JP2010277479A - Power circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power circuit for supplying temperature-compensated constant voltage and constant current. <P>SOLUTION: The power circuit includes: a first reference voltage source which has a first constant current source for receiving voltages from the outside by both ends to output a current having a positive temperature coefficient and outputs a first voltage having a zero temperature coefficient; a first diode circuit which has one end connected to the first constant current source; a first resistance which has one end connected to the other end of the first diode circuit and has such a resistance value set thereto that fluctuation of a voltage generated between both ends due to temperature has the same magnitude as the fluctuation of the voltage generated between both ends of the first diode circuit due to temperature and has a sign opposite to that of this fluctuation; a second reference voltage source which is connected to the other end of the first resistance and outputs a second voltage; and a reference current source which receives the first voltage to output a constant current having a zero temperature coefficient. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a power supply circuit, and more particularly to a power supply circuit capable of temperature compensation.

  In many devices, semiconductor devices mounted with electronic circuits that realize various functions are used. In such a semiconductor device, a power supply circuit such as a current source or a voltage source is used. In addition, a temperature-compensated current source or voltage source that supplies a constant current or voltage with respect to changes in ambient temperature may be used. For example, there is a case where a high voltage power source necessary for signal input / output with the outside is input from the outside and the internal operation is performed with a low voltage compensated for temperature.

A bandgap reference voltage source and a wideler circuit are known as temperature compensated voltage sources. A power supply circuit that amplifies the output of these voltage sources to a necessary constant voltage by an amplifier is known. Furthermore, a bandgap reference circuit that obtains a constant voltage that is an integral multiple of the bandgap reference voltage source has been proposed (see, for example, Patent Document 1).
Conventionally, a current source and a voltage source are often proposed as separate circuits.

JP 2000-284845 A

  The present invention provides a power supply circuit that supplies a constant voltage and a constant current capable of temperature compensation.

  According to one aspect of the present invention, there is provided a first constant current source that outputs a current having a positive temperature coefficient by inputting a voltage to both ends from the outside, and outputs a first voltage having a zero temperature coefficient. 1 reference voltage source, a first diode circuit having one end connected to the first constant current source, and one end connected to the other end of the first diode circuit. A first resistor whose resistance value is set to be equal in magnitude and opposite in sign to the fluctuation due to the temperature of the voltage generated at both ends of the first diode circuit, and the other of the first resistor. A second reference voltage source that is connected to the end and outputs a second voltage; and a reference current source that inputs the first voltage and outputs a constant current having a temperature coefficient of zero. A power supply circuit is provided.

  According to another aspect of the present invention, a first reference voltage source that inputs a voltage from the outside to both ends and outputs a first voltage having a temperature coefficient of zero, and the first reference voltage source A first diode circuit whose one end is connected to the input terminal on the low voltage side and an absolute value is connected between the other end of the first diode circuit and the ground, and a variation due to the temperature of the voltage generated at both ends is detected. A first resistor having a resistance value set so that the magnitude and the magnitude of the voltage variation at both ends of the first diode circuit are equal and opposite in sign, and the first voltage are input. And a reference current source that outputs a constant current.

  According to the present invention, a power supply circuit that supplies a constant voltage and a constant current capable of temperature compensation is provided.

1 is a circuit diagram illustrating the configuration of a power supply circuit according to an embodiment of the invention. It is a circuit diagram of the power supply circuit of a comparative example. FIG. 3 is a graph showing simulation data of an external power supply noise blocking property of the power supply circuit shown in FIG. 2. FIG. 2 is a graph showing simulation data of a cutoff characteristic of external power supply noise of the power supply circuit shown in FIG. 1. It is a circuit diagram which illustrates the composition of the power circuit concerning other embodiments of the present invention. It is a circuit diagram which illustrates the composition of the power circuit concerning other embodiments of the present invention. It is a circuit diagram which illustrates the composition of the power circuit concerning other embodiments of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Note that, in the present specification and each drawing, the same elements as those described above with reference to the previous drawings are denoted by the same reference numerals, and detailed description thereof is omitted as appropriate. In the present specification, the temperature coefficient of current is the temperature coefficient of the absolute value of current regardless of the direction of current flow, and the temperature coefficient of voltage is the temperature coefficient of the absolute value of voltage.

(First embodiment)
FIG. 1 is a circuit diagram illustrating the configuration of a power supply circuit according to an embodiment of the invention.
As shown in FIG. 1, the power supply circuit 60a of the present embodiment includes a first reference voltage source 30, a first diode circuit 10a, a first resistor R20, a transistor Q11 (reference current source), and a transistor Q12 (first current). 2 reference voltage sources), a transistor Q13, and a resistor R11.

