JP3173015B2 - Electronic circuit in IC - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic circuit in an IC, and more particularly, to a novel electronic circuit in an IC which has no temperature dependence of output.

[0002]

2. Description of the Related Art Many electronic circuits in an LSI require a resistor. Such electronic circuits are shown in FIGS.
There are the following. The electronic circuit shown in FIG. 3 is a current source circuit using the Zener diode ZD as a reference.
Q1 and Q2 are first and second transistors whose emitters and bases are commonly connected to form a current mirror, and ZD is reference voltage generating means connected between the collector of the first transistor Q1 and ground. A reference zener diode, Q3, is a third transistor having a collector connected to the collector of the transistor Q2, which is a reference voltage detecting transistor. The base is connected to a connection point between the Zener diode ZD and the collector of the transistor Q1. . R is a current regulating resistor, which is connected in series with the emitter of the transistor Q3. Q
Reference numeral 4 denotes a fourth transistor connected in series with the current regulating resistor R, and is current mirror-connected to an output transistor Q5 as a fifth transistor. In this constant current source circuit, a voltage obtained by subtracting the sum 2V _BE of the base-emitter voltage when the transistors Q3 and Q4 are turned on from the terminal voltage Vz of the Zener diode ZD is added to the current regulating resistor R, and accordingly, (Vz−2V _BE ) / R current I
Flows to Then, the same current as that of the transistor Q
4 flows into the transistor Q5 having a current mirror relationship. The current flowing through the transistor Q5 is the output current I
_out .

The electronic circuit shown in FIG. 4 is a BiCMOS IC
Is a constant current circuit configured so that the base-emitter voltage V _BE of the transistor is used as a reference voltage.
OSFETs M1, M2, M5 and N-channel MOSF
ETM3 and M4 are used. And P channel M
A first circuit is constituted by a series circuit of the OSFET M1, the N-channel MOSFET M3, and the reference transistor Qr, and a second circuit having a current mirror relationship with the series circuit is a P-channel MOSFET M2 and an N-channel M
It is composed of an OSFET and a current regulating resistor R. Then, the same voltage as the base-emitter voltage V _{BE of} the reference transistor Qr is applied to the resistor R. Therefore, V
_A current I determined by _BE / R = I flows through the resistor R, and a current Iout substantially equal to the current _Iout is supplied to the third circuit M
Output through OSFET M5.

The current regulating resistor R is composed of a diffusion resistor formed of a diffusion layer selectively formed on the surface of the semiconductor substrate or a semiconductor layer of, for example, polysilicon formed on the semiconductor substrate via an insulating layer. It consisted of a semiconductor layer resistor.

[0005]

The current regulating resistor R has a temperature coefficient of resistance regardless of whether it is constituted by a diffusion resistor or a semiconductor layer resistor. The current has temperature dependence. This is because the semiconductor layer resistance has a positive temperature coefficient of resistance and the diffusion resistance has a negative temperature coefficient of resistance.
There is no problem if the resistance temperature coefficient of the resistor is a value convenient for the electronic circuit, but such a case is extremely rare. Specifically, in the case of the circuit of FIG. 3, a current regulating resistor having a temperature coefficient of resistance that cancels the temperature dependency of the Zener diode ZD is required.
Since the circuit of the base-emitter voltage V _BE of the transistor Qr is temperature dependent, it is necessary to so as to cancel it, like having a resistance temperature coefficient can be canceled Creating resistance has traditionally been difficult.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem. In an electronic circuit in an IC, a resistor having an arbitrary temperature coefficient of resistance is formed, and using the resistor, there is no temperature dependency. The purpose is to obtain output characteristics.

[0007]

An electronic circuit in an IC according to the first aspect of the present invention includes a third transistor connected in series to the second transistor among the first and second transistors forming a current mirror. A base of a third transistor is connected to the first transistor, first and second resistors are connected to the third transistor, and a current mirror circuit is connected to the second resistor; One of the second resistors is constituted by a diffused resistor and the other is constituted by a semiconductor layer resistor, and the first and second resistors are combined so as to have a predetermined temperature coefficient. An electronic circuit in the IC according to claim 2, wherein the first circuit having the reference transistor, the second circuit having the current regulating resistor, and the third circuit supplying the output current constitute a current mirror with each other. A connected circuit, wherein an additional resistor connected in series with the reference transistor is provided in the first circuit, and a temperature dependency of an output current is obtained by using a resistor having a different temperature coefficient between the additional resistor and the current defining resistor. Is set to 0.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an electronic circuit in an IC of the present invention will be described in detail with reference to the illustrated embodiments. FIG. 1 is a circuit diagram showing one embodiment of an electronic circuit in an IC of the present invention. This embodiment is different from the conventional circuit shown in the figure in that a semiconductor layer resistor, specifically, a polysilicon resistor Rp made of polysilicon and a diffusion resistor Rd are connected in series as a current regulating resistor. Although they differ in the point, they are common in points other than the current regulating resistor, and the common points have already been described, so that the description will be omitted, and only the current regulating resistor will be described.

