JPH01288104A - External synchronous type triangle wave generating circuit - Google Patents

Abstract

PURPOSE:To set the upper limit of a triangle wave output voltage to a prescribed value with respect to a power voltage by constituting the circuit by a differential amplifier circuit and two mirror circuits and connecting a capacitor between an output terminal and a ground terminal so as to save number of current sources and number of circuit components. CONSTITUTION:When a positive pulse signal is given to an input terminal 1, a TR Q16 of a differential amplifier circuit comprising TRs Q15, Q16 and a current source S9 is conductive and a current the same as that of the current source S9 flows to a capacitor C hy a current mirror, circuit comprising TRs Q24, Q26 to charge the capacitor C, TR Q15 of the differential amplifier circuit is conductive when the potential of the capacitor C reaches a value, and the charge in the capacitor C is discharged by a current equal to the current of the current source S9 by means of the current mirror comprising TRs Q21, Q23. Thus, a series of triangle wave voltage signals are outputted from an output terminal 4.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an externally synchronized triangular wave generating circuit that can set an upper limit on the triangular wave output voltage.

2. Description of the Related Art A conventional externally synchronized triangular wave generation circuit is shown in FIG. 2, and will be described with reference to FIG.

This circuit consists of a trigger synchronization signal input stage consisting of input terminal 1 and transistor Q1, transistors Q2, (h
and a flip-flop circuit consisting of Q4, resistors RI and R2, and constant current sources S1 and 32, a charging/discharging current source consisting of transistors Qs, Qe, and Q7, a capacitor C, and constant current sources S3 and 84, and transistors Qa and Q9. .

Q+o, Q ll+ Q10. Q13 and Q10
and a comparator consisting of constant current sources Ss, Ss, S7, Ss, and resistors R3 and R4.

Next, the operation of this circuit will be explained. In an initial state in which no trigger synchronization signal is input to the base of the transistor Ql, the capacitor C is already charged. In this state, when a trigger synchronization signal is applied to input terminal 1 so that transistor Q1 becomes conductive, the flip-flop circuit is set and the charging/discharging current source becomes capacitor C.
works to discharge the electric charge. A comparator compares a voltage (Vo) obtained by subtracting the base-emitter voltage of transistor QB from the potential of capacitor C with a reference voltage (VE) determined by current source S8 and resistor R4, and the voltage (Vo) is determined as the reference voltage (VE). When it becomes lower, the flip-flop circuit is reset and the capacitor C of the charging/discharging current source is charged. In this way, a triangular wave is output to the output terminal 2 by charging and discharging the capacitor C.

Problems to be Solved by the Invention A conventional externally synchronized triangular wave generation circuit is comprised of four blocks: a trigger synchronization signal input stage, a flip-flop circuit, a charging/discharging current source, and a comparator. Therefore, it has the disadvantage that it requires a large number of current sources and circuit elements. In addition, the lower limit of the triangular wave output voltage output to the output terminal 2 is determined by the reference voltage determined by the current limit S8 and the resistor R4 to be a constant voltage regardless of the input timing of the trigger synchronization signal. The upper limit differed depending on the input timing of the trigger synchronization signal.

The externally synchronized triangular wave generating circuit of the present invention reduces the number of current sources and circuit elements required by simplifying a complex circuit, and also keeps the upper limit of the triangular wave output voltage at a constant value with reference to the power supply voltage. The purpose of this is to make it possible to set the value to .

Means for Solving the Problems The externally synchronized triangular wave generating circuit of the present invention has an emitter grounded via a constant current source, a collector connected to a first resistor, and a base grounded via a second resistor. a first transistor whose emitter is connected to the constant current source, whose collector is connected to the third resistor, and whose base is grounded via the fourth resistor; a third transistor whose emitter is connected to the collector of the second transistor to the base of the first transistor via a fifth resistor; a third transistor whose collector is connected to the power supply and whose base is connected to the collector of the first transistor; a differential amplifier circuit configured with a fourth transistor whose emitter is connected to the base of the second transistor via a sixth resistor, whose collector is connected to the power supply, whose base is connected to the input terminal; a fifth transistor connected to the base of the second transistor; a sixth transistor whose collector is connected to the power supply, whose base is connected to the output terminal, and whose emitter is connected to the base of the first transistor;
a first current mirror circuit with one output terminal connected to the first resistor and the other output terminal connected to the base and collector of the seventh transistor;
a second current mirror circuit, the other output terminal of which is connected to the collector of the eighth transistor, and the bases of the seventh and eighth transistors are commonly connected; and between the output terminal and the ground terminal. and a capacitor connected to.

According to the externally synchronized triangular wave generating circuit of the present invention, the circuit configuration can be simplified, the number of circuit elements can be reduced, and the upper limit of the triangular wave output voltage can be set to a constant voltage.

Embodiment An embodiment of an externally synchronized triangular wave generating circuit according to the present invention will be described with reference to the circuit diagram shown in FIG.