The power supply circuit 60a is a power supply circuit that supplies a power supply Vcc from the outside and outputs a constant voltage and a constant current that are temperature compensated to zero to the output terminals Vout and Iout, respectively.
For example, a high voltage power supply Vcc is supplied from the outside to drive a power transistor, power MOSFET, and IGBT, and a constant voltage V ₂ (second voltage) and a constant current I ₀ lower than the power supply Vcc are output to the output terminals Vout and Iout, respectively. It can be used for a power supply circuit that outputs to

In addition, for example, Bi-CMOS is used, and the power supply Vcc = 15 to 30V supplied from the outside is used as the power supply of the output circuit configured with bipolar, and the low constant voltage V ₂ = 3.3 to 5V is configured with CMOS. It can be used as a power source for circuits.

In the present embodiment, the case where a band gap reference voltage source known as a high-accuracy power source having a temperature coefficient compensated to zero is used as the first reference voltage source 30 is illustrated. In the present embodiment, as will be described later, the first reference voltage source 30 includes a first constant current source 40 having a positive temperature coefficient.
In addition, as the first diode circuit 10a, a configuration in which three first transistors 11a to 11c each having a base and a collector are connected in series is illustrated.
Further, the case where transistors are respectively used as the reference current source Q11 and the second reference voltage source Q12 is illustrated.
First, each part will be described.

The first reference voltage source 30 in this embodiment is a Wideler type bandgap reference voltage source, and includes a current composed of NPN transistors Q31, Q32, Q34, Q37, resistors R31, R32, R33, and PNP transistors Q35 and Q36. Has a mirror.
Here, the emitter areas of the transistors Q32 and Q34 are 4 times and 2 times the emitter area of the transistor Q31, respectively. The emitter areas of all other transistors Q35 to Q37, Q11 to Q13, and 11a to 11c are equal to the emitter area of the transistor Q31.

Resistors R31 and R32 are connected to the collectors of the transistors Q31 and Q32, respectively. The other ends of the resistors R31, R32 are connected to each other, the potential of the connection point Vo1, as described later, the first voltages V ₁ which is temperature compensated.
The emitter of the transistor Q31 is connected to the ground GND, and the emitter of the transistor Q32 is connected to the ground GND via a resistor R33. The base and collector of the transistor Q31 and the base of the transistor Q32 are connected to each other. As will be described later, the transistors Q31 and Q32 constitute a first constant current source 40 that supplies current I to the resistors R31 and R32.

The base of the transistor Q34 is connected to the collector of the transistor Q32, and the emitter of the transistor Q34 is connected to the ground GND.
The PNP transistors Q35 and Q36 constitute a current mirror, and each emitter is connected to the power supply Vcc.
The collector of the transistor Q37 is connected to the collector of the transistor Q36 on the reference side of the current mirror, and the base of the transistor Q37 is connected to the collector of the transistor Q35 and the collector of the transistor Q34.

Here, the emitter of the transistor Q37 is defined as a connection point Vo3.
When the connection point Vo3 and the connection point Vo1 are connected, it becomes a Wideler type band gap reference voltage source, and a constant current 2I having a positive temperature coefficient flows through the branches of the connection points Vo3 and Vo1, as will be described later.

In this embodiment, the collector and base of the transistor Q13 and the base of the transistor Q12 (second voltage source circuit) are connected to the connection point Vo3.
The collector of the transistor Q12 is connected to the power supply Vcc, the emitter to the output terminal Vout of the second voltage _{V 2.} Incidentally, the transistor Q13 is connected to the connection point Vo3, the voltage of the output terminal Vout is to equal the second voltage V _2.

In the present embodiment, the first diode circuit 10a and the first resistor R20 are inserted in series between the connection points Vo3 and Vo1 via the transistor Q13.
The first diode circuit 10a has a configuration in which three first transistors 11a to 11c each having a base and a collector are connected in series.

Further, the base of the transistor Q11 (reference current source) is connected to the collector of the first transistor 11a and the emitter of the first transistor 11b of the first diode circuit 10a. The emitter of the transistor Q11 (reference current source) is connected via a resistor R11 to the ground GND, the collector outputs a constant current _{I 0} to the terminal Iout (inhaling).

The base of the transistor Q11 (reference current source) is connected to the collector of the first transistor 11a of the first diode circuit 10a because the emitter voltage of the transistor Q11 (reference current source) is the first voltage. it is to equal to V _1. As will be described later, since the temperature coefficient of the first voltage V ₁ is zero-compensated, the constant current I ₀ output from the collector of the transistor Q11 (reference current source) is also temperature-compensated to zero temperature coefficient. .

Next, the operation of the power supply circuit 60a of this embodiment will be described. Note that the base current of the transistor is ignored.
Assuming that the currents flowing through the resistors R31 and R32 are I ₁ and I ₂ respectively, the current 2I flowing in the branch between the connection points Vo3 and Vo1 is given by the equation (1-1).

2I = I ₁ + I ₂ ... (1-1)

Further, if the base-emitter voltages of the transistors Q31, Q32, and Q33 are Vbe, Vbe2, and Vbe3, respectively, equations (1-2) to (1-4) are established.

