JPH0512757B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a sine wave generator that can input a triangular wave and obtain an output waveform that is extremely close to a sine wave.

[Conventional technology]

As is well known, sine wave signals in electronic equipment are
It is obtained by an oscillation circuit that generates a reference frequency signal and a sine wave generator that uses this reference signal as input to shape the waveform.

A polygonal line approximation circuit is most commonly used as such a waveform shaping circuit, but the biggest drawback of such a circuit device is the generation of differential noise.

Therefore, a circuit device shown in FIG. 6 is known as an example of a sine wave generator that is free from such concerns about differential noise generation.

That is, in a circuit device consisting of four-input multipliers M ₁ and M ₂ that input the reference frequency signal V, V ₀ =1.5715*V−0.004317*V ³ /1+0.001398*V.
Under the circuit transfer function denoted by ² , the sine wave output V ₀
appears.

[Problem to be solved by the invention]

By the way, in the conventionally known device with the above circuit configuration, firstly, the arithmetic elements used are special and the circuit configuration is relatively complicated, so the generator itself is expensive and the functionality is poor. As can be understood from the transfer function equation, the transfer function is a form obtained by dividing a cubic equation (numerator) by a quadratic equation (denominator), and does not include a division term (denominator) that is very disadvantageous in terms of signal processing. I'm here.

SUMMARY OF THE INVENTION Therefore, the present invention aims to develop a sine wave generator of this type that has a relatively simple circuit configuration to reduce costs, and is functional and convenient to use.

[Means to solve the problem]

In order to achieve such an objective, the present invention provides a triangular wave input to a first multiplier under the squarer connection,
The square wave output (signal only in the positive direction) from the multiplier is shifted to the negative side by a DC bias and applied to the Y input of the second multiplier, while the X input of the second multiplier is We propose a sine wave generator configured to receive a triangular wave input and obtain a cubic wave output approximating a sine wave.

Furthermore, an adder may be added to the configuration of this sine wave generator so that the cube wave output from the second multiplier and the triangular wave input are processed by the adder.

The triangular wave input is applied to the X input of the second multiplier via a third multiplier of the same type, which is effective as delay compensation means.

[Effect]

In the solution consisting of the above configuration,
When a triangular wave is input as the reference frequency signal, the approximation formula for the transfer function of this circuit is V ₀ ≒ - (X ³ - 3X) where V ₀ = sine wave output, X = triangular wave input, where The cubic wave output of is obtained as a sine wave.

Furthermore, according to the configuration of the added adder, under the adjustment of the shift voltage, the adder inputs the triangular wave input and the triangular wave input.
By adding or subtracting the multiplier output,
Finally, it is possible to obtain a transfer function of V ₀ =−(X ³ −3X).

The third multiplier inserted into the signal path to the X input of the second multiplier is not used as a functional arithmetic element here, but simply functions as a signal high-frequency propagation delay compensation path. .

This makes it possible to align the delay times of the X and Y input signals reaching the second multiplier, especially when the third multiplier is of the same type as the first multiplier.

〔Example〕

Next, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a circuit configuration diagram showing an embodiment of the present invention, in which a triangular wave input V as a reference frequency signal is
is connected to the wired X, Y inputs of multiplier A, while also connected to the X input of a second multiplier B.

The output of the multiplier A is connected to a DC bias section (V shift) connected in series with a constant current source, and the shifted output is transferred to the Y of the other multiplier B.
The circuit is connected to give it to the input. others,
V ₀ indicates the output of multiplier B.

Therefore, when a reference triangular wave with a peak of 1 V is input as the triangular wave input V of the embodiment circuit having such a configuration, the multiplier A receives 2
It functions as a multiplier, and a square wave (parabolic wave, see the waveform diagram shown in the main part of the circuit in the same figure) with an amplitude of 1V peak appears at its output.

This waveform output is the DC bias section (V shift)
Then, it is shifted to -3V and input to the Y input of multiplier B. At the same time, a triangular wave is input to the X input of multiplier B.
Since V is input, a cube waveform is generated at the output V ₀ .

This cube waveform closely approximates a sine wave, and by precisely adjusting V shift, a distortion rate of 0.001% or less can be achieved at a shift voltage of 3.0464808V.
The transfer function of this circuit is as shown in the following equation.

V ₀ =-(V ³ -V shift *V) The above circuit is constructed with the following modified transfer function.

V ₀ = -V (V ² -V shift) Letting this V be X, V at the lowest distortion rate point
shift becomes as follows.

2∫〓 ^/2 ₀ sinX dX− ^{∫ 1} ₀

FIG. 5 is a diagram showing the operating characteristics of this embodiment, and the solid line in the diagram indicates the most preferable operating state.

Although the distortion rate becomes a little high, the following equation can be used to simplify the calculation.

