JPH0620117Y2 - Temperature detection circuit - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a temperature detection circuit for detecting a temperature using a pair diode, and has been improved so that the temperature can be accurately measured even when the temperature changes drastically. The present invention relates to a temperature detection circuit.

<Prior Art> FIG. 6 is a block diagram showing an outline of the configuration of a conventional temperature detection circuit.

A constant current source CC ₁ is connected to a + V power source at _one end, and the other end is connected to the collector of a transistor Q _{1 which} functions as a diode by connecting a base and a collector. The emitter of this transistor Q ₁ has a common potential point CO
It is connected to M.

In the above configuration, currents of different magnitudes, for example, current I and current N · I (N> 1), flow from the constant current source CC ₁ to the transistor Q ₁ and the voltage V _BE1 generated between the base and the emitter thereof. When the difference ΔV _BE between V _BE2 and V _BE2 is taken, ΔV _BE = V _BE1 −V _BE2 = kT · ln (N) / q (1) Where k is Boltzmann's constant, T is absolute temperature, q
Is the unit charge.

Therefore, since ΔV _BE is directly proportional to the absolute temperature T, the absolute temperature T can be known by contacting the portion of the transistor Q ₁ to be measured and measuring ΔV _BE .

<Problems to be solved by the present invention> However, in the conventional temperature detection circuit as described above,
Since the configuration is such that the constant current value is changed to measure ΔV _BE , the temperature cannot be accurately measured due to the influence of the temperature change in the external environment. In particular, there is a problem that an error that occurs occurs in a measurement target that undergoes a rapid temperature change.

<Means for Solving the Problems> In order to solve the above problems, the present invention repeats a constant current with a constant duty in which the peak value of the positive current and the peak value of the negative current are different from the reference value. A constant current source for output and a pair of pair diodes connected in series to the constant current source with opposite polarities and the voltage across which changes depending on the measurement temperature are provided, and the voltage across the pair diode is used to The temperature signal corresponding to the measured temperature is output.

<Operation> By applying constant currents having different peak values of positive and negative to paired diodes with good matching characteristics, which are connected in opposite polarities and are in contact with the temperature measurement point, voltage generated across these paired diodes is used. Use as a temperature signal. It is not affected by the surrounding environment, and it can accurately measure temperatures accompanied by sudden temperature changes.

<Embodiment> An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a circuit diagram showing the configuration of an embodiment of the present invention.

CC ₂ is a constant current source and is composed of transistors Q ₂ , Q ₃ , resistors R ₁ , R ₂ , a capacitor C ₁ , and the like.

The collector of the transistor Q ₂ is connected to the + V power supply,
Its emitter is connected to a transistor Q ₃ via resistors R ₁ and R _2.
Connected to the emitter. The collector of the transistor Q ₃ is connected to a power supply of -V.

In addition, at the connection point G of the bases of the transistors Q ₂ and Q ₃ , a signal pulse SP having a rectangular wave shape with a duty of 50% is supplied from the signal source.
Is being applied. Further, a capacitor C ₁ is connected to the connection point between the resistors R ₁ and R _2, and a signal pulse SP is output to the output terminal T _1.
An output current corresponding to is obtained.

In this case, the resistor R ₁ is selected to have a value N times that of the resistor R ₂ , that is, R ₁ = NR ₂ , so the peak value of the current I ₁ flowing out from the output end T is the same as that of the inflowing current I ₂ . It becomes 1 / N with respect to the peak value. Its duty is 50%.

The currents I ₁ and I ₂ are paired diodes D _p in which diodes D ₁ and D ₂ are connected in opposite polarities (detailed configuration will be described later).
Through the common potential point COM. These diodes D ₁ and D ₂ can be configured as diodes, for example, by connecting the base and collector of the transistor.

The voltage V _be generated across the pair diode D _p is applied to the smoothing circuit FL composed of the resistor R ₃ and the capacitor C ₂ , and the output voltage V _o is obtained across the capacitor C ₂ .

