JPH0646683B2 - Pseudo waveform generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention uses a pseudo si
The present invention relates to a pseudo waveform generation circuit that obtains pseudo trigonometric function waveforms such as n waves and pseudo cos waves.

[Conventional technology]

Conventionally, in a pseudo waveform generating circuit that obtains pseudo waveforms such as pseudo sin wave and pseudo cos wave, as shown in FIG.
It voltages _V 1 from the connection point by the resistance ratio of the voltage divider circuit comprising a _reg resistors _2,4,6,8,10, V _2, V _3, and sets the _{V 4,} the voltages _V 1 ~V ₄ and the input voltage V _IN and each voltage V
Comparators 12, 14, 16, and ₁ installed for each _{1 to} V _4.
As shown in FIG. 5, a pseudo waveform representing a sin wave is obtained by making a comparison in FIG.

[Problems to be solved by the invention]

In such a pseudo waveform generating circuit, the precision of the pseudo waveform depends on the voltages V _{1 to} V ₄ , the precision of the resistance ratio of the resistors 2 to 10 affects the waveform precision, the number of resistors is large, and the resistance ratio setting is difficult. In addition, it has drawbacks such as being affected by temperature characteristics.

Therefore, the present invention reduces the number of resistors and eliminates the influence of temperature characteristics to improve the waveform accuracy.

[Means for solving problems]

In the pseudo waveform generating circuit of the present invention, as illustrated in FIG. 1, a buffer circuit (buffer amplifier 32) is installed, the output of the pseudo waveform generating circuit is received by the base of the transistor (34), and the output on the emitter side is the above-mentioned. A resistor (36) is connected between the output side of the buffer circuit and the emitter and ground, and the input triangular wave voltage is converted into a current having a level according to the level change, and a first current A first current generating means (voltage / current conversion circuit 30) for generating (I ₁ ) and a comparison circuit (46) are installed, and a reference voltage is set at the input part thereof to output the output of the comparison circuit. The base of the transistor (48) receives the output on the emitter side of the transistor (48) to the output side of the comparator circuit, and the resistor (50) is connected between the emitter and the ground. In the range where the triangular wave voltage is equal to or lower than the reference voltage, the triangular wave voltage is converted into a current having a level according to the level change, and in the range exceeding the reference voltage, a constant level current is obtained regardless of the level change of the triangular wave voltage. By converting, the second current (I) having an increasing region, a constant level region and a decreasing region corresponding to the triangular wave voltage is obtained.
₂ ) for generating the second current generating means (voltage / current conversion circuit 40) and the first and second currents obtained by the first and second current generating means are added to generate a pseudo sine wave. And a voltage conversion means (resistor 54) for converting into a half-wave waveform voltage.

[Action]

With this configuration, a triangular wave output is obtained by the first current I ₁ and a trapezoidal wave output is obtained by the second current I ₂ , so that a pseudo sin wave or a pseudo cos wave can be obtained by adding the two.

〔Example〕

FIG. 1 shows an embodiment of the pseudo waveform generating circuit of the present invention.

The input voltage V _IN applied to the input terminal 20 is a variable voltage that has a monotonous increase or decrease characteristic and that is based on a reference voltage V _refL that is different from the ground level and that generates the first and second currents. It is applied as a control input to each of the voltage / current conversion circuits 30 and 40 installed as means.

The voltage / current conversion circuit 30 includes a buffer amplifier 32, a transistor 34, and a resistor 36, and generates a _first current I ₁ having a linearly increasing or decreasing tendency according to the input voltage V _IN . The buffer amplifier 32 and the transistor 34 form an all-feedback amplifier, and when the resistance value of the resistor 36 is R ₁ , the first current I ₁ is And becomes a current that increases or decreases in proportion to the input voltage V _IN .

On the other hand, the voltage / current conversion circuit 40 sets a threshold voltage V _t as a constant reference voltage, and increases or decreases according to the input voltage V _IN like the first current I ₁ up to the threshold voltage V _t. However, the second current I ₂ becomes a constant value after the input voltage V _IN reaches the threshold voltage V _t.
To occur. That is, this voltage / current conversion circuit 40
Generates a current I ₂ according to the input voltage V _IN ,
Reference voltage V set by a voltage source (not shown)
_When the threshold voltage V _t set by dividing _refH and the reference voltage V _refL by the resistors 42 and 44 is exceeded, the current I ₂
Is provided with a comparison circuit 46 and a transistor 48 for keeping the constant value. The comparison circuit 46 uses the transistor 4
8 and the resistor 50 constitute an all-feedback amplifier, and the resistance value of the resistor 50 is R ₂ , the second current I ₂ is Next, the input voltage V _IN until the transition to the threshold voltage V _t, the current proportional to the input voltage V _IN.

The respective currents I ₁ and I ₂ are added on the line on the input side of the current mirror circuit 53 as the current conversion means, and the combined current I _T
(= I ₁ + I ₂ ) is added to the current mirror circuit 52. The current mirror circuit 52 has a resistor 5 as a voltage converting means connected to its output side by the current mirror effect.
A combined current I _{T is} passed through 4. Therefore, assuming that the resistance value of the resistor 54 is R ₃ , the output voltage V _OUT is V _OUT = R ₃ · _IT = R ₃ · (I ₁ + I ₂ ) ... (3), and the combined current I _T And an output voltage V _OUT determined by the product of the resistance value R ₃ is taken out from the output terminal 56.