V ₁ = Vbe + I ₁ × R31 (1-2)
V ₁ = Vbe3 + I ₂ × R32 (1-3)
_{Vbe = Vbe2 + I 2 × R33} ·· (1-4)

However, the sign of each resistor is used as a resistance value as it is. For example, the resistance value of the resistor R31 is R31. R31 = R32.
Due to the current mirrors of the transistors Q35 and Q36, the collector current of the transistor Q34 becomes 2I.

Further, from the pn junction equations, the equations (1-5) to (1-7) are established for the currents I ₁ , I ₂ , I and the base-emitter voltages Vbe, Vbe2, Vbe3.

Vbe = Vt × ln (I ₁ / Is) (1-5)
_{Vbe2 = Vt × ln (I 2} / (4Is)) ·· (1-6)
Vbe3 = Vt × ln (2I / (2Is)) (1-7)

However, Is is a reverse saturation current and is determined by the transistor. Vt is a thermal voltage and is given by equation (1-8).
Vt = kT / q (1-8)
Here, k is the Boltzmann constant, T is the absolute temperature, and q is the magnitude of the charge of the electrons.
As described above, the emitter areas of the transistors Q32 and Q34 are 4 times and 2 times the emitter area of the transistor Q31, respectively.

From the expressions (1-1) to (1-7), the expressions (1-9) and (1-10) are obtained.

_{I = I 1 = I 2 =} Vt × ln (4) / R33 ·· (1-9)
V ₁ = Vbe + I × R31
= Vbe + (R31 / R33) Vt × ln (4) (1-10)

  From the expressions (1-8) and (1-9), it can be seen that the current 2I flowing through the branches of the connection points Vo3 and Vo1 is proportional to the absolute temperature T. Thus, in the present embodiment, the first reference voltage source 30 includes the first constant current source 40 that causes the constant current 2I having a positive temperature coefficient to flow between the connection points Vo1 and Vo3.

Here, the voltage at the node Vo1, that is, the first to voltages _{V 1} to temperature compensation, when the differential of the first temperature T of voltages _{V 1} to zero, (1-8) - (1-10) below Thus, the expression (1-11) is obtained.

dVbe / dT = − (R31 / R33) k × ln (4) / q (1-11)

However, the temperature coefficient of the resistance values of the resistors R31 to R33 is set to zero.

Therefore, the first voltage V ₁ can be expressed by the expression (1-12) from the expressions (1-10) and (1-11).

V ₁ = Vbe−T × dVbe / dT (1-12)

Thus, (1-11) resistance so as to satisfy the formula R31 (= R32), by choosing R33, the voltage _{V 1} is the temperature as the first-order term of the temperature T becomes zero Can be compensated.

Thus, the band gap reference voltage source generates a voltage proportional to the thermal voltage Vt having a positive temperature coefficient in the resistors R31 and R32 by the transistors Q31 and Q32 and the resistor R33. The base-emitter voltage Vbe of the transistor Q31 and a voltage proportional to the thermal voltage Vt generated in the resistor R31 are added with the amplification action of the transistor Q34 using the current mirror as an active load. As a result, the connection point Vo1 becomes a first voltage _{V 1} which is a temperature compensation (1-12) below.

For example, Vbe = 0.65V, dVbe / dT = -2mV, When T = _300K, a _V 1 = 1.25V.
The transistor Q37, the transistor Q31, Q32, Q34 over to form a loop back to the transistor Q34 along with stabilizing the first voltage _{V 1.}

Next, consider a case where the first diode circuit 10a, the first resistor R20, and the transistor Q13, which are connected in series with each other between the connection points Vo1 and Vo3, are inserted.
The current 2I flowing between the connection points Vo1 and Vo3 is a constant current having a positive temperature coefficient according to the equation (1-9), and the first diode circuit 10a and the first resistor R20 have a variation due to temperature. Voltages with opposite signs are generated. Here, all of the first transistors 11a to 11c constituting the first diode circuit 10a are equivalent to the transistor Q31.

Transistor Q12 (second reference voltage source) and an equivalent to the transistor Q13, a second voltage _{V 2} is outputted to the output terminal Vout from the emitter of the transistor Q12 is connected between the first resistor R20 and the transistor Q13 It is equal to the voltage at the point Vo2.

Second voltage _{V 2} can be expressed by (1-13) from equation (1-9) below.

V ₂ = V ₁ + 3 × Vbe + 2I × R20
= 4 x Vbe
+ ((R31 + 2 × R20) / R33) Vt × ln (4) (1-13)

Here, for temperature compensation of the second voltage _{V 2,} when the derivative with the second temperature T of the voltage _{V 2} to zero, (1-8), (1-13) from equation (1-14) The formula is obtained.

4 × dVbe / dT =
-((R31 + 2 * R20) / R33) k * ln (4) / q .. (1-14)

Second voltage _{V 2} at this time, (1-13) and (1-14) below, can be expressed by (1-15) below.