Next, the operation of the temperature detecting circuit configured as described above will be described with reference to FIG.

In the constant current source CC _2, the current I ₁ is passed through the diode D ₁ and the current I ₂ is passed through the diode D ₂ in the opposite direction to the current I _1. Therefore, V _be1 is across the diode D ₁ and the diode D ₂ is across the diode D _{1. 2}
V _be2 is alternately generated at both ends of the line as shown in FIG. 2 (A).

Therefore, these voltages V _be1 are applied across the capacitor C _2.
The output voltage V _o is obtained as V _o = (V _be1 −V _be2 ) / 2 = kT · ln (N) / q (2) as the difference voltage between V _be2 and V _be2 (FIG. 2 (B)).

Therefore, the output voltage V _o proportional to the absolute temperature T is obtained across the capacitor C ₂ .

In this case, when the diodes D ₁ and D ₂ are matched and V _{1 is} │I ₁ │ = │I ₂ │, V
It is necessary to make _be1 −V _be2 0,
The configuration for performing such matching will be further described with reference to FIGS.

FIG. 3A is a plan view of a silicon substrate forming a pair diode, FIG. 3B is a sectional view taken along line BB in FIG.
Is an electric circuit diagram.

1 denotes a silicon substrate, 3 a collector, 4 a base, 5 is the emitter, form a four transistor T _r 1 to T _r 4 close to each other on the silicon substrate 1.
In each of the transistors _Tr 1 to _Tr 4, 31 is a collector electrode coupled to the collector 3, 41 is a base electrode coupled to the base 4, and 51 is an emitter electrode coupled to the emitter 5. The collector electrode 31 and the base electrode 41 are connected to each other, and each of the transistors _Tr 1 to _Tr 4 operates as a diode.

The transistor T _r 1 and T _r 2 Metropolitan adjacent alongside one another, the collector electrode of the transistor T _r 1, the base electrodes 31 and 41, the transistor T _r 2 of the emitter electrode 51
And the emitter electrode 5 of the transistor T _r 1
1 is connected to the collector electrode and base electrodes 31 and 41 of the transistor T _r 2.

Similarly, in the transistor T _r 3 and T _r 4 adjacent alongside one another, the collector electrode of the transistor T _r 3, a base electrode 31, 41 is connected to the emitter electrode 51 of the transistor T _r 4, also the transistor T _r 3 The emitter electrode 51 is connected to the collector electrode and the base electrodes 31 and 41 of the transistor T _r 4.

71 and 72 are terminals connected to an external circuit (not shown),
61 is a collector electrode of the transistor T _r 1, base electrodes 31 and 41, and a miter electrode 51 of the transistor T _r 2.
A lead wire for connecting the terminals 71, 62 is an emitter electrode 51 and collector electrode of the transistor T _r 4 of the transistor T _r 3, a base electrode 31, 41 and re-de line connecting the terminals 71, 63 transistor T A lead wire connecting the emitter electrode 51 of _r 1 and the collector electrode of the transistor T _r 2, the base electrodes 31, 41 and the terminal 72, 64 is the collector electrode of the transistor T _r 3, the base electrode 31,
41 is a lead wire connecting the emitter electrode 51 of the transistor T _r 1 and the terminal 72.

The equivalent circuit seen from the terminals 71 and 72 of the circuit thus configured is as shown in FIG. 4 (A). That is, the transistors T _r 1 and T _r which are diagonally arranged on the substrate
4 are connected in parallel in the direction from the terminal 71 to the terminal 72, and the transistors T _r 2 and T _r 3 which are also arranged on the diagonal line are connected in parallel in the direction from the terminal 72 to the terminal 71. Will be connected.

In FIG. 4 (A), R _{61 to} R ₆₄ represent the resistance value of each lead wire. The equivalent circuit of FIG. 4 (A) is a diode-connected transistor T _r 1, T _r 4 and T.
_{If each of r} 2 and T _r 3 is represented by one diode, it can be further simplified as shown in FIG. 4 (B).

