JP2607310Y2 - Double wave detection circuit - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a detection circuit.
The present invention relates to a double-wave detection circuit that detects both positive and negative AC waves.

[0002]

2. Description of the Related Art FIG. 2 is a circuit diagram showing the configuration of a conventional example of a dual wave detection circuit.

In the circuit shown in FIG. 2, a capacitor C2
1, C22, C23, resistors R21, R22, R23, R
25, a coil L21 and a transistor Q21 constitute an input circuit, and diodes D21, D22, D2
3. A detection circuit is constituted by the resistors R24, R26, R27, R28 and the transistors Q22, Q23, Q24, Q25.

The structure of an input circuit will be described. The emitter of a transistor Q21 is a resistor R21 and a capacitor C21.
21 and an input terminal T21.
22 and connected to a -15V power supply. Transistor Q
The base of 21 is grounded via a resistor R23. The collector of the transistor Q21 is connected to a +15 V power supply via a coil L21 and a resistor R25.
To the emitters of the transistors Q21 and Q22. The midpoint between the coil L21 and the resistor R25 is grounded via a capacitor C22.

On the other hand, in the detection circuit, the emitters of the transistors Q23 and Q24 are connected to a + 15V power supply via resistors R26 and R27, respectively. The bases of the transistors Q23 and Q24 and the collector of the transistor Q23 are connected to the collector of the transistor Q22, and the collector of the transistor Q24 is connected to the output terminal T22. The emitters of the transistors Q22 and Q25 are connected to a capacitor C23.
It is connected to the. The base of the transistor Q22 is grounded via a capacitor C22, and the base of the transistor Q25 is grounded via a resistor R24. Three diodes D21, D23, D22 are provided in the forward direction between the base of the transistor Q22 and the base of the transistor Q25. The collector of the transistor Q25 is connected to the output terminal T22, and the output terminal T22 is grounded via the resistor R28.

When an AC signal is input to the input terminal T21 of the dual wave detection circuit, a waveform as shown in FIG. 3A in which the AC signal is amplified appears at the emitters of the transistors Q22 and Q25.

A transistor Q22 constituting a detection circuit stage
When an AC signal is input to each emitter of transistor Q25, transistor Q25 operates at the time of positive input, and transistor Q22 operates at the time of negative input. In response to each of these operations, a current mirror circuit constituted by transistor Q23 and transistor Q24 and operating as an output stage operates.
A detection waveform of both waves of the input AC signal as shown in (b) appears.

In the above-described dual-wave detection circuit, it is necessary to form transistors Q23 and Q24 constituting the current mirror circuit so that the same collector current flows by using transistors having the same characteristics.
However, the collector voltage of each transistor is different, and the collector loss and the amount of heat generated are different. As a result, a temperature difference occurs between the transistors and the characteristics thereof are also different, so that the collector current values flowing through the respective transistors also differ.

For example, the resistor R26 and the resistor R27
When a transistor having a resistance of 00Ω is used, a collector current of 5 mA flows through each transistor, and 1 V (P
When the waveform of -P) appears, if the forward voltage drop is 0.6 V, the collector voltage of the transistor Q23 becomes 13.9 V. On the other hand, since the collector voltage of transistor Q24 is set to about 1 V, each of transistors Q23 and Q24
Are about 3 mW and 68 mW, respectively, and a large difference occurs in the calorific value. For this reason, there is a difference in the time required for each transistor to reach the thermal equilibrium state, during which time the characteristics of each transistor (mainly VEB
Characteristic), and the output voltage becomes unstable.

Conventionally, in order to reduce the rate of change in the characteristics of each transistor due to the difference in the amount of heat as described above, a transistor having a large heat capacity is used as a transistor constituting a current mirror circuit, and the characteristics are rapidly increased. Was preventing it from changing.

[0011]

The conventional dual-wave detection circuit described above uses transistors having a heat capacity larger than necessary in the current mirror circuit in order to reduce the rate of change in the characteristics of each transistor. However, there is a problem that the selection range becomes small, the degree of freedom of design is low, and the cost is high.

