JP2000077950A - Stabilized current source and data receiving circuit - Google Patents

Abstract

(57) [Summary] A stabilized current source and a data receiving circuit are provided.
Provided is a stabilized current source in which a supply current does not fluctuate with respect to a temperature fluctuation, and a data receiving circuit to which the stabilized current source is applied. SOLUTION: A current of a first stabilized current source, which is stable against a power supply voltage fluctuation and has a positive temperature coefficient against a temperature fluctuation, is stable against a power supply voltage fluctuation, and is stable against a temperature fluctuation. On the other hand, the current of the second stabilized current source having a negative temperature coefficient is configured to be added at a specific ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stabilized current source and a data receiving circuit, and more particularly to a stabilized current source having a small variation in supply current with respect to a temperature variation and supplying a bias current from the stabilized current source. The present invention relates to a data receiving circuit whose output amplitude is stable with respect to received temperature fluctuation.

Generally, it is necessary to assume that power supply voltage fluctuation of an external power supply applied to a communication device such as an optical transmitting / receiving device is about ± 10%. That is, a power supply voltage that can fluctuate by about ± 10% is supplied to the communication device.

[0003] In addition, a wide range of ambient temperature fluctuation (usually in the range of about -40 ° C to + 100 ° C) is assumed depending on the installation conditions of the communication device. Therefore, the ambient temperature of the electronic circuit constituting the communication device also fluctuates in this range.

[0004] A communication device is required to operate stably even when there is a fluctuation in external power supply or a fluctuation in ambient temperature as described above. On the other hand, there is a strong demand from customers for miniaturization and cost reduction of communication devices, and since it is essential for manufacturers to improve mass productivity, it is desired to promote the integration of communication devices into integrated circuits.

Therefore, it is essential to develop an integrated circuit that operates stably against external power supply fluctuations and ambient temperature fluctuations. To this end, the bias current or bias voltage inside the integrated circuit is reduced by external power supply fluctuations and ambient temperature fluctuations. Need to stabilize against fluctuations.

[0006]

2. Description of the Related Art FIG. 9 shows a configuration example (part 1) of a conventional stabilized current source, in which a circuit usually called a V _BE multiplier (V _BE is a voltage between a base and an emitter of a transistor) is biased. This is the type that the circuit has.

In FIG. 9, reference numeral 11 denotes a transistor;
Are resistors, and these constitute a current source 10.
Further, 21 is a transistor, 22 to 24 are resistors, and these constitute a V _BE multiplier type bias circuit 20.

Reference numeral 50 denotes a load circuit (shown simply as a load in the figure) which receives a bias current from the current source 10. Here, the base-emitter voltage of each transistor is marked with V _BE with the number of the sign of the transistor, the resistance of each resistor is marked with R, and the number of the sign of the resistance is marked on R. If title, the bias current I ₁ of the current source 10 is given by the following equation.

I ₁ = (V _BE21 (1 + R ₂₃ / R ₂₄ ) −V _BE11 ) / R ₁₂ Now, when the circuit of FIG. 9 is formed of an integrated circuit, all transistors have the same shape if the transistors have the same shape. Have substantially the same value (this is generally referred to as V _BE ), so that I ₁ can be approximated by the following equation.

I ₁ = V _BE · R ₂₃ / (R ₂₄ · R ₁₂ ) (1) As is apparent from equation (1), the current I ₁ is independent of the power supply voltage V _EE, and Transistor base
The emitter-to-emitter voltage is basically independent of the power supply voltage. Therefore, the current supplied by the current source of FIG. 9 is stable against voltage fluctuation of the external power supply.

FIG. 10 shows a configuration example (part 2) of a conventional stabilized current source, in which a bias circuit has a circuit called a diode stacked type in the present invention. In FIG. 10, 11 is a transistor, 12 is a resistor, and these constitute a current source 10.

Reference numerals 31 and 32 denote transistors, and reference numerals 33 to 35 denote resistors. These constitute a diode-stacked bias circuit 30. Reference numeral 50 denotes a load circuit.

[0013] Here, the base-emitter voltage of each transistor, and the title are assigned the numbers sign of the transistor V _BE, the resistance value of each resistor, the number of the resistor symbols in R When subjected to to title, its terminal voltage transistor 31 and the transistor 32 is being diode connected from equal to the base-emitter voltage, the bias current I ₂ of the current source 10 is given by the following equation.

