JPH04322514A - Oscillation circuit - Google Patents

Abstract

PURPOSE:To obtain a triangle wave oscillation circuit whose oscillated waveform is subjected to optional DC, shift, whose circuit scale is not increased and whose output is connected to a next stage. CONSTITUTION:The 1st output terminal of a current control circuit 2 is connected to the noninverting terminal of a comparator 1 and to a reference voltage source 4 via a 1st resistor 3, and the 2nd output terminal of a current control circuit 2 and a capacitor 6 are connected to the inverting terminal of the comparator 1 to form the triangle wave oscillation circuit. A 1st transistor(TR) 12 whose base and collector are short-circuited is provided between the noninverting terminal of the comparator 1 and the 1st resistor 3. A 1st power supply circuit 14 is connected between the power supply and the noninverting terminal. The inverting terminal and the base of a 2nd TR 13 are connected, the collector is connected to the power supply and the emitter is connected to a 2nd power supply circuit 15. A 2nd resistor 16 is provided between the emitter of a 2nd TR 13 and the 2nd current source 15. The oscillating waveform is subjected to optical DC shift, the result is extracted and the oscillation circuit is connected to a next stage.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oscillation circuit that oscillates a triangular wave.

0002

2. Description of the Related Art FIG. 5 is a diagram showing the configuration of an example of a conventional triangular wave oscillating circuit. In the example shown in FIG. 5, when the output of comparator 1 becomes "H", current I1 flows through the non-inverting terminal of comparator 1, and when the output becomes "L", current I2 flows through the non-inverting terminal of current control circuit 2. Output 1 is connected, and reference voltage 4 is connected via resistor 3. On the other hand, current I3 flows to the inverting terminal when the output of comparator 1 becomes "H", and current I4 flows when the output becomes "L".
is connected to the output 2 of the current control circuit 2 through which the current flows, a capacitor 6 is connected, and an output terminal 7 is connected between the inverting terminal and the capacitor 6.

Next, the operation of the conventional circuit shown in FIG. 5 will be described below. In FIG. 5, the voltage vC at the output terminal 7 is considered to be 0 at the moment when the power is applied because the capacitor 6 is not charged. Therefore, the voltage vR of 19
Since the relationship between and vC is vR > vC, the output of comparator 1 becomes "H" level. At this time, the current I
1 flows, and the voltage vRH of 19 is: vRH=VREF +R1 I1 -------
−(1). Also, due to the current I3, the capacitor 6
is charged. Due to this charging, the potential of vC gradually rises, and when it exceeds the value of vRH, the output voltage of comparator 1 becomes "L" level. At this time, current I2 flows. Therefore, the voltage vRL of 19 is: vRL=VREF −R1 I2 −
-----(2). Also, the capacitor 6 has a current I
4, it enters a discharge state, and when vRL>vC, the output of the comparator becomes "H" and the same operation as above is repeated. In this way, by charging and discharging the capacitor 6, a triangular wave is oscillated between vRH and vRL, as shown in FIG. Also, capacitor C, resistors R1, I1, I2, I3
, I4, the threshold and oscillation frequency of the triangular wave can be determined. At this time, the oscillation frequency f is as follows.

0004

However, in the above-described conventional oscillation circuit, when a circuit is connected in which the current flowing into and out of the terminal 7 cannot be ignored, the oscillation waveform changes. Therefore, there was a problem that the terminal 7 could not be connected to the next stage. Therefore, as shown in FIG. 7, it is conceivable to output terminal 7 to terminal 8 using an emitter follower. However, with this method, the oscillation frequency does not change, but the voltage at terminal 7 is Vout1, the voltage at terminal 8 is Vout2, and the voltage between the base and emitter of transistor 9 is VBE9.
Then, Vout2=Vout1−VBE9
--------(4), and D
There was a problem that the C voltage shifted. Furthermore, as shown in FIG. 8, it is also conceivable to connect the terminal 7 to the next stage via the buffer 10. However, with this method, the oscillation frequency and voltage do not change, but since the buffer is configured,
There was a problem that the circuit scale became large.

[0005] The purpose of the present invention is to solve the above-mentioned problems,
The present invention aims to provide a triangular wave oscillation circuit which can arbitrarily DC shift the oscillation waveform and whose output can be connected to the next stage without increasing the circuit scale.

[0006]

[Means for Solving the Problems] The oscillation circuit of the present invention connects the first output terminal of the current control circuit to the non-inverting terminal of the comparator, connects the reference voltage via the first resistor, and connects the inverting terminal to the first output terminal of the current control circuit. is connected to the second output terminal of the current control circuit, and in a triangular wave oscillation circuit connected to a capacitor, a first transistor with a base-collector short circuit is provided between the non-inverting terminal of the comparator and the first resistor, and the power supply is connected to the second output terminal of the current control circuit. A first current source circuit is connected between the non-inverting terminals, the inverting terminal and the base of the second transistor are connected, the collector is connected to the power supply, the emitter is connected to the second current source circuit, and the second current source circuit is connected between the non-inverting terminals. This is characterized in that a second resistor is provided between the emitter of the transistor and the second current source circuit.

