JP3335848B2 - Comparator circuit and infrared remote control device having the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a comparator circuit having improved temperature characteristics of an offset voltage, and an infrared remote control device provided with the comparator circuit.

[0002]

2. Description of the Related Art A conventional comparator circuit will be described below with reference to FIG. As shown in FIG. 5, a conventional comparator circuit includes a transistor Q constituting a differential amplifier.
31 and Q32, and a comparison input signal is input to each base terminal. The collector terminals of the transistors Q31 and Q32 are connected to the collector terminals of the transistors Q33 and Q34, respectively. Transistors Q33, Q34
In any case, the emitter terminal is connected to the _Vcc line (the positive potential of the power supply).

The transistor Q33 has a base terminal and a collector terminal connected to each other, and is further connected to a base terminal of the transistor Q35. The transistor Q33 and the transistor Q35 form a current mirror circuit. The transistor Q34 has a base terminal and a collector terminal connected to each other, and is further connected to a base terminal of the transistor Q36. The transistor Q34 and the transistor Q36 form a current mirror circuit.

[0004] The collector terminal of the transistor Q35 is connected to the collector terminal of the transistor Q37. The emitter terminal of the transistor Q37 is connected to a ground line (ground potential of a power supply). The transistor Q37 has a base terminal connected to the collector terminal,
Further, the transistor Q38 is connected to the base terminal of the transistor Q38, and the transistor Q37 and the transistor Q38 form a current mirror circuit.

[0005] The collector terminal of the transistor Q36 is connected to the collector terminal of the transistor Q38. The emitter terminal of the transistor Q38 is connected to the ground line. The comparison output signal V _out is output from the collector terminal of the transistor Q38. The emitter terminals of the transistors Q35 and Q36 are respectively connected to the V _CC line.

The emitter terminals of the transistors Q31 and Q32 are connected to each other.
39 are connected to the collector terminal. Transistor Q
An emitter terminal 39 is connected to a ground line. The base terminal of the transistor Q39 is connected to the base terminal of the transistor Q41.

The base terminal of the transistor Q41 is connected to the collector terminal, and this collector terminal is connected to the resistor R4.
2 is connected to the emitter terminal of the transistor Q40. The transistor Q40 has a base terminal and a collector terminal connected to each other, and this connection point is connected to the V _CC line. The transistor Q40 functions as a diode. Transistor Q39 and transistor Q41
Constitutes a current mirror circuit.

[0008] In the above structure, while the comparison input signal V _IN32 to the base terminal of the transistor Q31 is inputted, it compares the input signal V _IN31 to the base terminal of the transistor Q32 is inputted. When _Vin31 = _Vin32 , the comparison output signal V
_out is a binary low level. On the contrary,
The comparison input signals _Vin31 and _Vin32 change, and the transistor Q
31, the current I _31, I ₃₂ flowing through Q32 is, I ₃₂ / I ₃₁ ≧
When 4 is satisfied, the comparison output signal V _out changes to a binary high level.

Here, the base-emitter voltages of the transistors Q31 and Q32 are V _BE31 and V _BE32 , respectively.
Let Boltzmann's constant be k, absolute temperature be T, and charge be q
Then, the following equation is established.

I ₃₁ : I ₃₂ = 1: 4 (1) Vin ₃₁ −V _BE32 = V _in32 −V _BE31 (2) V _BE31 = (kT / q) ln (I ₃₁ / I ₀ ) (3) V _BE32 = (kT / q) ln (I ₃₂ / I ₀ ) (4) From the above equation, the offset voltage ΔV of the comparator circuit is:
The following equation (5) is obtained.

ΔV = V _in31 −V _in32 = V _BE32 −V _BE31 = (kT / q) ln (I ₃₂ / I ₃₁ ) = (kT / q) ln4 (5) It is clear from the above equation (5). The offset voltage Δ
V is an offset component having a positive temperature characteristic ((kT /
q) consists only of ln4). That is, the offset voltage ΔV of the conventional comparator circuit changes in direct proportion to the ambient temperature, as shown by the broken line in FIG. That is, the offset voltage ΔV increases as the ambient temperature increases, and decreases as the ambient temperature decreases.

[0012]

However, in the above-mentioned conventional comparator circuit, the offset voltage ΔV changes in accordance with the fluctuation of the ambient temperature because the offset voltage consists only of the offset component having a positive temperature characteristic. For example, the offset voltage ΔV decreases as the ambient temperature decreases. For this reason, when the ambient temperature is lowered, the offset voltage ΔV is reduced accordingly, and the margin for noise in comparison is reduced, so that the comparator circuit malfunctions due to the noise.