I ₂ = (R ₃₅ (V _BE31 + V _BE32 ) / (R ₃₄ + R ₃₅ )
− V _BE11 ) / R ₁₂ Again, the base of all transistors in the integrated circuit
Considering that the emitter-to-emitter voltage is substantially constant, I ₂ is approximated by the following equation.

I ₂ = (R ₃₅ −R ₃₄ ) · V _BE / (R ₃₄ + R ₃₅ ) · R ₁₂ (2) Therefore, the current supplied by the current source in FIG. 10 is also stable against the voltage fluctuation of the external power supply. It is.

FIG. 11 shows a configuration example (part 3) of a conventional stabilized current source, which is a type having a circuit generally called a band gap reference type in a bias circuit. In FIG. 11, 11 is a transistor, 12 is a resistor, and these constitute a current source 10.

Reference numerals 41 to 43 denote transistors, and reference numerals 44 to 47 denote resistors. These components constitute a band gap reference type bias circuit 40. The transistor 41 has a collector and a base short-circuited and is diode-connected. Although the transistor 42 is labeled as a single transistor, a plurality of transistors (N: N is a positive integer) are actually connected in parallel.

Reference numeral 50 denotes a load circuit. here,
The base-emitter voltage of each transistor is V _BE
Are denoted by the numerals of the transistors, and the resistance values of the respective resistors are denoted by R, and the numbers of the resistors are denoted by R.
Form a current mirror, the current I ₃ of the current source 10 is given by the following equation. Here, _VR45 is a voltage drop generated in the resistor 45.

I ₃ = (V _BE41 + V _R45 −V _BE11 ) / R ₁₂ Again, the base of all transistors in the integrated circuit
When emitter voltage Considering that is substantially constant, the I ₃ is approximated by the following equation.

I ₃ = V _R45 / R ₁₂ Now, the resistances of the resistor 45 and the resistor 46 are made equal,
Assuming that the base-emitter voltage of the transistor 41 is equal to the base-emitter voltage of the transistor 43 and considering that the transistor 42 is formed by connecting N transistors of the same dimension as the transistor 41 in parallel, the base-emitter voltage of the transistor is , Thermal voltage V _T = kT / q
(K is the Boltzmann constant, T is the absolute temperature, q is the charge of the electron), the collector current I _C of the transistor, and the reverse collector saturation current I _{S of} the transistor. V _BE = V _T ln (I _C / I _S ), I ₃ = (R ₄₅ / (R ₄₇ · R ₁₂ )) V _T ln N (3)
Becomes

Therefore, the current supplied by the current source shown in FIG. 11 is also stable against the voltage fluctuation of the external power supply. FIG. 12 shows an example of the configuration of a conventional data receiving circuit, in which a stabilizing current source of the type provided in the diode-stacked bias circuit of FIG. 2 is applied.

In FIG. 12, reference numeral 11 denotes a transistor, 1
Reference numeral 2 denotes a resistor, and these constitute a current source 10.
Reference numerals 31 and 32 denote transistors, and reference numerals 33 to 35 denote resistors. These constitute a diode-stacked bias circuit 30.

Further, 51 and 52 are transistors, 53
And 54, resistors, which constitute the load circuit 50. The current source 10, the diode-stacked bias circuit 30, and the load circuit 50 constitute a data receiving circuit.

In the data receiving circuit of FIG. 12, the bases of the transistors 51 and 52 are used as input terminals, and the collectors of the transistors 51 and 52 are used as output terminals.

When the base potential of the transistor 51 is higher than the base potential of the transistor 52 due to the input data, all the collector current of the transistor 11 constituting the current source 10 flows through the transistor 51, Is lower than the collector potential of the transistor 52.

Conversely, when the base potential of the transistor 52 is higher than the base potential of the transistor 51 due to the input data, all the collector current of the transistor 11 constituting the current source 10 flows through the transistor 52, The collector potential of the transistor 52 is lower than the collector potential of the transistor 51.

That is, the transistor 11 operates so that the collector current of the transistor 11 is switched between the transistor 51 and the transistor 52 according to the input data.
Is referred to as a current switch type data receiving circuit.

Note that input data is not applied between two bases (this is called a balanced type), but is applied to one base and the other base is fixed at a reference potential (this is called unbalanced). There is also a usage (this is called an unbalanced type) in which output data is output from only one collector without being output from two collectors (this is called a balanced type). There is also a method of using one of the input and the output as a balanced type and the other as an unbalanced type.