Assuming that the resistance value of the polysilicon resistor Rp is Rp, Rp is expressed by the following equation (1). Rp = Rp ₀ [1 + α _p (T−T _o )] Equation 1 where α _{p is the} temperature coefficient of resistance of the polysilicon resistor Rp, R
p _o : polysilicon resistance when temperature T is T ₀ . Also,
Assuming that the resistance value of the diffusion resistor Rd is Rd, Rd is represented by the following equation 2. _{Rd = Rd o [1 + α} d (T-T 0)] ··· Equation 2 where, alpha _d: resistance temperature coefficient of the diffused resistor Rd, Rd _o: polysilicon resistor when the temperature T is _{T 0.} Note that α _p <0,
α _d > 0.

By the way, the series resistance of the diffusion resistance Rd and the polysilicon resistance Rp, which is the current regulating resistance, is determined by the Zener voltage Vz from the transistor Q3 and the transistor Q3.
4, a current having a value obtained by subtracting the sum of the base-emitter voltages V _BE at the time of ON, that is, 2 V _BE is applied (note that
Thereafter, _VBE is the base voltage when the transistor is on.
It means the voltage between the emitters. ). Therefore, if the output current of the circuit is I _out , the following equation 3 holds. This is because the current flowing in the second circuit is equal to the output current I _out flowing in the third circuit.

Vz = I _out (Rp + Rd) + 2V _BE Equation 3 Next, the following Equation 4 is obtained by partially differentiating Equation 3 with temperature T. ∂ Vz / ∂ T = (Rp + Rd) ∂ I out / ∂ T + I out [(∂ Rp / ∂ T) + (∂ Rd / ∂ T) +2 ∂ V BE / ∂ T ··· Equation 4 above formula (4) When both sides are divided by (Rp + Rd) I _out , the following equation (5) is obtained. Here, Rp + Rd is defined as R. _{∂ Vz / ∂ T · 1 /} (RI out) = ∂ I out / ∂ T · 1 / I out + ∂ R p / ∂ T · 1 / R + ∂ Rd / ∂ T · 1 / R + 2 ∂ V BE / ∂ T _{· 1 / (RI ou t)} ··· formula 5

One of the important characteristics required for the current source circuit is that the temperature dependence of the output current I _out is small,
If possible, make it 0. Therefore, the above equation 5 Odor <br/> Te _{∂ Vz / ∂ T · RI out} = 0. Then, the following equation 6 is established. [(∂ Vz / ∂ T) -2 (∂ V BE / ∂ T) -I out · (∂ Rp / ∂ T) - I out · (∂ Rd / ∂ T)] / R · I out = 0 ·· Equation 6 If the circuit conditions are set so that Equation 6 holds, the temperature dependence of the output current I _out can be made zero.

Therefore, numerical values are given to the constants and temperature characteristics of the above equation 6 to which specific numerical values can be given as follows. ∂ Vz / ∂ T ≒ 2.5mV / ℃, Vz
_{≒ 6.2V, ∂ V BE / ∂} T ≒ -2mV / ℃, V BE ≒
0.6 V, α _d ≒ 2000 ppm / ° C., α _p ≒ -100
0 ppm / ° C. Then, the output current I _{out is set} to 10
It is set to 0 μA. Then, ∂ Rp / ∂ T = R
Since p _o α _p and ∂Rd / ∂T = Rd _o α _d , by substituting these into equation 6, the following equation 7 is obtained. 0 = (∂ Vz / ∂ T ) -2 (∂ V BE / ∂ T) - [ in _{I out (Rp o α p +} R d o α d) ··· Equation 7 Equation 7 by substituting numerical values described above By rearranging, the following equations 8 and 9 are obtained. _{4.5mV / ℃ = 100μA (Rp o} α p + Rd o α d) ··· Equation _{8 45 = Rp o α p +} Rd o α d ··· Equation 9

Next, by substituting specific numerical values into Equation 3, the following Equation 10 is obtained. _{6.2V = 100μAR o + 2 × 0.6V} ··· formula _{10 ∴R o (≡Rp o + Rd} o) = 50KΩ

[0015] In this _case, and Rp _o = xRd o. That x is a ratio Rd _o of Rp _o. Then, (1
+ _X) Rd o = 50KΩ, and the equation 11 below is obtained when obtaining the Rd _o. Rd _o = R _o / (1 + x) = 50 KΩ / (1 + x) Expression 11 Then, the following calculation can be performed from Expression 9 and Expression 11. _{45 = 50K (xα p + α} d) / (1 + x) = 50 (2-x) / (1 + x) ∴0.9 (1 + x) = 2-x ∴x = 1.1 / 1.9 = 0.58