V ₂ = 4 × (Vbe−T × dVbe / dT) (1-15)

Thus, by choosing the resistance value of the first resistor R20 so as to satisfy the (1-14) wherein the second voltage V _2, the temperature as the first-order term of the temperature T is zero Can be compensated.
Also, at the same time the resistance R31, R33, can be temperature compensated to be (1-11) by selecting so as to satisfy the equation, the differential of the first temperature T of voltages V ₁ also zero.

For example, Vbe = 0.65V, dVbe / dT = -2mV, When T = _300K, a _{V 1 = 1.25V, V 2 =} 5V. As the power supply Vcc = 15 to 30V, the second voltage V ₂ = 5V can be supplied to a circuit such as a CMOS.

In the equations (1-13) to (1-15), the temperature compensation is performed for the second voltage V2. However, when the first voltage V ₁ is temperature compensated, the temperature compensation may be performed for the difference V ₂ −V ₁ between the second voltage V ₂ and the first voltage V ₁ . That is, temperature compensation may be performed for the sum of the voltage across the first diode circuit 10a and the voltage across the first resistor R20.

Therefore, by setting the resistance value of the first resistor R20 so that the derivative of the combined voltage of the voltage across the first diode 10a and the voltage across the first resistor R20 with respect to temperature becomes zero. a second voltage V ₂ can be temperature compensated. The same applies to other embodiments described below.

In the present embodiment, as the first diode circuit 10a, a configuration in which three first transistors 11a to 11c each having a base and a collector are connected in series is illustrated. However, the present invention is not limited to this, and a power supply circuit that supplies a _second voltage V ₂ that is an integral multiple of the _first voltage V ₁ by connecting an arbitrary number of first transistors in series is configured. can do.

  That is, the first diode circuit 10a and the first resistor R20 are inserted in the branch (between the connection points Vo1 and Vo3) in which the constant current I having a positive temperature coefficient of the first reference voltage source 30 flows. Then, if the variation due to the temperature of the voltage generated at both ends of the first diode circuit 10a and the variation due to the temperature of the voltage generated at both ends of the first resistor R20 are set to have the same magnitude and opposite signs. Good.

  Incidentally, in the present embodiment, the first resistor R20 is used. A configuration in which this resistance is included in the resistors R31 and R32 of the first reference voltage source 30, that is, a configuration in which the resistance values of the resistors R31 and R32 are R31 = R32 and R31 + 2 × R20, respectively, can be considered.

However, when the resistance is formed on the semiconductor substrate with high accuracy, it is desirable that the area occupied by the resistance is large and the resistance value is small because the use area can be small.
When the resistance value of the first resistor R20 is included in the resistors R31 and R32, since R31 = R32, a double resistance value is required, and thus an area corresponding to a quadruple resistance value 4 × R20 is required.

Further, when including the resistance of the first resistor R20 to the resistor R31, R32, when the second voltage V ₂ to the temperature compensated first voltage V ₁ is a voltage which is not temperature compensated.
Therefore, in order to obtain a constant current that is temperature compensated, it is necessary to use a high second voltage V _2, the resistance value R11 increases. For example, in this embodiment, the second voltage V ₂ is for four times the first voltage V _1, the resistance value R11 becomes four times, the area required is increased.

Thus, according to the power supply circuit 60a of the present embodiment, in a small occupied area can be supplied with constant voltage (second voltage) V ₂ and the constant current I ₀ that is temperature compensated from the power supply Vcc.
Incidentally, in the power supply circuit 60a of the present embodiment, the second voltage V ₂ has the limitation that a first integer multiple of the voltage V _1.

In order to obtain a temperature-compensated arbitrary voltage, a configuration is known in which the output voltage of a temperature-compensated bandgap reference voltage source is amplified by an amplifier.
FIG. 2 is a circuit diagram of a power supply circuit of a comparative example.
As shown in FIG. 2, the power supply circuit 160 of the comparative example, a power supply circuit to obtain an arbitrary voltage is amplified by the amplifier output voltage V ₁ of the Widlar band-gap reference voltage source 30.

For reference voltage source 30 is the same as the first reference voltage source 30 shown in FIG. 1, the connection point Vo1, and outputs the voltages V ₁ which is temperature compensated.
Transistors Q107 and Q108 constitute a differential amplifier. This differential amplifier uses an active load of lateral PNP transistors Q104 and Q105 as a load to widen the dynamic range. Further, by applying negative feedback through the emitter follower of the transistor Q106 and the resistors R162 and R163, the amplifier has a gain A = (1 + R162 / R163) times.

Therefore, voltage _{V 2} is output to the transistor Q106 becomes a gain A times the voltage _{V 1,} the resistors R162, R163, can be arbitrarily set.
Furthermore, as shown in FIG. 2, by connecting a resistor R161 to the emitter of the transistor Q101, and passing a constant current _{I 0.} This current I ₀ is copied by the current mirror (transistors Q102 and Q103, Q109 and Q110), and is output from the collector of the transistor Q111 to the output terminal Iout.