In the current switch type data receiving circuit, the current of the transistor 11 constituting the current source 10 is switched, so that the stability of the amplitude of the output data depends on the stability of the current of the current source 10. .

The stabilized current source applied here is shown in FIG.
Since the transistor has the configuration of 0, the current of the transistor 11 constituting the current source does not depend on the voltage of the external power supply. Therefore, the output amplitude of the data receiving circuit having the configuration shown in FIG. 12 is stable without depending on the voltage of the external power supply.

Here, the data receiving circuit in which the stabilized current source having the configuration shown in FIG. 10 is combined with the load circuit is illustrated. However, the data receiving circuit having the configuration shown in FIGS. 9 and 11 may be combined with the load circuit. Thus, a data receiving circuit having a stable output amplitude can be obtained.

[0032]

As described above, since the current of the stabilized current source shown in FIGS. 9 to 11 does not depend on the voltage of the external power supply, it is not affected by the voltage fluctuation of the external power supply.

However, the currents I ₁ and I ₂ in the equations (1) and (2) include the base-emitter voltage V
_BE is included. As is well known, the base-emitter voltage V _BE of the transistor varies at −2 mV / ° C.

Therefore, the current I _{1 of the} equations (1) and (2)
Or I ₂ varies by variations in ambient temperature accordingly. Since it is necessary to assume that the ambient temperature fluctuates over a wide range, the fluctuations of the currents I ₁ and I ₂ in Equations (1) and (2) due to temperature changes cannot be ignored.

Further, the current I ₃ in the equation (3) includes the absolute temperature T, and similarly, the fluctuation of the current I ₃ in the equation (3) accompanying the temperature change cannot be ignored. The output amplitude of the data receiving circuit to which such a stabilized current source is applied also fluctuates in response to the fluctuation of the currents I _{1 to} I ₃ in Equations (1) to (3) due to a temperature change.

In view of the above problems, the present invention provides a stabilized current source capable of supplying a stable current even when the ambient temperature fluctuates, and an output amplitude of the stabilized current source by applying the stabilized current source. An object of the present invention is to provide a data receiving circuit that is stable against temperature fluctuations.

[0037]

As can be seen from the above equations (1) and (2), a current I ₁ of a stabilized current source having a V _BE multiplier type bias circuit and a diode stacked type bias circuit are provided. At the current I ₂ of the stabilized current source, the coefficient of the base-emitter voltage V _BE is positive.

Since the base-emitter voltage V _BE varies at a rate of −2 mV / ° C., the current I ₁ of the stabilized current source having the V _BE multiplier type bias circuit and the diode stacked type bias circuit are used. current I ₂ of the regulated current source with has a negative temperature coefficient.

On the other hand, since the absolute temperature T is included in the current I ₃ of the stabilized current source having the band gap reference type bias circuit, the temperature coefficient of the current I ₃ is positive.

The first invention has been made in view of the above facts, and comprises a stabilized current source having a band gap reference type bias circuit, a V _BE multiplier type bias circuit or a diode stacked type. And a stabilizing current source that combines the currents of the stabilizing current sources provided with the bias circuits.

According to the first invention, the band gap
The temperature coefficient of the current of the stabilized current source with the reference type bias circuit is positive, and the temperature coefficient of the current of the stabilized current source with the V _BE multiplier type bias circuit or the diode stacked type bias circuit is negative. Therefore, by appropriately setting the resistance values appearing in the above equations (1) and (3), it is possible to cancel out the temperature coefficients of the two,
The temperature coefficient of the coupled current can be suppressed.

The second invention has also been made in view of the above facts, and comprises an output voltage of a band gap reference type bias circuit, a V _BE multiplier type bias circuit or a diode stacked type bias circuit. Is a stabilized current source provided with a bias circuit configured to combine the output voltages of the above.

According to the second invention, the band gap
The temperature coefficient of the output voltage of the reference type bias circuit is positive, and the temperature coefficient of the output voltage of the V _BE multiplier type bias circuit or diode stacked type bias circuit is negative. By doing so, both temperature coefficients can be canceled out, and therefore, the temperature coefficient of the current of the stabilized current source can be suppressed.

A third invention is a data receiving circuit to which the stabilized current source obtained by the first invention or the second invention is applied. According to the third invention, since the temperature coefficient of the current of the stabilized current source obtained by the first invention or the second invention is small, it is possible to suppress the temperature coefficient of the output amplitude of the data receiving circuit, A data receiving circuit that is stable against temperature fluctuations can be obtained.