Further, when the above-mentioned conventional comparator circuit is used in an infrared remote control device, it malfunctions as described above, so that there is a problem that a highly reliable device cannot be provided.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has as its object to improve a temperature characteristic of an offset voltage, and to always operate stably even when an ambient temperature fluctuates. And an infrared remote control device provided with the comparator circuit.

[0015]

According to a first aspect of the present invention, there is provided a comparator circuit comprising a differential amplifier, wherein first and second input terminals are supplied with a comparison input signal to each base terminal. Two transistors, first and second constant current circuits connected to the collector terminals of the first and second transistors, respectively, and connected to the first and second constant current circuits to output a comparison output signal. A comparator circuit having a third constant current circuit, wherein the offset voltage is predetermined based on the first to third constant current circuits, has the following invention specific items.

That is, the comparator circuit comprises: (1) first and second resistors having one ends connected to the emitter terminals of the first and second transistors, respectively, and the other ends connected to each other; A fourth constant current circuit connected to the connection point of the first and second resistors and including a third resistor for supplying a bias current of the differential amplifier limited by the third resistor; The first resistor and the second resistor
Have the same temperature coefficient and the temperature coefficient of the third resistor
The number is different from the first and second resistors and the difference
Offset component with positive temperature characteristic by dynamic amplifier
Generates offset components with negative temperature characteristics that almost cancel
It has the size to be.

According to the first aspect of the present invention, the offset voltage of the comparator circuit is predetermined based on the first to third constant current circuits. A comparison input signal is supplied to each base terminal of the first and second transistors, and when the comparison input signal changes and the current ratio flowing through the first and second transistors becomes equal to or higher than a predetermined ratio, the third constant current circuit outputs, for example, A binary high-level comparison output signal is output. On the other hand, when the difference between the comparison input signals is zero, the third constant current circuit outputs, for example, a binary low-level comparison output signal.

The offset voltage has an offset component having a positive temperature characteristic and an offset component having a negative temperature characteristic. An offset component having a positive temperature characteristic is generated by a differential amplifier. On the other hand, the offset components having negative temperature characteristics are the first to third components described above.
It is generated based on the temperature coefficient of the resistance value of the resistor.

That is, the temperature coefficient of the third resistor is:
Different from the first and second resistors and the differential amplifier
Offset component with positive temperature characteristics due to the heater
Large offset component having a negative temperature characteristic
Off, which has bipolar temperature characteristics
The set components substantially cancel each other out, thereby reducing the ambient temperature
The offset voltage is kept almost constant regardless of
Then, a stable and accurate comparison operation is performed.

Therefore, as compared with the conventional case where the offset voltage consists only of the offset component having the positive temperature characteristic, the offset voltage due to the change in the ambient temperature is reduced by the offset component having the negative temperature characteristic. Voltage fluctuation is suppressed, and the temperature characteristics of the offset voltage are improved as a whole.

For this reason, even if the ambient temperature is lowered, the offset voltage having a negative temperature characteristic improves the temperature characteristic of the offset voltage. Can be avoided reliably.
For example, even at a low temperature, the offset voltage can be prevented from decreasing, and the margin for noise does not change, so that the reliability of the comparator circuit is significantly improved.

In addition, the emitter of the first and second transistors
The first and second resistors connected to the
Because it has a temperature coefficient, the first resistor
Combination of temperature coefficients of two types of resistors out of the third resistor
You only need to consider This greatly simplifies circuit design.
Can be simplified.

According to a second aspect of the present invention, there is provided a comparator circuit according to the first aspect , wherein the comparator circuit is formed on an integrated circuit.
In this case, the above-described first to third resistors are replaced with ion implantation resistors.
Each of the resistors is connected to the high temperature side
If the temperature coefficient is different on the low temperature side,
The temperature coefficient is the temperature coefficient of each resistor.
You.

According to the second aspect of the present invention, in addition to the effect based on the first aspect of the present invention, the temperature coefficient of the resistance is high.
Even if it has an inflection point that is different between the side and the low temperature side,
By making each temperature coefficient on the low temperature side the temperature coefficient of resistance
Therefore, the fluctuation of the offset voltage on the low temperature side can be reliably reduced.
Wear.

The comparator circuit according to the third aspect of the present invention
The infrared remote control device provided comprises:
Or a comparator circuit having the invention specifying items described in 2.
Have.