[0007]

[Operation] In the above configuration, the oscillation waveform can be arbitrarily DC shifted by the second resistor provided between the emitter of the second transistor and the second current source circuit, and the IC can be implemented using transistors with the same characteristics. It is possible to stabilize the oscillation frequency while making it easy to eliminate the influence from the next stage, and furthermore, since there is no need for large circuits such as buffers, the circuit scale can be reduced.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing the configuration of an embodiment of an oscillation circuit according to the present invention. In the embodiment shown in FIG. 1, a current source circuit 14 is connected between the power supply VCC and the non-inverting terminal of the comparator 1, and a base-collector shorted transistor 12 is connected between the non-inverting terminal and the resistor 3. The emitter of the transistor 12 is connected to the resistor 3 and to the output 1 of the current control circuit 2. Further, one end of the resistor 3 is connected to a reference voltage 4. Further, in the output 1 of the current control circuit 2, a current I6 flows when the output of the comparator 1 becomes "H", and a current I7 flows when the output becomes "L".

On the other hand, an output 2 of a current control circuit 2 is connected to an inverting terminal of the comparator 1, and a capacitor 6 is connected thereto. Further, a transistor 13 is provided, the base of the transistor 13 is connected to an inverting terminal, the collector is connected to VCC, and the emitter is connected to a current source circuit 15 via a resistor 16. Furthermore, terminals 17 and 18 are provided at both ends of the resistor 16. Note that the current I8 flows through the output 2 of the current control circuit 2 when the output of the comparator 1 becomes "H", and the current I9 flows when the output becomes "L".
flows.

Next, the operation of the embodiment of the present invention shown in FIG. 1 will be described. At the moment when the power is applied, a voltage of 21 vC
' is vC '=0 because capacitor 6 is not charged.
I think so. Therefore, since the relationship between the voltages vR' and vC' of 20 is vR'>vC', the output of the comparator 1 becomes "H" level. At this time, the current I6
flows. Therefore, the current flowing through the resistor R1 is the sum of the constant current I5 and the current I6 of the current source circuit, so it is 20
The voltage vRH' is vRH'=VREF +R1
(I5+I6) +VBE12
--------(5) It becomes. However, VBE12 is the voltage between the base and emitter of the transistor 12. At this time, the voltage v17 at the final point when charging the terminal 17
If the voltage between the base and emitter of transistor 13 is VBE13, then H is v17H = VREF
+R1 (I5+I6) +VBE12-VBE13
=VREF +R1 (I5+I6)
------
--(6) becomes. Further, the capacitor 6 is charged by the current I8. Due to this charging, the potential of vC gradually rises, and when it exceeds the value of vRH', the comparator 1
The output voltage of becomes "L" level. The voltage vRL' at 20 at this time is vRL'=VREF +R1(I
5-I7) +VBE12 (I5>I7)
-----(7) Since the capacitor 6 is in a discharge state due to the current I9, the voltage v17L at the final point when the terminal 17 is discharged is v17L = VREF
+R1 (I5-I7) +VBE12-VBE13
=VREF +R1 (I5-I7)
--------
(8) becomes.

Here, equations (1), (2), (6), (8
) from I1 = I5 + I6
−
-----(9) -I2 =I5 -I7

------(10) I5, I6
, I7, a voltage equivalent to that of the conventional circuit can be obtained. Furthermore, the terminal 17 can be connected to the next stage. Furthermore, when the terminal 18 is provided via the resistor 16, the voltage v18 of the terminal 18 is v18=v
17-R2 I10
−−−−−(11) So, v
17 can be level-shifted and output to terminal 18. The oscillation waveforms of vC' and v17 are shown in FIG.

As a modification of the present invention, FIG. 3 shows a circuit diagram in which the same circuit as that shown in FIG. 1 is constructed using PNP transistors 22 and 23. Further, FIG. 4 shows an example of an actual example of the comparator 1 and the current control circuit 2 of the circuit of FIG. When actually integrated into an IC, the present invention can be implemented by fabricating a circuit as shown in FIG.

[0013]

[Effects of the Invention] As explained above, in the triangular wave oscillation circuit of the present invention, an oscillation waveform obtained by arbitrarily DC shifting can be extracted from each output, and the output can be transferred to the next output without increasing the circuit scale. It has the effect of being able to connect to tiers. Further, since this circuit utilizes the pairing characteristics of each current source and each element, it is effective as an IC circuit.

[Brief explanation of drawings]

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

FIG. 2 is a diagram showing the state of triangular wave generation in the oscillation circuit of the present invention.

FIG. 3 is a diagram showing the configuration of another embodiment of the oscillation circuit of the present invention.

FIG. 4 is a diagram showing a specific example of the oscillation circuit of the present invention shown in FIG. 1;

FIG. 5 is a diagram showing the configuration of an embodiment of a conventional oscillation circuit.

FIG. 6 is a diagram showing a triangular wave generation state in a conventional oscillation circuit.

FIG. 7 is a diagram showing a portion of another example of a conventional oscillation circuit.

FIG. 8 is a diagram showing a portion of still another example of a conventional oscillation circuit.

[Explanation of symbols]

1 Comparator 2 Current control circuit 3 Resistor R1 4 Reference voltage 6 Capacitor 7, 8, 11, 17, 18 Output terminal 9,
12, 13 NPN transistor 10 Buffer circuit 14, 15 Current source circuit 16 Resistor R2 22, 23 PNP transistor

Claims (1)

[Claims] Claim 1: A first output terminal of a current control circuit is connected to the non-inverting terminal of the comparator, a reference voltage is connected via a first resistor, and a second output terminal of the current control circuit is connected to the inverting terminal. In a triangular wave oscillation circuit in which a capacitor is connected to , connect the inverting terminal and the base of the second transistor, connect the collector to the power supply, connect the emitter to the second current source circuit,
An oscillation circuit characterized in that a second resistor is provided between the emitter of the second transistor and the second current source circuit.