Therefore, R _o = 50 KΩ and Rd = 31.6.
K.OMEGA., If Rp = 18.4KΩ, it is possible to temperature dependency obtain constant current _{I out} of 100μA 0. Specifically, the temperature characteristics of the Zener diode ZD can be canceled by the resistor R (≡Rp + Rd). Thus, the diffusion resistance Rd and the semiconductor layer resistance R
p is appropriately combined to form a resistor R having an arbitrary temperature coefficient of resistance, whereby the temperature characteristic of the electronic circuit (the constant current source circuit in the present embodiment) is changed to an arbitrary value (in this example, the output current). Can be set to 0).

Here, how the resistance R having an arbitrary temperature coefficient of resistance is obtained by the diffusion resistance Rd and the semiconductor layer resistance Rp will be considered. _{Rd = Rd o [1 + α} d (T-T 0)] Rp = Rp o [1 + α p (T-T 0)] series resistance R of the resistance diffused resistor Rd and the semiconductor layer resistance Rp
Is represented by the following equation. R = Pp + Rd Then, when the temperature dependence of the series resistance R is obtained, that is, when the partial differential is performed with respect to the temperature T, the following equation 12 is obtained.

[0018] The ∂ R / ∂ T = ∂ Rp / ∂ T + ∂ Rd / ∂ T ··· formula 12 alpha _r a resistance temperature coefficient of resistance R, the following equation 13 is obtained from the above equation 12. _{α r ≡ ∂ R / ∂ T} · 1 / R = [(∂ Rp / ∂ T) + (∂ Rd / ∂ T)] / R = (Rp o α p + Rd o α d) ··· formula 13 where , when _{Rp o = xRd o, R o} = Rp o + R
the d = (1 + x) Rd o. Thus _{α r = Rd o (xα p} + α d) / R = α p x / (1+
x) + α _d / (1 + x). Then, when x = 0, α _r = α _d > 0, and
the α _r ≒ <0 when x »0.

Therefore, by changing the ratio of the diffusion resistance Rd and the semiconductor layer resistance Rp, that is, x, the resistance temperature coefficient of the resistance R is intermediate between that of the diffusion resistance Rd α _d and that of the semiconductor layer resistance Rp α _p. It can be any value. The circuit shown in FIG. 1 applies this to the current regulating resistor R of the Zener reference type constant current circuit.

FIG. 2 shows another embodiment of the electronic circuit in the IC of the present invention. In the present embodiment, the diffusion resistance Rd and the semiconductor layer resistance Rp are not connected in series to form one resistance, but two resistances used in different places are one of the diffusion resistance Rd and the other resistance of the semiconductor layer resistance Rp. It is constituted by. That is, in the conventional constant current source circuit shown in FIG. 4 which uses the base-emitter voltage V _BE as a reference voltage, the reference voltage V _BE has a negative temperature coefficient. If the current regulating resistor is constituted by a diffusion resistor having a positive temperature coefficient, it is impossible to cancel the dependence. Even if a polysilicon resistor is used, the absolute value of the temperature coefficient of resistance of the polysilicon resistor is not large enough to be canceled,
The temperature dependence of the output current was only slightly reduced.

In this embodiment shown in FIG. 2, a diffusion resistor Rd is added between a reference transistor Qr and a MOSFET M1 of a constant current source circuit of the type shown in FIG. 4, and a polysilicon resistor Rp is used as a current regulating resistor. This is different from the circuit shown in FIG. 4 in that point, but is common in other points, and the common points have already been described, so that the description is omitted, and the added diffusion resistance Rd
Only the polysilicon resistor Rp which is a current regulating resistor will be described.

In FIG. 2, Rd is a diffusion resistance inserted between the emitter of the reference transistor Qr and the source of the MOSFET M3, and the reference voltage is increased by the resistance Rd. Rp is a current regulating resistor made of a polysilicon resistor. here,
The reference voltage Vref is represented by the following Expression 14. _{Vref = I out Rd + V BE} = I out Rp ··· formula 14 _{V B E:} the base-emitter voltage of the reference transistor Q1

When the above equation (14) is partially differentiated with respect to the temperature T, the following equation (15) is obtained. _{Rd · ∂ I out / ∂ T} + ∂ V BE / ∂ T + I out ∂ Rd / ∂ T = Rp · d I out / ∂ T + I out · ∂ Rp / ∂ T ··· below and to organize the formula 15 Equation 15 Equation 16 become. (Rp-Rd) · ∂ I out / ∂ T + I out · ∂ (Rp-Rd) / ∂ T = ∂ V BE / ∂ T ··· formula 16 Then, the temperature dependency of the output current _{I out} that the 0 Under the condition, ∂I _out / ∂T = 0, the following equation 17 is obtained. I _out · d (Rp−Rd) / dT = dV _BE / dT (17) Here, the output current I _out = 100 μA, V _BE = 0.
_{7V, ∂ V BE / ∂ T} = -2mV / ℃, ∂ Rp / ∂ T =
-500ppm / ℃, ∂ Rd / ∂ T = 3000ppm /
° C, Rd = 3.25 KΩ, Rp = 20.5 KΩ
Becomes