According to the third aspect of the present invention, the infrared remote control
The control device is an invention specifying matter according to claim 1 or 2
A comparator circuit that operates based on
Ambient temperature, which has been a problem in the past.
Can reliably avoid fluctuations in temperature or malfunction due to low temperature
You.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows a comparator circuit according to this embodiment.
As shown in FIG.
1 and Q2, and the comparison input signals _Vin1 and _Vin2 are input to the respective base terminals. Transistor Q
The collector terminals of Q1 and Q2 are connected to transistors Q3 and Q4
Are connected respectively to the collector terminals. Each of the transistors Q3 and Q4 has an emitter terminal connected to the _Vcc line (the positive potential of the power supply).

The transistor Q3 has a base terminal and a collector terminal connected to each other, and is further connected to a base terminal of the transistor Q5, so that the transistor Q3 and the transistor Q5 form a current mirror circuit (first constant current circuit). I do. The transistor Q4 has a base terminal and a collector terminal connected to each other, and is further connected to a base terminal of the transistor Q6, so that the transistor Q4 and the transistor Q6 form a current mirror circuit (second constant current circuit).

The collector terminal of the transistor Q5 is connected to the collector terminal of the transistor Q7. The emitter terminal of the transistor Q7 is connected to a ground line (ground potential of a power supply). Transistor Q7
The transistor Q7 and the transistor Q8 form a current mirror circuit (third constant current circuit) by connecting the base terminal and the collector terminal and further connecting the base terminal of the transistor Q8.

The collector terminal of the transistor Q6 is connected to the collector terminal of the transistor Q8. The emitter terminal of the transistor Q8 is connected to the ground line. The comparison output signal V _out is output from the collector terminal of the transistor Q8. Transistors Q5, Q
The 6 emitter terminals are each connected to the V _CC line. The transistors Q7 and Q8 have their base terminals connected to each other, and their emitter terminals connected to the ground line.

The emitter terminal of the transistor Q1 is
It is connected to one end of a resistor R1 (first resistor). on the other hand,
The emitter terminal of the transistor Q2 is connected to one end of a resistor R2 (second resistor). The other ends of the resistors R1 and R2 are connected to each other, and the connection point is connected to the collector terminal of the transistor Q9. The transistor Q9 has an emitter terminal connected to the ground line and a base terminal connected to the base terminal of the transistor Q11.

The transistor Q11 has a collector terminal and a base terminal connected to each other, and is further connected to the base terminal of the transistor Q9, so that the transistor Q9 and the transistor Q11 are connected to a current mirror circuit (fourth constant current circuit). ). This transistor Q1
1 has an emitter terminal connected to the ground line. The collector terminal of the transistor Q11 is connected to a resistor R3
(Third resistor) is connected to the emitter terminal of the transistor Q10. The transistor Q10 has a collector terminal and a base terminal connected to each other, and functions as a diode. The collector terminal of the transistor Q10 is connected to the V _CC line.

The resistor R3 is provided for supplying a bias current of the differential amplifier. Resistance R
1, R2, and R3 each have a temperature coefficient that generates an offset component having a negative temperature characteristic at the offset voltage.

[0035] In the above structure, while the comparison input signal V _in1 to the base terminal of the transistor Q1 is input, compares the input signal V _in2 to the base terminal of the transistor Q2 is inputted. When V _in1 = V _in2 , the comparison output signal V _out has a binary low level. On the other hand, the comparison input signals _Vin1 and _Vin2 change, and the transistors Q1 and Qin
When the currents I ₁ and I ₂ flowing through 2 satisfy I ₂ / I ₁ ≧ 2, the comparison output signal V _out changes to the binary high level.

Here, transistors Q1, Q2, Q1
0 and the base-emitter voltage of Q11 are V
_BE1, V _BE2, V _BE10, and a V _BE11, a Boltzmann constant and k, absolute temperature is T, when the charge and q, the following equation is established.

I ₁ : I ₂ = 1: 2 (6) I ₁ + I ₂ = I ₃ = (V _CC −V _BE10 −V _BE11 ) / R3 (7) V _in1 −V _BE1 − (R1 × I ₁ ) = V _in2 −V _BE2 − (R2 × I ₂ ) (8) V _BE1 = (kT / q) ln (I ₁ / I ₀ ) (9) V _BE2 = (kT / q ) Ln (I ₂ / I ₀ ) (10) From the above equation, the offset voltage ΔV of the comparator circuit is
The following equation (11) is obtained.