[0045]

FIG. 1 shows a first embodiment of a stabilized current source according to the present invention. The stabilized current source includes a band gap reference type bias circuit and a V _BE multiplier type. 3 shows a stabilized current source that combines currents of a stabilized current source with a bias circuit. In FIG.
11 is a transistor, 12 is a resistor, and these constitute a current source 10, and 11a is a transistor, 12
a is a resistor, and these constitute a current source 10a. Then, the output currents of the current source 10 and the current source 10a are coupled to each other.

Reference numeral 21 denotes a transistor, and reference numerals 22 to 24 denote resistors. These constitute a V _BE multiplier type bias circuit 20, and its output voltage is supplied to the current source 10a. Reference numerals 41 to 43 denote transistors, and reference numerals 44 to 47 denote resistors. These constitute a band-gap reference type bias circuit 40, whose output voltage is supplied to the current source 10.

Reference numeral 50 denotes the current source 10 and the current source 1
0a is a load circuit which receives supply of a bias current from 0a (in the figure, simply referred to as a load). Since the output currents of the current source 10 and the current source 10a are coupled to each other,
Regulated current source of the current configuration of FIG. 1 is a current obtained by adding the current I ₁ given by the formula current I ₃ given by (3) and the formula (1).

Now, the coefficient of the absolute temperature T at the current I ₃ of the stabilized current source having the band gap reference type bias circuit is (R ₄₅ / (R ₄₇ · R ₁₂ )) (k / q) ln N. This is referred to as k _3.

On the other hand, the coefficient of V _BE at the current I ₁ of the current source having the V _BE multiplier type bias circuit is R ₂₃ / (R ₂₄ · R _12a ). This is referred to as k _1.

Therefore, if the resistance value is set so that the absolute value of the product of the coefficient k ₁ and the rate of change of the absolute temperature and the product of the coefficient k ₃ and the rate of change of the base-emitter voltage are equal, The current of the stabilized current source having the configuration 1 does not fluctuate due to a temperature change.

FIG. 2 shows a stabilized current source according to a second embodiment of the present invention. The stabilized current source includes the diode-stacked bias circuit and the band-gap reference bias circuit. 3 shows a stabilized current source that combines the currents of the stabilized current sources.

In FIG. 2, reference numeral 11 denotes a transistor;
Are resistors, and these constitute a current source 10 and 11
a is a transistor, 12a is a resistor, and these constitute a current source 10a. Then, the output currents of the current source 10 and the current source 10a are coupled to each other.

31 and 32 are transistors, 33 to 3
Reference numeral 5 denotes a resistor, which constitutes a diode-stacked bias circuit 30, and the output voltage of which is supplied to the current source 10a. Reference numerals 41 to 43 denote transistors, and reference numerals 44 to 47 denote resistors. These constitute a band-gap reference type bias circuit 40, whose output voltage is supplied to the current source 10.

Reference numeral 50 denotes the current source 10 and the current source 1
0a is a load circuit which receives supply of a bias current from 0a (in the figure, simply referred to as a load). Since the output currents of the current source 10 and the current source 10a are coupled to each other,
The current of the stabilized current source having the configuration of FIG. 2 is a current obtained by adding the current I ₃ given by the above equation (3) and the current I ₂ given by the above equation (2).

Now, the coefficient of the absolute temperature T at the current I ₃ of the stabilized current source having the band gap reference type bias circuit is R ₄₅ / (R ₄₇ · R ₁₂ ) (k / q) as described above. In ln N, we set this as k ₃ .

On the other hand, the coefficient of V _BE at the current I ₂ of the current source having the diode-stacked bias circuit is (R ₃₅ −R ₃₄ ) / (R ₃₄ + R ₃₅ ) · R ₁₂ . This is referred to as k _2.

Here, (R₃₅−R₃₄), But the
Under the condition that current flows through the transistor 11a,
Must. That is, the coefficient k_TwoIs positive. Subordinate
The coefficient k_TwoAnd the rate of change of base-emitter voltage
Product and its coefficient k_ThreeAnd the absolute value of the product of the rate of change of absolute temperature
If you set the above resistance value so that _TwoOf the configuration
The current of the regulated current source does not fluctuate due to temperature changes.
You.