As described above, the power supply circuit 160 of the comparative example is a series regulator having an arbitrary output voltage V ₂ and a constant current I ₀ with no temperature change.
However, as the power supply circuit 160 of the comparative example, the configuration to output an arbitrary voltage V ₂ by amplifying the voltages V ₁ by the amplifier, it has the following problems.

(A) The occupied area of the resistors R162 and R163 increases.
(A) Noise enters from the power source Vcc at high frequencies.
The reason why the area occupied by the resistors R162 and R163 is increased is that the resistors R162 and R163 are resistors that set the gain of the amplifier, and therefore need to be formed with high accuracy. Further, the resistors R162 and R163 are connected in parallel between the output terminal Vout and the ground GND, and therefore need to have a high resistance value.

The reason (i) that noise enters from the power source Vcc at high frequency is that the open-loop gain of the differential amplifiers of the transistors Q107 and Q108 decreases at high frequency and does not function as a negative feedback amplifier. In particular, there is a problem in the high frequency characteristics of the lateral PNP transistors Q102 and Q103 used as active loads.
At a high frequency at which the open loop gain is reduced, noise enters from the power supply Vcc via the parasitic capacitance C105 of the transistor Q105.

FIG. 3 is a graph showing simulation data of the external power supply noise blocking performance of the power supply circuit shown in FIG.
In Figure 3, the power supply Vcc of the power supply circuit 160 of the comparative example, the DC voltage and AC signal Vn (amplitude 1V, frequency f) as a noise in the case of inputting the voltage _{V 1} and the voltage at the output terminal Vout of the connection point Vo1 it represents the AC signal (noise) component of the calculation result of V _2. The horizontal axis represents the frequency f, and the vertical axis represents the decibel value of the AC signal (noise) component.

As shown in FIG. 3, in the power supply circuit 160 of the comparative example, the transfer characteristic from the power supply Vcc to the output terminal Vout exceeds 0 dB and becomes positive at the peak of 9 MHz.
That is, noise intrudes from the power supply Vcc to the output terminal Vout.
This is particularly problematic when the power supply Vcc is noisy, such as when the power supply Vcc drives a power device.

FIG. 4 is a graph showing the simulation data of the external power supply noise blocking performance of the power supply circuit shown in FIG.
In FIG. 4, when the AC signal Vn (amplitude 1V, frequency f) is input as the DC voltage and noise to the power supply Vcc of the power supply circuit 60a of the present embodiment, the voltage V ₁ (first voltage) at the connection point Vo1. ) And the calculation result of the AC signal (noise) component of the voltage V ₂ (second voltage) of the output terminal Vout. The horizontal axis represents the frequency f, and the vertical axis represents the decibel value of the AC signal (noise) component.

As shown in FIG. 4, in the power supply circuit 60a of the present embodiment, the transfer characteristic from the power supply Vcc to the output terminal Vout has a peak at 600 MHz but does not exceed 0 dB, and is negative at all frequencies.
Thus, in the power supply circuit 60a, the intrusion of noise from the power supply Vcc to the output terminal Vout is smaller than in the comparative example. Further, since a high resistance having a large occupied area is not used, the chip area can be reduced.

Incidentally, in the power supply circuit 60a of the present embodiment, the second voltage V ₂ is the restriction that the first integer multiple of the voltage V _1, it is also possible to configure the power supply to output an arbitrary voltage.
FIG. 5 is a circuit diagram illustrating the configuration of a power supply circuit according to another embodiment of the invention.
As shown in FIG. 5, the power supply circuit 60b of the present embodiment is different from the power supply circuit 60a in that the first diode circuit 10b is used and the transistor Q13 is not provided.

  The first diode circuit 10b is connected to the first transistors 11b to 11c in which the base and the collector are connected in the first diode circuit 10a of the power supply circuit 60a, and the second resistor R12 is connected between the base and the emitter. In this configuration, the third resistor R13 is replaced with the second transistor 12 connected between the base and the collector. Since other than this is the same as that of the power supply circuit 60a, description thereof is omitted.

The current flowing through the first diode circuit 10b and the first resistor R20 is 2I, which is the same as that of the power supply circuit 60a shown in FIG. Current flowing through the second resistor R12 and the third resistor R13 and sufficiently small, the second voltage _{V 2} is given by equation (2-1).

V ₂ = V ₁ + (1 + α) Vbe12 + 2I × R20 (2−1)

However, α = R13 / R12, and Vbe12 is the base-emitter voltage of the second transistor 12.

Here, when the emitter area of the second transistor 12 is equal to the emitter area of the transistor Q31 and Vbe12 = Vbe, (2-9), (1-10), and (2-1) 2) It can be expressed as

V ₂ = V ₁ + (1 + α) Vbe
+ (2 × R20 / R33) Vt × ln (4) (2−2)

To temperature compensation the second voltage V _2, when the derivative with the second temperature T of the voltage V ₂ to zero, is obtained (2-3) below.

dV ₂ / dT = dV ₁ / dT + (1 + α) dVbe / dT
+ (2 × R20 / R33) k × ln (4) / q
= 0 (2-3)

At this time, the second voltage _{V 2} is (1-12), (2-2) and (2-3) equation is expressed as (2-4) below.