ΔV = V _in2 −V _in1 = V _BE2 + (R2 × I ₂ ) −V _BE1 − (R1 × I ₁ ) = (R2 × I ₂ −R1 × I ₁ ) + (V _BE2 −V _BE1 ) = (2 · R2-R1) I 3/3 + (kT / q) ln2 ...... (11) where the first term of [Delta] V and _{ΔV 1, V 0 = (V} CC -V
_BE10 - _VBE11 ), the following equation (12) is established from (7).

ΔV ₁ = (2 · R2−R1) · V ₀ / (3 · R3) (12) Assuming that the second term of the offset voltage ΔV is ΔV ₂ , ΔV ₂
Is generated by the differential amplifier described above. (11) above
As is apparent from the equation, ΔV ₂ is (kT / q) +3.
Since it is known to have a temperature coefficient of 300 (ppm / K), it represents an offset component having a positive temperature characteristic.

On the other hand, ΔV ₁ is equal to the resistance R1,
The offset component is generated based on the combination of the temperature coefficients of R2 and R3. If the combination of the temperature coefficients of the resistors R1, R2 and R3 is appropriately selected, the offset component having the negative temperature characteristic as described above is obtained. Can be realized. As described above, the presence of the offset component ΔV ₁ having a negative temperature characteristic allows the offset voltage to be reduced by the amount corresponding to the existence of ΔV ₁ as compared with the conventional case where the offset voltage includes only the offset component having the positive temperature characteristic. The change in the offset voltage due to the temperature change is suppressed, and the temperature characteristics of the offset voltage are improved as a whole.

Therefore, even if the ambient temperature changes and the temperature becomes low, the temperature characteristic of the offset voltage is improved by the presence of ΔV _1. Can be avoided. This is because it is possible to avoid the offset voltage from being reduced due to the presence of ΔV ₁ , whereby the margin for noise does not change, thereby significantly improving the reliability of the comparator circuit.

By the way, the above-described resistors R1 and R2
Preferably have the same temperature coefficient. In this case, since only the combination of the two temperature coefficients of the resistors R1, R2, and R3 needs to be considered in circuit design, the circuit design can be greatly simplified.

The temperature coefficients which generate the offset component (ΔV ₁ ) having the negative temperature characteristic which substantially cancels the offset component (ΔV ₂ ) having the positive temperature characteristic by the differential amplifier are set to the resistances R1, R2, and R3. It is more preferable that each has, in this case, the action as shown below,
It works.

That is, for example, the resistors R1, R2, and R3 have a temperature coefficient represented by the following equations (a) and (b) with respect to an ambient temperature of low temperature T ≦ 273 K (0 ° C.). Suppose you have

DR1 / dT = dR2 / dT = + 100 (ppm / K) (a) dR3 / dT = + 3500 (ppm / K) (b) That is, both the resistors R1 and R2 have a low temperature T ≤273K
+100 ppm / K for an ambient temperature of (0 ° C.)
The above-mentioned resistance R3 has a temperature coefficient T ≦ T.
+3500 for an ambient temperature of 273K (0 ° C.)
Assume that it has a temperature coefficient of ppm / K.

Here, _assuming that R2 = R1 = R and V _BE10 + V _BE11 = 2V _BE for convenience of explanation, the above (11) is expressed by the following equation (13).

ΔV = (R / 3R3) (V _CC −2V _BE ) + (kT / q) ln2 (13) As is apparent from the above equation (13), the offset voltage Δ
The second term [Delta] V ₂ of V is, (kT / q) is +3300 (pp
m / K) is known.
Represents an offset component having a positive temperature characteristic.

On the other hand, the first offset voltage ΔV
The term ΔV ₁ represents an offset component having a negative temperature characteristic. This is for the following reason. That is, as is clear from the above (a) and (b), (R / R3) is
This is because it has a temperature coefficient of (+ 100 / + 3500) (ppm / K), and thus has a temperature coefficient of −3400 (ppm / K) substantially.

As described above, the offset voltage ΔV is equal to the positive temperature coefficient of the second term ΔV ₂ (+3300 (ppm /
K)) is the negative temperature coefficient of the first term ΔV ₁ (−3400
(Ppm / K)). Due to this cancellation, as shown by the solid line in FIG. 2, fluctuations in the offset voltage due to changes in the ambient temperature are suppressed, and the temperature characteristics of the offset voltage are improved as a whole. Since the positive temperature coefficient of the second term ΔV ₂ is almost always canceled by the negative temperature coefficient of the first term ΔV ₁ , the offset voltage, which conventionally decreases with a decrease in the ambient temperature, is reduced regardless of the temperature. It becomes substantially constant (both in the low temperature range and the high temperature range) (see the characteristics shown by the solid line in FIG. 2). Therefore, the offset voltage can be kept substantially constant irrespective of the temperature, and the margin for noise does not change, so that the reliability of the comparator circuit is significantly improved.