FIG. 3 shows a third embodiment of the stabilized current source according to the present invention, in which an external resistor is added to the configuration of FIG. In FIG. 3, 11 is a transistor, 12 is a resistor,
Reference numeral 13 denotes a resistor externally added so as to be connected in parallel with the resistor 12, and these constitute a current source 10;
11a is a transistor, 12a is a resistor, 13a is a resistor added externally so as to be connected in parallel to the resistor 12a, and these constitute a current source 10a. Then, the output currents of the current source 10 and the current source 10a are coupled to each other.

31 and 32 are transistors, 33 to 3
Reference numeral 5 denotes a resistor, which constitutes a diode-stacked bias circuit 30, and the output voltage of which is supplied to the current source 10a. Reference numerals 41 to 43 denote transistors, and reference numerals 44 to 47 denote resistors. These constitute a band-gap reference type bias circuit 40, whose output voltage is supplied to the current source 10.

Reference numeral 50 denotes the current source 10 and the current source 1
0a is a load circuit which receives supply of a bias current from 0a (in the figure, simply referred to as a load). With such a configuration, the resistance value of a resistor connected to the emitter of the transistor 11 and the emitter of the transistor 11a can be arbitrarily adjusted. That is, the ratio of the current between the current source 10 and the current source 10a can be arbitrarily adjusted.

As a result, the temperature dependence of the current of the stabilized current source having the configuration shown in FIG. 3 can be arbitrarily adjusted.
V _BE with temperature variations in the regulated current source of the configuration of FIG. 3
Can be adjusted arbitrarily.

The advantage of this configuration is that the stabilized power of the configuration of FIG.
Reduce the effect of current changes due to temperature fluctuations in the source
Design can be made easier. That is,
Number k _TwoAnd the rate of change of base-emitter voltage
Number k_ThreeAnd the absolute value of the product of the rate of change of absolute temperature
Is not always easy due to the large number of resistors involved
But also to obtain accurate resistance values in integrated circuits.
And the coefficient k as designed_TwoAnd coefficient k_Three
Is difficult to obtain, but it can be adjusted by adding an external resistor
By doing so, the coefficient k as designed_TwoAnd coefficient k_Three
Is easier to obtain.

In this embodiment, two external resistors are connected in parallel to the resistor 12 and the resistor 12a. However, the two external resistors are connected to the resistor 12 and the resistor 12a, respectively.
It is also possible to adopt a configuration in which a is connected in series to a.

FIG. 3 shows an example in which an external resistor is added to a combination of a stabilized current source having a band gap reference type bias circuit and a stabilized current source having a diode stacked type bias circuit. However, the same effect can be obtained by adding an external resistor to the combination of a stabilized current source with a band gap reference type bias circuit and a stabilized current source with a V _BE multiplier type bias circuit. Can be.

FIG. 4 shows a fourth embodiment of the stabilized current source according to the present invention, which includes a bias circuit of a type that combines the output voltages of a band gap reference type bias circuit and a diode stacked type bias circuit. 2 shows a stabilized current source provided.

In FIG. 4, reference numeral 11 denotes a transistor;
Are resistors, and these constitute a current source 10. Three
Reference numerals 1 and 32 denote transistors, and reference numerals 33 to 35 denote resistors.
And 41 to 43 are transistors, 44 to 4
Reference numeral 7 denotes a resistor, which forms a band gap reference type bias circuit 40.

Further, reference numerals 61 and 62 denote resistors, which constitute a coupling circuit 60, and an output voltage of the coupling circuit 60 is supplied as a bias circuit of the current source 10. Reference numeral 50 denotes a load circuit that receives a supply of a bias current from the current source 10 (in the figure, simply referred to as a load).

The output voltage of the diode-stacked bias circuit is based on the base voltages of all the transistors in the integrated circuit.
Considering that the emitter-to-emitter voltages V _BE are almost equal, V ₂ = 2R ₃₅ V _BE / (R ₃₄ + R ₃₅ ). Therefore, this output voltage has a negative temperature coefficient.

On the other hand, considering that the base-emitter voltages of all the transistors in the integrated circuit are almost constant, the output voltage of the band gap reference type bias circuit is V ₃ = V _BE + R ₄₅ / R ₄₇ V _T ln N. Here, since it is easy to set the variation of the second term to be larger than the variation of the first term on the right side, the temperature coefficient of this output voltage can be made positive.