V ₂ = (2 + α) (Vbe−T × dVbe / dT) (2-4)

First voltages _{V 1} can be temperature compensated by choosing resistors R31, R33 so as to satisfy (1-11) below. Therefore, by selecting the resistance value of the first resistor R20 and the ratio α = R13 / R12 of the second resistor R12 and the third resistor R13 so as to satisfy the expression (2-3), The voltage V ₂ can be temperature compensated so that the first-order term of the temperature T becomes zero. Further, since a current of 2I flows through the first resistor R20, the resistance value of the first resistor R20 can be made smaller than when combined with the resistor R31 (= R32).

Thus, according to the power supply circuit 60b of the present embodiment, in a small occupied area can be supplied with constant voltage (second voltage) V ₂ and the constant current I ₀ that is temperature compensated from the power supply Vcc.
The second voltage V ₂ may be variable. Further, since no amplifier is used, there is little intrusion of noise from the power supply Vcc.

  In the present embodiment, as the first diode circuit 10b, a first transistor 11a having a base and a collector connected, a second resistor R12 is connected between the base and the emitter, and a third resistor R13 is provided. A configuration in which the second transistor 12 connected between the base and the collector is connected in series is illustrated. However, the present invention is not limited to this, and any number of first transistors can be used.

FIG. 6 is a circuit diagram illustrating the configuration of a power supply circuit according to another embodiment of the invention.
As shown in FIG. 6, in the power supply circuit 60c of the present embodiment, the first diode circuit 10c and the first resistor R20 are connected to the input terminal Vo0 whose absolute value of the first reference voltage source 30 is low. And the ground GND is different from the power supply circuit 60a.

  The first diode circuit 10c includes first transistors 14a to 14c in which a base and a collector are connected. Here, the emitter area of each of the first transistors 14a to 14c is set to four times the emitter area of the transistor Q31.

Assuming that the absolute value of the first reference voltage source 30 is V _{0 at} the connection point Vo0 between the low voltage side and the first diode circuit 10c, the voltage difference V _{1 with} respect to the voltage V _{1 at the} connection point Vo1. -V ₀ is given by equation (3-1) from equation (1-10).

V ₁ −V ₀ = Vbe
+ (R31 / R33) × Vt × ln (4) (3-1)

Conditions for temperature compensation of the voltage difference _V 1 -V ₀ is the same as (1-11) below. At this time, the expression (3-1) is expressed as the expression (3-2).

V ₁ −V ₀ = Vbe−T × dVbe / dT (3-2)

The constant current I ₀ flowing through the reference current source Q11, the current I flowing through the transistors Q31 and Q32 of the first reference voltage source 30 and the sum 4I + I ₀ of the current 2I flowing through the transistor Q34 are the first diode circuit 10c, Flows through resistor R20.

Here, assuming that I ₀ << I and the base-emitter voltage of each of the first transistors 14a to 14c is equal to the base-emitter voltage Vbe of the transistor Q31, the second voltage V ₂ is (3 -3) is given by the equation.

V ₂ = (V ₁ −V ₀ ) + 3 × Vbe + (4I + I ₀ ) R20
_{= (V 1 -V 0) (} 1 + R20 / R11)
+ 3 × Vbe + 4I × R20 (3-3)

To temperature compensation the second voltage V _2, when the derivative with the second temperature T of the voltage V ₂ to zero, is obtained (3-4) below.

_{dV 2 / dT = d (V} 1 -V 0) / dT × (1 + R20 / R11)
+3 x dVbe / dT
+ (4 × R20 / R33) k × ln (4) / q
= 0 (3-4)

When temperature compensation is performed so as to satisfy the expression (1-11), d (V ₁ −V ₀ ) / dT = 0, and the constant current I ₀ is temperature compensated. At this time, the second voltage _{V 2} is (3-2) than to (3-4) below is expressed as (3-5) below.

V ₂ = 4 (Vbe−T × dVbe / dT) + I ₀ × R20
= (4 + R20 / R11) × (Vbe−T × dVbe / dT) (3-5)

The voltage difference V ₁ −V ₀ can be temperature compensated by selecting the resistors R31 and R33 so as to satisfy the expression (1-11). Therefore, so as to satisfy the (3-4) equation, by setting the resistance value of the first resistor R20, the second voltage V _2, the temperature as the first-order term of the temperature T becomes zero Can be compensated. Further, the resistance value of the first resistor R20 can be reduced.

Thus, according to the power supply circuit 60c of the present embodiment, in a small occupied area can be supplied with constant voltage (second voltage) V ₂ and the constant current I ₀ that is temperature compensated from the power supply Vcc.
The second voltage V ₂ is also, by adjusting the resistance R11, can be made variable. Further, since no amplifier is used, there is little intrusion of noise from the power supply Vcc.