Here, the resistances r ₁ and r ₂ connected in series to the diodes D ₁ and D ₂ can be expressed by the following equations (3) and (4).

r ₁ = (R ₆₁ + R ₆₂ ) / 2 (3) r ₂ = (R ₆₃ + R ₆₄ ) / 2 (4) Lead wire 61 and lead wire 62, and lead wire 63 and lead wire 64 are all long. Can be formed to have the same width, and R ₆₁ = R ₆₂ and R ₆₃ = R ₆₄ can be formed. Even if these relationships are not satisfied, it is clear from the equations (3) and (4). As described above, the sum (r ₁ + r ₂ ) of the resistors connected in series to the diode can be accurately matched on the D ₁ side and the D ₂ side.

Further, the forward voltage delta ₁ of diodes D _1, D _{2, Δ 2} is if the forward voltage of the transistor T _r 1 to T _r 4 that is connected to the respective diodes with _{e 1 ~e 4 (5),} ( It can be expressed by the equation 6).

_{Δ 1 = (e 1 + e} 4) / 2 ... (5) Δ 2 = (e 2 + e 3) / 2 ... (6) e 1 ~e 4 is each transistor T _r 1 to T _r 4 under the same conditions By making it, it is possible to make e ₁ = e ₂ = e ₃ = e ₄ . Further, when there is a temperature gradient with respect to the substrate 10 as shown by the arrow a in FIG. 5, e ₁ = e ₂ , e ₃
= E ₄ is maintained, and when a temperature gradient as shown by the arrow b exists, e ₁ = e ₃ and e ₂ = e ₄ are maintained, and in each case, (5), ( As is clear from the equation (6), the relationship of Δ ₁ = Δ ₂ can be maintained without being affected by the temperature gradient.

In the above description, a diode-connected transistor is formed on the silicon substrate 1, but a diode may be directly formed instead of this transistor.

In the embodiment shown in FIG. 1, the constant current duty is 50.
However, the duty is not limited to this and may be N: 1. Further, the duty may be fed back so that the output becomes zero and the duty may be used as the temperature output signal.

<Effect of Device> As described above in detail with the embodiments, according to the present invention, positive and negative peak values are applied to paired diodes which are in contact with the temperature measurement point and have opposite polarities and which have good matching characteristics. Different temperature constant currents are applied and the voltage generated across these pair diodes is used as the temperature signal, so it is not affected by the surrounding environment and the temperature accompanied by a sudden temperature change can be measured accurately. .

[Brief description of drawings]

FIG. 1 is a circuit diagram showing the configuration of one embodiment of the present invention, FIG. 2 is a waveform diagram showing the waveform of each part shown in FIG. 1, and FIG. 3 is a pair diode of the pair diode shown in FIG. FIG. 4 is a configuration diagram showing the configuration, FIG. 4 is a circuit diagram showing an equivalent circuit of the pair diode shown in FIG. 3, FIG. 5 is an explanatory diagram explaining the effect of the pair diode shown in FIG. 3, and FIG. It is a circuit diagram which shows the structure of a temperature detection circuit. CC ₁ , CC ₂ ... constant current source, D _p ... pair diode, FL
... Smoothing circuit, SP ... Signal pulse, 1 ... Silicon substrate, 3
... collector, 4 ... base, 5 ... emitter, 31 ... collector electrode, 41 ... base electrode, 51 ... emitter electrode, 61
... 63 ... Lead wires, 71, 72 ... Terminals.

Claims (1)

[Scope of utility model registration request] 1. A constant current source that repeatedly outputs a constant current having a positive current peak value and a negative current peak value different from a reference value with a constant duty, and a constant current source having serially opposite polarities. And a pair of diodes whose voltage across both ends is changed according to the measured temperature, and a voltage signal across the pair of diodes is used to output a temperature signal corresponding to the measured temperature. Temperature detection circuit.