Then, if the impedance level of the coupling circuit is set sufficiently higher than the impedance level of the two bias circuits, and the base current of the transistor 11 is ignored (usually, the amplification factor β of the transistor is generally sufficient). Therefore, this assumption holds true.), The voltage obtained by combining the output voltages of the two bias circuits is V = (R ₆₂ V ₃ + R ₆₁ V ₂ ) / (R ₆₁ + R ₆₂ ), that is, the second bias The output voltage of the circuit is set to two resistors R
_Since the voltage is obtained by adding the inverse ratio of ₆₁ and _R62 , the temperature coefficient of the output voltage of the second bias circuit can be canceled.

Therefore, the temperature coefficient of the output current of the current source 10 can be suppressed. FIG. 4 shows an example in which the output voltages of the diode-stacking type bias circuit and the band gap reference type bias circuit are combined. However, the V _BE multiplier type bias circuit and the band gap reference type bias circuit are combined. The same effect can be obtained by combining the output voltages of the bias circuits.

FIG. 5 shows a first embodiment of the data receiving circuit of the present invention, in which the stabilized current source having the configuration shown in FIG. 1 is applied. In FIG. 5, 11 is a transistor, 12 is a resistor, and these constitute a current source 10, 11a is a transistor, 12a is a resistor, and these constitute a current source 10a. Then, the output currents of the current source 10 and the current source 10a are coupled to each other.

Reference numeral 21 denotes a transistor, and reference numerals 22 to 24 denote resistors. These constitute a V _BE multiplier type bias circuit 20, and its output voltage is supplied to the current source 10a. Reference numerals 41 to 43 denote transistors, and reference numerals 44 to 47 denote resistors. These constitute a band-gap reference type bias circuit 40, whose output voltage is supplied to the current source 10.

Then, 51 and 52 transistors, 53
And 54, resistors, which constitute a load circuit 50 receiving a bias current from the current source 10 and the current source 10a.

The V _BE multiplier type bias circuit 2
The temperature coefficient of the current of the current source 10a that receives the supply of the bias voltage from 0 is negative, and the temperature coefficient of the current of the current source 10 that receives the supply of the bias voltage from the band gap reference type bias circuit 40 is Since it is positive,
As already described in the description of the configuration of FIG. 1, it is possible to suppress the temperature coefficient of the current obtained by combining the currents of the two current sources.

Therefore, the voltage drop in the resistor 50 and the resistor 54 is hardly affected by the temperature fluctuation, so that the data receiving circuit having the configuration of FIG. 5 is a circuit stable against the temperature fluctuation.

FIG. 6 shows a data receiving circuit according to a second embodiment of the present invention, in which the stabilized current source having the configuration shown in FIG. 2 is applied. In FIG. 6, 11 is a transistor, 12 is a resistor, and these constitute a current source 10, 11a is a transistor, 12a is a resistor, and these constitute a current source 10a. Then, the output currents of the current source 10 and the current source 10a are coupled to each other.

Reference numerals 31 and 32 denote transistors, and reference numerals 33 to 35 denote resistors. These constitute a diode-stacked bias circuit 30 whose output voltage is supplied to the current source 10a. Reference numerals 41 to 43 denote transistors, and reference numerals 44 to 47 denote resistors.
A gap reference type bias circuit 40 is configured, and its output voltage is supplied to the current source 10.

Then, 51 and 52 transistors, 53
And 54, resistors, which constitute a load circuit 50 receiving a bias current from the current source 10 and the current source 10a.

The diode stack type bias circuit 3
The temperature coefficient of the current of the current source 10a that receives the supply of the bias voltage from 0 is negative, and the temperature coefficient of the current of the current source 10 that receives the supply of the bias voltage from the band gap reference type bias circuit 40 is Since it is easy to make it positive, it is possible to suppress the temperature coefficient of the current obtained by combining the currents of the two current sources, as already described in the description of the configuration of FIG.

Therefore, the voltage drop in the resistor 53 and the resistor 54 is hardly affected by the temperature fluctuation, and the data receiving circuit having the structure of FIG. 6 is a circuit stable against the temperature fluctuation.

FIG. 7 shows a third embodiment of the data receiving circuit according to the present invention, in which the stabilized current source having the configuration shown in FIG. 3 is applied. In FIG. 7, reference numeral 11 denotes a transistor, 12 denotes a resistor, and 13 denotes a resistor added externally so as to be connected in parallel to the resistor 12, and these constitute a current source 10, 11a is a transistor, 12a is a resistor, Reference numeral 13a denotes a resistor added externally so as to be connected in parallel with the resistor 12a, and these constitute a current source 10a. Then, the output currents of the current source 10 and the current source 10a are coupled to each other.

