JPS62298216A - Charge/discharge oscillator to capacitor - Google Patents

Abstract

PURPOSE:To attain the excellent oscillation whose frequency is stable against temperature fluctuation by connecting a collector of an output transistor (TR) of a current mirror circuit comprising an NPN TR to a base of an NPN TR discharging the charge of a capacitor. CONSTITUTION:A base voltage of a TR 13 is higher than a base voltage of a TR 14, which is saturated, the electric charge of the capacitor 2 is discharged through a resistor 3, and the voltage reaches a low voltage VL of the TR 14, then TRs 25, 26 are conductive and the electric charge remained in the base of the TRs 4, 9 is discharged rapidly. Thus, the time of the TR 4 reaching the interrupting state from the saturation state is decreased. Since the collector of the TR 25 is connected to a base of the TR 4, the change in the resistance of a resistor 5 and the change in the saturated voltage of the TR 25 do not give effect on the time of transition of the TR 4 from the saturation state into the cut-off state.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention Field of Industrial Application The present invention relates to an oscillator that uses charging and discharging of a capacitor.

BACKGROUND OF THE INVENTION Conventionally, this type of oscillator has had a configuration as shown in FIG. In FIG. 2, 1 is a variable resistor that varies the charging current that charges the capacitor 2, 3 is a resistor that discharges the charge of the capacitor 2, 4 is a discharging transistor, 21, 22 .
23 is a current mirror circuit, 13g14 is a transistor forming a differential amplifier, 12 is a constant current circuit, 1
7゜18.19 is a resistor that determines the base voltage of the transistor 14, 9 is a transistor that changes the pace voltage of the transistor 14, 5 is a base resistor of the transistor 40, 8
is the base resistance of transistor 9. FIG. 3 shows the base voltage waveform of transistor 13.

The circuit operation will be described below with reference to these drawings. In the initial state, the base voltage of the transistor 14 is
Assuming that the voltage is higher than the base voltage of the transistor 13, the current obtained by the constant current source 12 flows through the current mirror circuit 2.
2 to the current mirror circuit 23, the transistor 1o becomes conductive. On the other hand, since no current flows through the current mirror circuit 21, the transistors 4 and 9
becomes blocked. At this time, a voltage is generated in the capacitor 2 that is charged through the variable resistor 1 from the power supply voltage Vcc. When this charging voltage reaches the base voltage of the other transistor 14 of the differential amplifier, that is, the high voltage value VH divided from the power supply voltage Vcc by resistors 17, 18 and 19, the transistor 13 becomes conductive. However, the transistor 14 is cut off. As the transistor 14 is cut off, the transistor 10 is also cut off, and the transistors 4 and 9, which are supplied with pace current by the current mirror circuit 21, are no longer saturated, and the collector voltages of these two transistors become almost zero, and the transistor 14 is turned off. The base voltage of is the low voltage value vL sized by resistors 17 and 18.
is set to

At the same time, the transistor 4 is saturated, so that the charge that has not been charged in the capacitor 2 is discharged through the discharging resistor 3 until the voltage reaches the low voltage value vL of the transistor 14. Oscillation continues by repeating the above operation.

Problems to be Solved by the Invention In such a conventional configuration, even if the base voltage of the transistor 13 reaches vL, charge remains at the base of the transistor 4, and the charge is discharged through the resistor 5. Therefore, since the transistor 4 remains conductive until the discharge ends, the charge in the capacitor 2 continues to be discharged, and charging starts at a voltage vL' lower than vL. This caused the inconvenience that the oscillation frequency was lower than the design value by υ.

The time during which the charge of the transistor 40 is released changes depending on the resistance value of the resistor 5 and the saturation voltage of the collector of the transistor 10. Therefore, temperature fluctuations cause the total resistance value and saturation voltage to change. A problem arose in that the oscillation frequency also changed. In particular, the higher the oscillation frequency, the greater the effect.

The present invention is intended to solve these problems, and aims to achieve good oscillation.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a method in which the collector of a transistor on the output side of a current mirror circuit composed of NPN transistors is connected to the base of an NPN transistor that discharges the charge of a capacitor. A capacitor charging/discharging oscillator is provided.

Effect: With this configuration, the time required for the transistor to discharge the charge in the capacitor from the saturated state to the cutoff state is shortened, and good oscillation is achieved.