The present invention has been made in view of the above-mentioned problems of the prior art, and has the same heat generation amount in the transistors constituting the current mirror circuit, and has high design flexibility. It is another object of the present invention to realize a dual-wave detection circuit capable of reducing cost.

[0013]

A dual wave detection circuit according to the present invention is a dual wave detection circuit in which a current mirror circuit is used in an output stage of a detection signal, wherein each collector of two transistors constituting the current mirror circuit is provided. A voltage shift element for equalizing the voltage is provided between a collector of at least one transistor and an output terminal.

[0014]

With the provision of the voltage shift element, the collector voltages of the two transistors constituting the current mirror circuit are made equal, so that the collector loss and the amount of heat generated in each transistor become equal. Therefore, the time required for each transistor to reach the thermal equilibrium state and the state of change in the characteristics during that time are the same, and the output voltage is always stable.

[0015]

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing the configuration of an embodiment of the present invention.

In FIG. 1, resistors R11 to R18, capacitors C11 to C13, diodes D11 to D13, a coil L
11, the configuration and operation of the input terminal T11, the output terminal T12 and the transistors Q11 to Q15 are the same as those of the resistors R21 to R28 and the capacitors C21 to C21 in the conventional example shown in FIG.
C23, diodes D21 to D23, coil L21, input terminal T21, output terminal T22, and transistor Q2
1 to Q25, the description is omitted.

In this embodiment, the transistor Q14
A Zener diode ZD11 which is a voltage shift element is provided between the collector of the first and the output terminals T12.

The Zener diode ZD11 has a Zener voltage VD of $ 12V. As in the conventional example shown in FIG. 2, when the resistors R16 and R17 each have a resistance of 100Ω, a collector current of 5 mA flows through each transistor, and a waveform of 1 V (PP) appears at the output terminal T12. Assuming that the forward voltage drop is 0.6V, the collector voltage of transistor Q13 is 13.9V. on the other hand,
The collector voltage of the transistor Q14 is the Zener voltage VD
Is applied, the voltage is set to about ≒ 13 V. Therefore, the collector loss of each of the transistors Q23 and Q24 is about 3 mW, and the heat generation amounts are substantially equal.

In the present embodiment having the above-described configuration, the amount of heat generated in the transistors Q13 and Q14 forming the current mirror circuit is substantially equal, so that the time required for each transistor to reach a thermal equilibrium state is obtained. , And the characteristics of the respective transistors during this period were substantially equal, so that the fluctuation of the output voltage could be suppressed.

In the present embodiment, the Zener voltage VD of the Zener diode ZD11 has been described as ≒ 12 V. However, this value may be determined by the output voltage value, the values of the resistors R16 and R17, and the current value. May be selected so that the collector voltages of the transistors constituting the transistors are substantially equal.

Although the description has been made assuming that a Zener diode is provided between the collector of one transistor and the output terminal as the voltage shift element, a transistor or the like may be used as the voltage shift element. It is not limited. Furthermore, elements having different shift voltages may be provided for each transistor, and the collector voltage may be adjusted with high accuracy.

[0023]

[Effects of the Invention] Since the present invention is configured as described above, the following effects can be obtained.

Since it is not necessary to use a transistor having a larger heat capacity than necessary as a transistor constituting the current mirror circuit, the degree of freedom in design can be increased and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a configuration of a conventional example.

FIGS. 3A and 3B are waveform diagrams showing the operation of the conventional example shown in FIG.

[Explanation of symbols]

 C11-C13 Capacitor R11-R18 Resistance D11-D13 Diode Q11-Q15 Transistor L11 Coil T11 Input terminal T12 Output terminal ZD11 Zener diode

 ──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-53-72444 (JP, A) JP-A-57-62779 (JP, A) JP-A-61-198065 (JP, A) JP-A-61-197965 241668 (JP, A) JP-A-63-80604 (JP, A) JP-A-63-7014 (JP, A)

Claims (1)

(57) [Scope of request for utility model registration] 1. A dual-wave detection circuit using a current mirror circuit at an output stage of a detection signal, wherein at least a voltage shift element for equalizing the collector voltages of two transistors constituting the current mirror circuit is provided. A dual-wave detection circuit provided between a collector of one transistor and an output terminal.