Reference numerals 31 and 32 denote transistors, and reference numerals 33 to 35 denote resistors. These constitute a diode-stacked bias circuit 30, and its output voltage is supplied to the current source 10a. Reference numerals 41 to 43 denote transistors, and reference numerals 44 to 47 denote resistors.
A gap reference type bias circuit 40 is configured, and its output voltage is supplied to the current source 10.

Then, 51 and 52 transistors, 53
And 54, resistors, which constitute a load circuit 50 receiving a bias current from the current source 10 and the current source 10a.

As described in detail in the description of the stabilized current source having the configuration shown in FIG. 3, by adding an external resistor to the emitter circuit of the transistor constituting the current source, the current source 1
Since it is possible to arbitrarily adjust 0 and the current of the current source 10a, it becomes possible to arbitrarily adjust the temperature coefficient of the current obtained by combining the currents of the current source 10 and the current source 10a.

Therefore, the temperature coefficients of the currents of the current source 10 and the current source 10a can be easily offset, and the resistance 5
3 and the voltage drop across the resistor 54 are less susceptible to temperature fluctuations. As a result, the configuration of FIG. 7 and the data receiving circuit are stable circuits that are not affected by temperature fluctuations.

In this embodiment, two external resistors are connected in parallel to the resistor 12 and the resistor 12a. However, the two external resistors are connected to the resistor 12 and the resistor 12a, respectively.
It is also possible to adopt a configuration in which a is connected in series to a.

FIG. 3 shows an example in which an external resistor is added to a combination of a stabilized current source having a band gap reference type bias circuit and a stabilized current source having a diode stacked type bias circuit. The same effect can be obtained by adding an external resistor to a combination of a stabilized current source having a band gap reference type bias circuit and a stabilized current source having a V _BE multiplier type bias circuit.

FIG. 8 shows a data receiving circuit according to a fourth embodiment of the present invention, in which the stabilized current source having the configuration shown in FIG. 4 is applied. In FIG. 8, 11 is a transistor, 12 is a resistor, and these constitute the current source 10.

Also, 31 and 32 are transistors, 33 to 35 are resistors, and these constitute a diode-stacked bias circuit 30. 41 to 43 are transistors, and 44 to 47 are resistors, and these are band-gap transistors. A reference type bias circuit 40 is configured.

Further, reference numerals 61 and 62 denote resistors, which constitute a coupling circuit 60, and the output voltage of the coupling circuit 60 is supplied as a bias circuit of the current source 10. The transistors 51 and 52 and the resistors 53 and 54 are resistors, and constitute a load circuit 50 that receives a bias current supplied from the current source 10.

The temperature coefficient of the output voltage of the diode-stacked bias circuit is negative. On the other hand, it is easy to make the temperature coefficient of the output voltage of the band gap reference type bias circuit positive.

Therefore, if the output voltages of the two bias circuits are coupled by the resistors 61 and 62 sufficiently higher than the impedance level of the bias circuit, it becomes possible to cancel the temperature coefficient of both output voltages.

Therefore, the temperature coefficient of the output current of the current source 10 can be suppressed, and the data receiving circuit having the configuration shown in FIG. 8 is a stable circuit which is hardly affected by temperature fluctuation. FIG. 8 shows an example in which the output voltages of the diode-stacking type bias circuit and the band gap reference type bias circuit are combined, but the V _BE multiplier type bias circuit and the band gap reference type bias circuit are combined. The same effect can be obtained by combining the output voltages of the bias circuits.

Although V _BE has been defined as the base-emitter voltage, it is generally the terminal voltage of a diode-connected transistor when a forward current flows through the transistor.

In the above description of the data receiving circuit, a current switch constituted by the transistor 51 and the transistor 52 and a load circuit constituted by a resistor connected to the transistor 51 and the collector of the transistor 52 will be exemplified. However, the form of the load circuit need not be limited to this. For example, if a laser diode is connected to one of the collectors of the transistors constituting the current switch, a stable data receiving circuit that performs electro-optical conversion can be formed. can do.

[0097]

According to the first aspect of the present invention, the output current of the stabilized current source having a positive temperature coefficient and the output current of the stabilized current source having a negative temperature coefficient are combined, so that the current of the combined stabilized current source is reduced. The temperature coefficient can be suppressed.

