Q4 ).