Embodiment FIG. 1 is a circuit diagram of an oscillator according to an embodiment of the present invention. The difference from the conventional circuit shown in FIG. 2 is that in the conventional circuit, the collector of the transistor 1o on the output side of the current mirror circuit 23 is connected to the intersection of the base resistors 6 and 8, whereas in this circuit, the collector of the transistor 1o on the output side of the current mirror circuit 23 is The outputs of transistors 26 and 26 are connected to transistors 4 and 90, respectively. Note that the basic operation of the oscillator is the same as that of the conventional circuit, so a description thereof will be omitted. Therefore, the effects of transistors 25 and 26 will be described here.

First, the base voltage of transistor 13 is
When transistor 4 saturates above the base voltage of transistor 4 and the charge on capacitor 2 is discharged through resistor 3 and reaches the low voltage value vL of transistor 14, transistors 25 and 26 become conductive and transistors 4 and 9 Rapidly discharge any remaining charge at the base of the Therefore, the time required for the transistor 4 to change from the saturated state to the cutoff state is shortened.

Further, the collector of the transistor 25 is connected to the transistor 4.
Therefore, changes in the resistance value of the resistor 5 and changes in the saturation voltage of the transistor 25 do not affect the time it takes for the transistor 4 to change from the saturated state to the cut-off state.

Effects of the Invention As described above, according to the present invention, it is possible to obtain good excavation with a stable frequency even under fluctuations in temperature.

[Brief explanation of drawings]

Figure 1 shows an oscillator according to an embodiment of the present invention.
2 is a circuit diagram showing a conventional oscillator, and FIG. 3 is an oscillation waveform diagram. 1...Variable resistor, 2...Capacitor, 3
......Discharge resistor, 4...Discharge transistor, 5.8...Resistor, 9...Transistor, 12...Constant current Source, 13.14...
...Differential amplifier vs. transistor, 17°18.19
...Resistor, 20...Power terminal, 21゜22.23.2a...Current mirror circuit, 6
゜7.15.16...PNP 1-transistor, 10゜25.26.11...NPN transistor, vl! ...High level of oscillation waveform, vL,
vL'...Low level of oscillation waveform. Name of agent: Patent attorney Toshio Nakao and one other person E-=rsm [-2~-1 Cosoteria 3--Ichiseijoden' ni ni resisto°--I Transistor 5, δ, Me7. /B9---Delivery≦mff,7,IS・IG---/7A+/) Transistor 12-Constant/lL Kaigen 11 +4=-OTηDeincludeTmousevonotT)Run raster 20
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Claims (2)

[Claims] (1) A charge/discharge oscillator for a capacitor, characterized in that the collector of a transistor on the output side of a current mirror circuit constituted by an NPN transistor is connected to the base of an NPN transistor that discharges the charge of the capacitor. (2) A variable resistor whose one end is connected to the +B power supply and a capacitor whose one end is grounded are connected in series, and the first resistor is connected to the collector of the first NPN transistor whose emitter is grounded at the first connection point. the collector of a second NPN transistor whose emitter is grounded to the base of the first transistor and one end of the second resistor; a third NPN transistor whose base and emitter are grounded, whose collector is connected to the other end of a third resistor whose one end is connected to the other end of the second resistor, and whose emitter is grounded; The collector is connected to the base of a fourth NPN transistor connected to the base, the second, third, and fourth transistors constitute a first current mirror circuit, and the fifth and sixth NPN transistors Configure a dynamic amplifier, connect a constant current source between its emitter and ground,
Seventh and eighth PNP transistors and ninth and tenth PNP transistors
Second and third current mirror circuits each having an emitter connected to the +B power supply are formed of NP transistors, and the second
The collector of the eighth transistor on the drive side of the current mirror circuit is connected to the collector of the fifth transistor, and the collector of the seventh transistor on the output side is connected to the second resistor and the third transistor. The collector of the seventh transistor on the driving side of the third current mirror circuit is connected to the collector of the sixth transistor, and the collector of the seventh transistor on the output side of the seventh transistor is connected to the connection point with the resistor. The collector of the fifth transistor is connected to the collector of the fourth transistor, the base of the fifth transistor is connected to the first connection point, and the base of the sixth transistor is connected to the fourth transistor with one end connected to the +B power supply. The other end of the fifth resistor is connected to the connection point between the resistor and one end of the fifth resistor, and the emitter is connected to the other end of the sixth resistor whose one end is grounded, and whose base is connected to the third transistor. 2. The oscillator for charging and discharging a capacitor according to claim 1, wherein the oscillator is connected to the collector of the eleventh NPN transistor which is connected to the collector of the eleventh NPN transistor.