With this configuration, when the currents I ₁ and I ₂ are considered separately, as shown in B of FIG. 2, by continuously increasing or decreasing the input voltage V _IN shown in the second A, A triangular wave voltage V _R1 is generated in the resistor 54 by the current I ₁ , and a trapezoidal wave voltage V _R2 is generated in the resistor 54 by the current I ₂ as shown in C of FIG.

Therefore, looking at the combined current I _T , each voltage V _R1 , V
_{Since R2} is generated by being combined with the resistor 54, the waveform output V _OUT
Is given by the combined value of the voltages V _R1 and V _R2 , as shown in D of FIG. 2, and a pseudo sin wave is obtained.

Then, by arbitrarily setting the respective values R _{1 to} R ₃ of the resistors 36, 50, 54, a desired pseudo sin wave can be obtained, the number of resistors is small, and the characteristics of the resistors 36, 50, 54 are It is possible to prevent irregularity, to obtain a highly accurate pseudo-waveform that has little variation and is not affected by temperature characteristics.

FIG. 3 shows a specific circuit configuration example of the pseudo waveform generating circuit shown in FIG.

The buffer amplifier 32 of the voltage / current conversion circuit 30 connects a transistor 322 for flowing an operating current and a resistor 323 to a differential pair composed of transistors 320 and 321, and also transistors 324, 3 as active loads.
25, 326 and resistors 327, 328 are connected to a current mirror circuit. An input voltage V _IN is applied from the input terminal 20 to the base of the transistor 320, and the base and emitter of the transistor 34 are connected between the collector and base of the transistor 321, thereby forming an all-feedback amplifier. A voltage V _IN is generated with respect to the resistor 36 connected to, and a current I ₁ is obtained through the transistor 34.

The comparison circuit 46 of the voltage / current conversion circuit 40 connects a transistor 462 and a resistor 463 for supplying an operating current to a differential pair composed of the transistors 460 and 461, and
Transistors 464, 465, 466 as active loads
And a current mirror circuit composed of resistors 467 and 468 are connected, the bases of the transistors 460 and 461 forming a differential pair are connected to level shift transistors 469 and 470, and the bases of the transistor 469 are connected to the resistors 42 and 44.
A voltage dividing circuit consisting of is installed, and the input voltage V _IN is applied to the base of the transistor 460 through the base and emitter of the transistor 471. And the transistor 47
The base and emitter of the transistor 48 are connected between the base of 0 and the collector of the transistor 461,
The comparator circuit 46 constitutes an all-feedback amplifier, generates a voltage V _IN at the resistor 5.0, and obtains a current I ₂ corresponding to an increase / decrease in the input voltage V _IN until the threshold voltage V _t is reached.

In addition, the current mirror circuit 52 includes transistors 520, 5
21 and resistors 522 and 523. Since the collectors of the transistors 34 and 48 are commonly connected, the currents I ₁ and I ₂ are combined, the combined current I _T flows to the transistor 521 side, and the currents I ₁ and I ₂ flow to the transistors 520 and 58 side due to the current mirror effect. Flow, causing a voltage drop across resistor 54.

Therefore, the combined current I _T flows through the resistor 54, and the waveform output V _OUT showing the pseudo sin wave shown in D of FIG. 2 is obtained from the output terminal 56.

Although the formation of the pseudo sin wave has been described in the embodiment, the pseudo cos wave can be similarly obtained in consideration of the phase relationship.

〔The invention's effect〕

According to the present invention, as compared with the case where a plurality of reference voltages are set and a pseudo waveform is formed, the number of resistors can be reduced, the circuit can be simplified, and the temperature characteristics with little variation are highly accurate. A pseudo waveform can be obtained.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a pseudo waveform generating circuit of the present invention, FIG. 2 is a diagram showing the operation of the pseudo waveform generating circuit shown in FIG. 1, and FIG. 3 is a pseudo waveform showing in FIG. FIG. 4 is a circuit diagram showing a concrete circuit configuration example of the waveform generating circuit, FIG. 4 is a circuit diagram showing a conventional pseudo waveform generating circuit, and FIG. 5 is a diagram showing the operation of the pseudo waveform generating circuit shown in FIG. is there. 30 ... Voltage / current conversion circuit (first current generation means) 32 ... Buffer amplifier (buffer circuit) 34 ... Transistor 36 ... Resistor 40 ... Voltage / current conversion circuit (second current generation means) 46 ...... Comparison circuit 48 ...... Transistor 50 ...... Resistance 54 ...... Resistance (voltage conversion means)

Claims (1)

[Claims] 1. A buffer circuit is installed, an output of the buffer circuit is received by a base of a transistor, and an output of an emitter side of the buffer circuit is fed back to an output side of the buffer circuit.
A resistor is connected between the emitter and the ground, the input triangular wave voltage is converted into a current having a level according to the level change, and a first current generating means for generating a first current, and a comparison circuit. And a reference voltage is set at its input, the output of the comparison circuit is received by the base of the transistor, the output of the emitter side is fed back to the output side of the comparison circuit, and the emitter and ground are connected. A resistor is connected between and receives the triangular wave voltage, converts the triangular wave voltage into a current having a level corresponding to the level change in the range of the reference voltage or less, and converts the triangular wave voltage of the triangular wave voltage in the range exceeding the reference voltage. A second current having an increasing region, a constant level region and a decreasing region is generated corresponding to the triangular wave voltage by converting into a constant level current regardless of the level change. Second current generating means, and voltage converting means for adding the first and second currents obtained by the first and second current generating means to convert into a pseudo-sine wave half-wave voltage. And a pseudo waveform generating circuit.