  In the present embodiment, a case where three first transistors 14a to 14c are used as the first diode circuit 10c is illustrated. However, the present invention is not limited to this, and a configuration having an arbitrary number of first transistors can be employed. Further, similarly to the power supply circuit 60 b illustrated in FIG. 5, the second transistor 12 may be included. However, the emitter area of the second transistor 12 is set to four times the emitter area of the transistor Q31.

In the power supply circuit 60c shown in FIG. 6, it is assumed that the relationship of I ₀ << I is established between the constant current I ₀ and the current I flowing through the transistor Q31 of the first reference voltage source 30. That is, it is assumed that the base-emitter voltage of each of the first transistors 14a to 14c is equal to the base-emitter voltage Vbe of the transistor Q31.

When the constant current I ₀ is approximately equal to or larger than the current I flowing through the transistor Q13, the current 4I + I ₀ flowing through each of the first transistors 14a to 14c is equal to the current I flowing through the transistor Q31. It can not be said. For this reason, a deviation occurs between the base-emitter voltage of each of the first transistors 14a to 14c and the base-emitter voltage Vbe of the transistor Q31.

However, in this case, another power supply circuit can be used.
FIG. 7 is a circuit diagram illustrating the configuration of a power supply circuit according to another embodiment of the invention.
In Figure 7, the constant current I ₀ is shows a configuration example of a power supply circuit 60d which can be used in the case of a size comparable to the current I flowing through the transistor Q13.

As shown in FIG. 7, in the power supply circuit 60d of the present embodiment, a current I is passed through a connection point between the first diode circuit 10d and the first resistor R20 by a current mirror including transistors Q14 and Q15. Yes. The constant current _{I 0} is output to the output terminal Iout from the collector of the transistor Q16. Other points are the same as those of the power supply circuit 60c.

  Here, the first diode circuit 10d includes first transistors 15a to 15c in which a base and a collector are connected. Here, the emitter area of each of the first transistors 15a to 15c is set to 5 times the emitter area of the transistor Q31.

Further, the transistors Q14, Q15, Q16, and the resistors R14, R15, R16 are set so that currents I ₁ , I _{0 obtained} by copying the constant current I ₀ flowing through the transistor Q14 to the transistors Q15, Q16 flow, respectively.
Equations (4-1) to (4-2) are established for the resistors R14, R15, and R16.

I ₁ = I ₀ × R14 / R15 (4-1)
R14 = R15 (4-2)

However, it is assumed that the base-emitter voltages of the transistors Q14 and Q15 are sufficiently smaller than the voltages at both ends of the resistors R14 and R15. Further, I ₁ ≈I ₀ ≈I.

Assuming that the voltage at the connection point Vo0 between the first reference voltage source 30 and the first diode circuit 10d is V ₀ , the voltage difference V ₁ −V _{0 with} respect to the voltage V _{1 at the} connection point Vo1 is ( 3-1) is given by the equation.
Further, conditions for temperature compensating the voltage difference _V 1 -V ₀ is the same as (1-11) below. At this time, the expression (3-1) is expressed as the expression (3-2).

Reference current source Q11 constant current _{I 0} flowing through the current flowing through the transistor Q31 of the first reference voltage source 30, Q32, respectively I, the sum 4I + _{I 0} of the current 2I through the transistor Q34, flows through the first diode circuit 10d.
Also, the sum 4I + I ₀ + I _{1 of the} current 4I + I ₀ flowing through the first diode circuit 10d and the current I ₁ from the transistor Q15 flows through the first resistor R20.

Here, from I ₀ ≈I, if the base-emitter voltage of each of the first transistors 15a to 15c is equal to the base-emitter voltage Vbe of the transistor Q31, the second voltage V ₂ is (4 From (-1) Formula, it represents like (4-3) Formula.

V ₂ = (V ₁ −V ₀ ) + 3 × Vbe + (4I + I ₀ + I ₁ ) R20
= (V ₁ −V ₀ ) × (1+ (1 + R14 / R15) × R20 / R11)
+ 3 × Vbe + 4I × R20 (4-3)

To temperature compensation the second voltage V _2, when the derivative with the second temperature T of the voltage V ₂ to zero, is obtained (4-4) below.

_{dV 2 / dT = d (V} 1 -V 0) / dT
× (1+ (1 + R14 / R15) × R20 / R11)
+3 x dVbe / dT
+ (4 × R20 / R33) k × ln (4) / q
= 0 (4-4)

(1-11) When the temperature compensated so as to satisfy the _{equation, d (V 1 -V 0)} / dT = 0 , and the constant current _{I 0} is temperature compensated. At this time, the second voltage _{V 2} is (4-3) from - (4-4) equation is expressed as (4-5) below.