As described above, the reference transistor Q
In order to eliminate the temperature dependency of the output current I _out , a diffusion resistance Rd is added between the emitter of the MOSFET 1 and the source of the MOSFET, and a polysilicon resistance Rp is used as a current regulating resistance to appropriately set the value. Can be

[0025]

According to the first aspect of the present invention, there is provided an electronic circuit in an IC wherein first and second transistors forming a current mirror whose bases are connected in common, and the first and second transistors are connected in series to the second transistor. A third transistor having a base connected to the transistor, first and second resistors connected to the third transistor, and a current mirror circuit connected to the second resistor; And the second resistor
One consists of a diffusion resistor formed on the semiconductor substrate, and the other consists of a semiconductor layer resistor formed on the semiconductor substrate via an insulating film, and the first resistance and the second resistance are defined by a predetermined temperature coefficient. Characterized by having a combination of Therefore, according to the electronic circuit in the IC of claim 1,
Since the first resistor is constituted by a diffusion resistor having a negative temperature coefficient of resistance and the second resistor is constituted by a semiconductor layer resistor having a positive temperature coefficient of resistance, the resistance of the combined resistor composed of the first and second resistors is used. The temperature coefficient can be changed by a combination of the first resistance and the second resistance. Accordingly, even if the output current of the current mirror circuit has a temperature dependency, the temperature dependency of the combined current is determined by the combination of the first resistor and the second resistor. Cancellation can be performed, and the temperature dependency of the output current can be eliminated.

The electronic circuit in the IC according to claim 2 is a base circuit.
A first circuit having at least a reference transistor having an emitter-to-emitter voltage as a reference voltage; a second circuit forming a current mirror with the circuit and having a current regulating resistor receiving the same voltage as the reference voltage; A third circuit for forming a circuit and a current mirror and outputting a current determined by the reference voltage and the current regulating resistor, wherein the three circuits are current mirror-connected to each other, and the first circuit is A resistor is added in series with the reference transistor so as to increase the reference voltage, and the added resistor and the current regulating resistor are temperature dependent on the output current of the third circuit by resistors having different resistance temperature coefficients. It is characterized in that it is configured so as to lose its characteristics. Therefore,
According to the electronic circuit in the IC according to the second aspect, the negative temperature characteristic of the base-emitter voltage V _BE of the reference transistor serving as the reference voltage (about −2 mV / ° C.)
Can be canceled by both the resistor having the same negative temperature characteristic connected in series with the reference transistor and the current regulating resistor having the positive temperature characteristic, and the temperature dependence of the output current can be reduced to 0. Can be

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing one embodiment of an electronic circuit in an IC of the present invention.

FIG. 2 is a circuit diagram showing another embodiment of the electronic circuit in the IC of the present invention.

FIG. 3 is a circuit diagram showing one conventional example.

FIG. 4 is a circuit diagram showing another conventional example.

[Explanation of symbols]

Rd Diffusion resistor Rp Semiconductor layer resistor R Composite resistor ZD Reference Zener diode I _OUT output current M1, M3, Rd, Qr First circuit M2, M4, Rp Second circuit Q5 Third circuit Qr Reference transistor

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 27/04 H01L 21/822

Claims (2)

(57) [Claims] 1. A current mirror whose base is commonly connected.
A first transistor and a second transistor, which are connected in series with the second transistor, and
Transistor with Base Connected to Transistor
And first and second resistors connected to the third transistor.
And anti, the current mirror circuit connected to a second resistor, having a said first and second resistors, one of formed on a semiconductor substrate
Composed of a diffused resistor, the other of which is insulated on the semiconductor substrate
The first resistor and the second resistor have a predetermined temperature coefficient, and are formed of a semiconductor layer resistor formed through a film.
Electronic circuit in an IC characterized by being combined as follows 2. A first circuit having at least a reference transistor using a base-emitter voltage as a reference voltage, a second circuit forming a current mirror with the circuit and having a current regulating resistor receiving the reference voltage, The second circuit and a third circuit for forming a current mirror and outputting the reference voltage and a current determined by the current regulating resistor are connected to each other to form a current mirror. A resistor is added in series with the reference transistor so as to increase the reference voltage, and the added resistor and the current regulating resistor are connected to each other by resistors having different temperature coefficients from each other. Electronic circuit in an IC characterized in that the circuit is eliminated