V ₀ ≒−(X ³ −3X) FIGS. 2 and 3 are circuit configuration diagrams showing other embodiments of the present invention, respectively, in which an adder Σ is added to the configuration of the first illustrated embodiment in its output circuit. It has been added.

That is, according to the embodiment shown in the second figure, by applying the output of the multiplier B to the + terminal of the adder Σ, and inputting the triangular wave input V to one terminal thereof, the transfer function of the circuit can be changed. , V ₀ =-(X ³ -4X)-X V ₀ =-(X ³ -3X). Then, a shift voltage four times as large as the input X in this case must be applied.

On the other hand, in the embodiment shown in the third figure, both the output of the multiplier B and the triangular wave input V are connected to its + terminal, and from V ₀ =-(X ³ -2X) + Specifically, the transfer function is V ₀ = -(X ³ - 3X). And in this case,
A shift voltage that is twice the input voltage is sufficient.

FIG. 4 is a circuit configuration diagram showing the improvement of high frequency characteristics of the present invention. In addition to the configuration of the first illustrated embodiment, another multiplier of the same type as multiplier A is added to the X input signal path of multiplier B. C has been inserted.

By the way, when generating a high frequency sine wave with a cube output as in the first illustrated embodiment, the triangular wave input V is directly input to the X input of the multiplier B, while the Y input is Since the multiplier A with the squarer configuration and the DC bias shifted signal are input, the signal to the Y input that has passed through many circuit elements (transistors, etc.) is the same as the previous X.
This results in a time delay compared to the input signal. Therefore, it is necessary to compensate for the time difference between these two signals.

However, this type of general-purpose analog four-quadrant multiplier is often constructed with Gilbert cells, so
It is not easy to comprehensively compensate for the variations and temperature characteristics of these elements used in combination in a circuit device.

Under such circumstances, according to the embodiment shown in FIG. 4, the path of the signal entering the X input of multiplier B is such that the path bypassing the added multiplier C circuit has the same circuit configuration as multiplier A. Because of this, the multiplier A
The signal going to the X input of multiplier B can be processed under the same operating conditions as the temperature characteristics and the like.

〔Effect of the invention〕

As described above, according to the generator of the present invention, a triangular wave input is given to the first multiplier under the squarer connection, and the square wave output from the multiplier is shifted to the negative side by the DC bias. 2 to the Y input of the multiplier, while the triangular wave input is applied to the X input of the second multiplier, the triangular wave is used as the reference frequency input, and the shift level is precisely adjusted. , shift the simulation value 0.0000034%, which can reduce the distortion rate to 0.001% or less, to a value of 3.0464808V (input
(approximately 3 times V), it is possible to obtain a cubic wave output that approximates a sine wave to the extent that there is no problem in practical use, and its circuit configuration is not sensitive to level fluctuations and always operates stably. This is promising and there is no risk of differential noise occurring.

Furthermore, by adding an adder, it is possible to configure a circuit in which the shift voltage due to DC bias is twice or four times the input voltage, and by adding a multiplier of the same type, the time of the signal system can be reduced. The generator of the present invention is extremely effective in practical use, as compensation can be performed extremely easily without consideration of troublesome temperature characteristics between used elements.

Incidentally, when the transfer function equation of the conventional sine wave generating circuit shown in FIG. 6 is factorized, it becomes as follows, and an imaginary number appears in the denominator. Follow. The generator of the present invention comprising the above-mentioned transfer function differs greatly from this conventional device in its circuit operation function.

V ₀ ≒1.5715V−0.004317V ³ /1+0.001398V
² ≒-3.0880V ³ +1124.1V/V ² +715.31 ≒-3.0880V (V ² -364.0)/V ² +715.31
≒−3.088V (V+19.1) (V−19.1)/(V+j26
.75) (V−j26.75) ≒−3.088V (V+19.0794639) (V−19.0
794639)/(V+j26.7452348)(V−j26.7452348)

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing one embodiment of the generator of the present invention, FIGS. 2 to 4 are circuit diagrams showing other embodiments of the generator of the present invention, and FIG. 5 is a circuit diagram of the generator of the present invention. FIG. 6 is a circuit configuration diagram showing an example of a conventionally known sine wave generator. A, B and C...multiplier, Σ...adder, V
...triangular wave input, V ₀ ...sine wave output, V shift
...DC bias section.

Claims (1)

[Claims] 1. A triangular wave input is given to the first multiplier under the squarer connection, and the square wave output from the multiplier is shifted to the negative side by a DC bias, and the Y of the second multiplier is
A sine wave generator characterized in that the triangular wave input is applied to the input, and the triangular wave input is applied to the X input of the second multiplier to obtain a cubic wave output that approximates a sine wave. 2. The sine wave generator according to claim 1, further comprising an adder processing the cube wave output from the second multiplier and the triangular wave input. 3. The sine wave generator according to claim 1, wherein the triangular wave input is applied to the X input of the second multiplier via a third multiplier of the same type.