_{V 2 = 4 (Vbe-T} × dVbe / dT)
+ (1 + R14 / R15) × I ₀ × R20
= (4+ (1 + R14 / R15) × R20 / R11)
× (Vbe−T × dVbe / dT) (4-5)

The voltage difference _V 1 -V ₀ can be temperature compensated by choosing resistors R31, R33 so as to satisfy (1-11) below. Therefore, so as to satisfy the (4-4) equation, by setting the resistance value of the first resistor R20, the second voltage V _2, the temperature as the first-order term of the temperature T becomes zero Can be compensated. Further, the resistance value of the first resistor R20 can be reduced.

Thus, according to the power supply circuit 60d of this embodiment, a small occupied area can be supplied with constant voltage (second voltage) V ₂ and the constant current I ₀ that is temperature compensated from the power supply Vcc.
The second voltage _{V 2,} by adjusting the ratio of the resistance values R14 / R15, it can be made variable. Further, since no amplifier is used, there is little intrusion of noise from the power supply Vcc.

As described above, the magnitude of the constant current I _0, I 0 the power supply circuit 60c when the _«I, also by using the power circuit 60d when the I ₀ ≒ I, without the design becomes difficult It is possible to supply a highly accurate power supply circuit with a temperature-compensated constant voltage V ₂ and a constant current I ₀ .

  In addition, in the power supply circuit 60d of a present Example, the case where it has three 1st transistors 15a-15c as the 1st diode circuit 10d is illustrated. However, the present invention is not limited to this, and a configuration having an arbitrary number of first transistors can be employed. Further, similarly to the power supply circuit 60 b illustrated in FIG. 5, the second transistor 12 may be included. However, the emitter area of the second transistor 12 is set to 5 times the emitter area of the transistor Q31.

  In the power supply circuits 60a to 60d of the present embodiment described above, the configuration of the power supply circuit that supplies the positive power supply Vcc from the outside and outputs the positive first and second voltages is exemplified. However, the present invention is not limited to this, and a power supply circuit that supplies a negative power supply and outputs negative first and second voltages can be configured by a similar configuration.

The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. For example, regarding the specific configuration of each element constituting the power supply circuit, as long as a person skilled in the art can implement the present invention by selecting appropriately from a known range and obtain the same effect, the present invention Included in the range.
Moreover, what combined any two or more elements of each specific example in the technically possible range is also included in the scope of the present invention as long as the gist of the present invention is included.

  In addition, all power supply circuits that can be implemented by a person skilled in the art based on the above-described power supply circuit as an embodiment of the present invention belong to the scope of the present invention as long as they include the gist of the present invention. In addition, in the category of the idea of the present invention, those skilled in the art can conceive of various changes and modifications, and it is understood that these changes and modifications also belong to the scope of the present invention. .

10a to 10d First diode circuit 11a to 11c, 14a to 14c, 15a to 15c First transistor 12 Second transistor 30 First reference voltage source 40 First constant current source 60a to 60d Power supply circuit 160 Power supply circuit C105 Parasitic capacitance GND Ground Q11 Reference current source Q12 Second reference voltage source Q14 to Q16, Q31 to Q37 Transistor Q101, Q106 to Q111 Transistor Q102 to Q105 PNP transistor R12 Second resistor R13 Third resistor R11, R14 to R15 , R31 to R33, R161, 162 Resistor R20 First resistor Vcc Power supply Vo0, Vo1, Vo2, Vo3 Connection point Iout, Vout Output terminal

Claims (5)

A first reference voltage source having a first constant current source that outputs a voltage having a positive temperature coefficient by inputting a voltage to both ends from the outside, and that outputs a first voltage having a zero temperature coefficient;
A first diode circuit having one end connected to the first constant current source;
One end is connected to the other end of the first diode circuit, and the variation due to the temperature of the voltage generated at both ends is equal in magnitude to the variation due to the temperature of the voltage generated at both ends of the first diode circuit, and the sign is opposite. A first resistor whose resistance value is set to be
A second reference voltage source connected to the other end of the first resistor and outputting a second voltage;
A reference current source for inputting the first voltage and outputting a constant current having a temperature coefficient of zero;
A power supply circuit comprising: A first reference voltage source that inputs a voltage from outside to both ends and outputs a first voltage having a temperature coefficient of zero;
A first diode circuit having one end connected to the input terminal on the low voltage side of the absolute value of the first reference voltage source;
The variation due to the temperature of the voltage connected between the other end of the first diode circuit and the ground is equal in magnitude to the variation due to the temperature of the voltage occurring at both ends of the first diode circuit. A first resistor whose resistance value is set so that the sign is reversed;
A reference current source for inputting the first voltage and outputting a constant current;
A power supply circuit comprising:   The resistance value of the first resistor is set such that the differential of the combined voltage of the voltage at both ends of the first diode circuit and the voltage at both ends of the first resistor is zero. The power supply circuit according to claim 1 or 2.   The power supply circuit according to claim 1, wherein the first diode circuit includes a first transistor having a base and a collector connected to each other. The first diode circuit includes:
A first resistor;
A second resistor;
A second transistor in which the first resistor is connected between a base and an emitter, and the second resistor is connected between a base and a collector;
5. The power supply circuit according to claim 1, comprising:

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