As described above, even if the ambient temperature changes, the offset components having bipolar temperature characteristics are almost always offset each other.
A stable and accurate comparison operation is performed.

Here, in the temperature characteristic,
A case where the inflection point has a temperature coefficient different between the high temperature side and the low temperature side will be described.

As a case having an inflection point, there is a case where the above-mentioned comparator circuit is formed on an integrated circuit by using a separation process by ion implantation resistance. In this case, the temperature coefficient of the resistance is different between the high temperature side and the low temperature side. Therefore, by using each temperature coefficient on the low temperature side as the temperature coefficient of each resistor, even if the temperature coefficient of the resistance has an inflection point different between the high temperature side and the low temperature side, the fluctuation of the offset voltage on the low temperature side Can be reliably reduced.

Next, a case where the above-described comparator circuit is used in an infrared remote control device will be described with reference to FIGS.

As shown in FIG. 3, the infrared remote control device of the present embodiment includes a comparator circuit 1 having the above-described features.

FIG. 3 shows an infrared remote control device.
As shown in FIG. The photodiode 2 receives an infrared light signal (see FIG. 4 (a)) which is normally modulated at 38 kHz and further coded with or without a carrier wave, converts the infrared light signal into an electric signal, and amplifies the signal. Send to block 3.

The amplifier block 3 comprises, for example, two amplifiers and a coupling capacitor C1 for AC-coupling these amplifiers. Amplifier block 3
Amplifies the input electric signal with a predetermined amplification factor (see FIG. 4).
(See (b)), and is sent to the bandpass filter 4 via the coupling capacitor C2.

The band-pass filter 4 is set so that the intensity-modulated frequency (normally 38 kHz) coincides with the center frequency, and a signal in a predetermined band including the center frequency is amplified here (FIG. 4 ( c) See the waveform indicated by the solid line in FIG. The output of the bandpass filter 4 is sent to a detection level generation circuit 5, where a detection level is generated (FIG. 4).
(See the waveform indicated by the broken line in (c)), and is sent to the comparator circuit 1 as the comparison input signal _Vin1 . The output of the band-pass filter 4 is also equal to the comparison input signal V
_It is sent to the comparator circuit 1 as _in2 .

The comparator circuit 1 extracts the modulation frequency component, integrates it with an integrator (not shown) including the capacitor C3 (see FIG. 4D), and sends it to the hysteresis comparator 6. Hysteresis comparator 6
Performs waveform shaping of the extracted modulation frequency component based on the threshold level, and outputs the waveform through the transistor 7 (see FIG. 4E).

Since the infrared remote control device includes the comparator circuit 1, as described above, the preset offset voltage (see the offset voltage ΔV in FIG. 4C) affects the temperature fluctuation. Therefore, even if the ambient temperature changes to a low temperature, it is possible to surely avoid a malfunction caused by a decrease in the ambient temperature as in the related art. This corresponds to the above ΔV ₁
The reason for this is that the offset voltage can be reliably prevented from being reduced due to the presence of, so that the margin for noise does not change, so that the reliability of the comparator circuit 1 is significantly improved.

The present invention is not limited to the above embodiment, and various modifications can be made within the scope of the present invention. For example, in the above-described embodiment, the case where the positive temperature coefficient of ΔV ₂ is substantially offset by the negative temperature coefficient of ΔV ₁ has been described. However, the present invention is not limited to this. What is necessary is just a temperature coefficient which can be ignored. Of course, a temperature coefficient that can be completely canceled may be used.

In the above embodiment, the case where the ratio of currents I ₁ and I ₂ flowing through transistors Q 1 and Q ₂ is 1: 2 has been described as an example, but the present invention is not limited to this. is not.

[0062]

As described above, the comparator circuit according to the first aspect of the present invention has the following advantages. (1) One end is connected to the emitter terminals of the first and second transistors and the other end is connected to each other. A first and a second resistor, and (2) a bias current for a differential amplifier connected to the above-mentioned connection point of the first and the second resistor and including a third resistor and limited by the third resistor. And a fourth constant current circuit .
The first resistor and the second resistor have the same temperature coefficient, and
The temperature coefficient of the third resistor is different from that of the first and second resistors.
Different and has positive temperature characteristics due to the above differential amplifier
Having a negative temperature characteristic that almost offsets the offset component
It is characterized by having a size that generates a fset component .