This circuit consists of a transistor QCs whose emitter is grounded via a constant current source S9, whose collector is connected to a resistor R5, and whose base is grounded via a resistor R6; a transistor Q+s whose base is grounded via a resistor R8;
Collector is power supply terminal 3, base is transistor QCs
a transistor QI7 whose emitter is connected to the base of the transistor QCs via a resistor R9;
Collector is power supply terminal 3, base is transistor Q+s
A differential amplifier circuit is connected to the collector of the transistor QCs, the emitter of which is connected to the base of the transistor Q+e via the resistor RIO, and the collector of which is connected to the power supply terminal 3.
, the base is connected to input terminal 1, and the emitter is connected to transistor Q.
An emitter follower circuit consisting of a transistor QCs connected to the base of Cs, an emitter follower circuit consisting of a transistor Q20 whose collector is connected to the power supply terminal 3, whose base is connected to the output terminal 2, and whose emitter is connected to the base of the transistor QCs, and whose emitter is connected to the power supply terminal 3. The transistor Q21 has a collector connected to the collector and base of the transistor Q22 at the terminal 3, and a transistor Q23 whose emitter is connected to the power supply terminal 3 and whose base and collector are commonly connected to the resistor R5 and the base of the transistor Q2+. a transistor Q24 whose emitter is connected to the power supply terminal 3 and whose collector is connected to the collector of the transistor Q2S; whose emitter is connected to the power supply terminal 3 and whose base and collector are commonly connected to the resistor R7 and the base of the transistor Q24. A second current mirror circuit is provided with a second current mirror circuit consisting of a transistor Q2G connected to This is the configuration.

Next, the operation of this circuit will be explained. When a pulse signal with a positive voltage peak is applied to input terminal 1, the differential amplifier circuit consisting of transistors Q+s and QCs and current source S9 has transistor QCs conductive, and transistor Q16.
is fixed in the cut-off state, and since the transistor Q25 is cut-off, a current having the same value as the current of the current source S9 flows into the capacitor C by the current mirror circuit of the transistors Q24 and 026, and the capacitor C is charged.

Since the potential of the capacitor C is returned to the base of the transistor QCs of the differential amplifier circuit by the emitter follower of the transistor Q20, when the potential of the capacitor C reaches a certain value, the transistor QCs of the differential amplifier circuit becomes conductive and the transistor Q+e is cut off. is fixed in the current state. Then, a current mirror circuit consisting of transistors Q21 and Q23 turns on transistor Q25, and current source S9
The charge in capacitor C is discharged with a current equal to the current value of . In this way, when a series of trigger pulses having a certain positive voltage value is applied to the input terminal 1, the above operation is repeated and a series of triangular wave voltage signals is outputted to the output terminal 4. In addition, in the case of this circuit, the upper limit voltage of the triangular wave is
It is determined by the ratio of the two emitter-base voltages (VBE) and resistors R and R8.

Effects of the Invention According to the externally synchronized triangular wave generation circuit of the present invention, a triangular wave can be generated with a simple circuit configuration with fewer circuit elements, and a triangular wave generated in synchronization with a pulse signal having a positive voltage value can be generated. The upper limit of the signal voltage can be set at a certain value based on the power supply voltage. As a result, manufacturing costs are reduced and circuit design becomes easier.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an externally synchronized triangular wave generation circuit of the present invention.
FIG. 2 is a circuit diagram of a conventional externally synchronized triangular wave generating circuit. 1...Input terminal, 2...Output terminal, 3
・・・・・・Power terminal, QCs, Q 1B+ Q1
7. Q10, QCs, Q20゜Q211 Q
221 Q231 Q241 Q=s+ Q26°゛゛°°Transistor, Rs, Rs, R7, Ra, R
s, R+o-...Resistor, S9... Constant current source, C... Capacitor.

Claims (1)

[Claims] The emitter is grounded through a constant current source, and the collector is connected to the first
a first transistor whose base is grounded through a second resistor, whose emitter is connected to the constant current source, whose collector is connected to a third resistor, and whose base is connected to the ground through a fourth resistor; a third transistor whose collector is connected to the power supply, whose base is connected to the collector of the second transistor, and whose emitter is connected to the base of the first transistor through a fifth resistor; and a fourth transistor whose collector is connected to the power supply, whose base is connected to the collector of the first transistor, and whose emitter is connected to the base of the second transistor via a sixth resistor. a fifth transistor having a collector connected to the power supply, a base connected to the input terminal, and an emitter connected to the base of the second transistor; a collector connected to the power supply, a base connected to the output terminal, and an emitter connected to the second transistor; a sixth transistor connected to the base of the first transistor; a first current mirror circuit having one output terminal connected to the first resistor and the other output terminal connected to the base and collector of the seventh transistor; and a second current mirror in which one output terminal is connected to the third resistor, the other output terminal is connected to the collector of the eighth transistor, and the bases of the seventh and eighth transistors are connected in common. 1. An externally synchronized triangular wave generation circuit, comprising: a circuit; and a capacitor connected between the output terminal and a ground terminal.