According to the second aspect of the present invention, the temperature coefficient of the combined voltage can be suppressed by coupling the stabilized voltage source having the positive temperature coefficient and the output voltage of the bias circuit having the negative temperature coefficient. The temperature coefficient of the current of the coupled stabilizing current source can be suppressed.

According to the third invention, since the temperature coefficient of the current of the stabilized current source obtained by the first invention or the second invention is small, the temperature coefficient of the output amplitude of the data receiving circuit can be suppressed. Therefore, a data receiving circuit that is stable against temperature fluctuations can be obtained.

Further, since there is no need to limit the manufacturing process of an element or an integrated circuit which can be used for the above-mentioned stabilized current source and data receiving circuit, the present invention is greatly reduced in size and cost of a communication device. Can contribute.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of a stabilized current source according to the present invention.

FIG. 2 shows a second embodiment of the stabilized current source according to the present invention.

FIG. 3 shows a third embodiment of the stabilized current source according to the present invention.

FIG. 4 is a fourth embodiment of the stabilized current source according to the present invention.

FIG. 5 is a first embodiment of a data receiving circuit of the present invention.

FIG. 6 shows a data receiving circuit according to a second embodiment of the present invention.

FIG. 7 shows a third embodiment of the data receiving circuit of the present invention.

FIG. 8 shows a data receiving circuit according to a fourth embodiment of the present invention.

FIG. 9 is a configuration example (part 1) of a conventional stabilized current source.

FIG. 10 shows a configuration example (part 2) of a conventional stabilized current source.

FIG. 11 is a configuration example (part 3) of a conventional stabilized current source.

FIG. 12 is a configuration example of a conventional data receiving circuit.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Current source 10a Current source 20V _BE multiplier type bias circuit 30 Diode stack type bias circuit 40 Band gap reference type bias circuit 50 Load circuit 60 Coupling circuit 11 Transistor 12 Resistance 13 External resistance 11a Transistor 12a Resistance 13a External resistance 21 Transistor 22, 23, 24 Resistance 31, 32 Transistor 33, 34, 35 Resistance 41, 42, 43 Transistor 44, 45, 46 Resistance 51, 52 Transistor 53, 54 Resistance 61, 62 Resistance

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5J090 AA03 AA12 AA43 AA44 AA59 CA02 CA04 CN02 CN04 FA08 FN01 FN06 FN09 HA02 HA25 HA43 HN20 HN21 KA02 KA06 KA09 KA10 KA12 KA47 KA53 MA08 MA19 MA21 SA13 TA01

Claims (8)

[Claims] 1. A current of a first stabilized current source which is stable with respect to power supply voltage fluctuation and has a positive temperature coefficient with respect to temperature fluctuation, and a temperature fluctuation which is stable with respect to power supply voltage fluctuation. Wherein a current of a second stabilized current source having a negative temperature coefficient is added to the stabilized current source. 2. The stabilized current source according to claim 1, wherein a stabilized current source having a band gap reference type bias circuit is applied as the first stabilized current source, and A stabilized current source including a V _BE multiplier type bias circuit as the stabilized current source. 3. The stabilized current source according to claim 1, wherein the stabilized current source having a positive temperature coefficient is a stabilized current source including a band gap reference type bias circuit. A stabilized current source comprising a stabilized current source having a diode-stacked bias circuit as the stabilized current source having a negative temperature coefficient. 4. The stabilized current source according to claim 2, wherein the addition ratio of the currents of the two current sources can be adjusted by a resistor connected to the outside. Regulated current source. 5. A voltage of a first bias circuit, which is stable with respect to power supply voltage fluctuation and has a positive temperature coefficient with respect to temperature fluctuation, and is stable with respect to power supply voltage fluctuation and with respect to temperature fluctuation. A voltage obtained by adding a voltage of a second bias circuit having a negative temperature coefficient at a specific ratio as a bias voltage. 6. The stabilized current source according to claim 5, wherein a band gap reference type bias circuit is applied as the first bias circuit, and a V _BE multiplier type bias circuit is used as the second bias circuit. A stabilized current source characterized by applying the bias circuit of (1). 7. The stabilized current source according to claim 5, wherein a band gap reference type bias circuit is applied as the first bias circuit, and a diode stacked type bias is used as the second bias circuit. A stabilized current source characterized by applying a circuit. 8. A data receiving circuit receiving a bias current from the stabilized current source according to claim 1.