Therefore, as compared with the conventional case where the offset voltage includes only the offset component having the positive temperature characteristic, the offset voltage accompanying the change in the ambient temperature is reduced by the offset component having the negative temperature characteristic. And the temperature characteristics of the offset voltage can be improved as a whole.

For this reason, even if the ambient temperature is lowered, the offset voltage having a negative temperature characteristic can be prevented from decreasing due to the offset component, and the margin for noise does not change. Can be significantly improved.

Further, even if the ambient temperature changes to a low temperature, the temperature characteristic of the offset voltage is improved due to the presence of the offset component having a negative temperature characteristic. Malfunction due to low temperature can be reliably avoided.

Therefore, even if the ambient temperature changes
However, there is always an offset component having bipolar temperature characteristics.
Almost offset each other, regardless of ambient temperature,
A stable and accurate comparison operation is performed.

In addition, the emitter of the first and second transistors
The first and second resistors connected to the
Because it has a temperature coefficient, the first resistor
Combination of temperature coefficients of two types of resistors out of the third resistor
You only need to consider This greatly simplifies circuit design.
It also has the effect that it can be simplified.

According to the second aspect of the present invention , as described above, when the comparator circuit is formed on an integrated circuit according to the first aspect of the present invention ,
The first to third resistors are separated by ion implantation resistors.
Each resistance is different between the high temperature side and the low temperature side.
Each temperature coefficient on the low temperature side
It is characterized by a temperature coefficient of resistance.

Therefore, based on the invention specifying matter of claim 1,
In addition to the effect, the temperature coefficient of resistance
Even if it has different inflection points, each temperature on the low temperature side
By using the temperature coefficient as the temperature coefficient of the resistance,
The effect that the fluctuation of the offset voltage can be surely reduced
Play together.

The infrared remote controller according to the third aspect of the present invention.
The trawl device is an invention specifying matter according to claim 1 or 2.
Characterized by having a comparator circuit having
ing.

Therefore, the invention is specified in claim 1 or 2.
Equipped with a comparator circuit that produces effects based on terms
Therefore, when the temperature coefficient has an inflection point, it becomes a problem in the past.
Malfunctions caused by lowering the ambient temperature
The effect is also achieved.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration example of a comparator circuit of the present invention.

FIG. 2 is an explanatory diagram showing the ambient temperature dependence of an offset voltage in a conventional comparator circuit and a comparator circuit of the present invention.

FIG. 3 is an explanatory diagram showing a configuration example when the comparator circuit is employed in an infrared remote control device.

FIG. 4 is a waveform chart showing waveforms at various parts in FIG.

FIG. 5 is a circuit diagram illustrating a configuration example of a conventional comparator circuit.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 comparator circuit 2 photodiode 3 amplifier block 4 bandpass filter 5 detection level generation circuit Q1 transistor Q2 transistor R1 resistor (first resistor) R2 resistor (second resistor) R3 resistor (third resistor)

Claims (3)

(57) [Claims] 1. A differential amplifier comprising first and second transistors each having a base terminal supplied with a comparison input signal, and first and second transistors respectively connected to the collector terminals of the first and second transistors. A second constant current circuit, and a third constant current circuit connected to the first and second constant current circuits and outputting a comparison output signal, wherein an offset voltage is set based on the first to third constant current circuits. A predetermined comparator circuit, wherein one end is connected to the emitter terminal of each of the first and second transistors, and the other end is connected to the first and second resistors; Connected to the above connection point of the resistor,
A fourth constant current circuit including a third resistor for supplying a bias current of the differential amplifier limited by the third resistor , wherein the first resistor and the second resistor have the same temperature coefficient; And
The temperature coefficient of the third resistor is equal to the first and second resistances.
Different from the resistance, the positive temperature characteristic
Negative temperature characteristics that almost cancel the offset component
A comparator circuit having a magnitude that generates an offset component having the same. 2. The method according to claim 1, wherein the comparator circuit is formed on an integrated circuit.
In this case, the above-described first to third resistors are replaced with ion implantation resistors.
Each of the resistors is connected to the high temperature side
If the temperature coefficient is different on the low temperature side,
The temperature coefficient of each resistor is used as the temperature coefficient.
The comparator circuit according to claim 1. 3. The comparator circuit according to claim 1, wherein:
Infrared remote control device with.