KR100430791B1 - Automatic input switching circuit in accordance with control voltage - Google Patents

Abstract

The present invention relates to a circuit that automatically selects and uses two input signals according to the magnitude of a control voltage. In the conventional circuit, a low-pass filter after some time is applied because the input signal is applied with a frequency sweep. Not only has the disadvantage of saturation, but also the difficulty of measuring the integral time, making it difficult to accurately obtain data during the test.

According to the present invention, the output of the low pass filter through an integrator by automatically selecting different inputs instantaneously as the control voltage changes in a closed circuit outputs a positive DC voltage when the input frequency is greater than the reference frequency, and the input frequency is If it is smaller than the reference frequency, it configures the circuit to change output with the inclination time by the negative DC voltage, so that the inclination of the integrator output can be accurately measured and the integration time can be easily measured to solve the problem of testing. It provides an input signal automatic selection circuit according to the magnitude of the control voltage.

Description

AUTOMATIC INPUT SWITCHING CIRCUIT IN ACCORDANCE WITH CONTROL VOLTAGE}

The present invention relates to a circuit for automatically selecting and using two input signals according to the magnitude of the control voltage, in particular, according to the magnitude of the analog control voltage in the closed circuit, after selecting different inputs instantaneously, The present invention relates to an automatic input signal selection circuit according to the magnitude of the control voltage, which solves the problem of testing by accurately measuring the slope and measuring the integration time easily.

Conventional test equipment for measuring data according to the inclination of the output of the integrator includes an amplifier (1), a phase detector (2), and first to fourth low pass filters (3) (4) (5) (6). ), A voltage controlled oscillator circuit (7), a frequency divider (8), an integrator (9), and a converter (10),

The signal Va input to the amplifier 1 is applied as 5sin2π (100 + 5cos (2π0.5t) t) as Δf changes to 5Hz in a single frequency signal (100Hz).

At this time, the amplifier 1 amplifies the input signal Va while the frequency is changed, and outputs it to the phase detector 2, the phase detector 2 to the control signal of the voltage controlled oscillation circuit 7 Therefore, the phase is detected and then output to the first low pass filter 3.

The first low pass filter 3 converts a frequency change of an input signal with respect to a reference frequency of 100 Hz into a voltage and outputs the voltage to a second low pass filter 4 and an integrator 9, thereby integrating the integrator. In (9), the converted signal is integrated to output a 5 Hz sine wave signal through the third low pass filter 5, the converter 10, and the fourth low pass filter 6.

However, the conventional circuit has the disadvantage that the output of the third low pass filter 5 becomes saturated after a slight (2-3 seconds) time because the input signal is applied while the frequency sweep is applied. It is also difficult to measure time, which makes it difficult to accurately obtain data during testing.

The present invention outputs a positive DC voltage when the output of the low pass filter through the integrator by automatically selecting different inputs instantaneously as the magnitude of the analog control voltage in the closed circuit is different than the reference frequency, and the input frequency is If it is smaller than the reference frequency, it configures the circuit to change output with the inclination time by the negative DC voltage, so that the inclination of the integrator output can be accurately measured and the integration time can be easily measured to solve the problem of testing. It provides an input signal automatic selection circuit according to the magnitude of the control voltage.

1 is a circuit diagram applied in the prior art.

2 is a block diagram of an automatic input signal selection circuit according to the magnitude of a control voltage according to an embodiment of the present invention.

3 is a detailed circuit diagram of an input signal automatic selection circuit differing in magnitude of a control voltage according to an embodiment of the present invention.

Automatic input signal selection circuit according to the magnitude of the control voltage of the present invention for achieving the above object, the first and second buffer unit to which a plurality of input signals having a predetermined frequency band is input, and a variable frequency signal A third buffer unit which integrates the integrator and then inputs the voltage control signal filtered by the low pass filter; and in the third buffer unit, the first and second buffer units according to the positive and negative polarity of the voltage control signal. A comparator for converting an input signal input to the DC voltage into a form of a DC voltage and selectively outputting the DC signal; and a switching-on state when a negative DC voltage is output from the comparator, and outputting an analog signal input through the first buffer unit; 1 switch and the switching state when the positive DC voltage output from the comparator, the analog signal input through the second buffer unit And a second switch for outputting. The first switch and the second switch are configured to include a second switch when the first switch is turned on according to the polarity of the voltage output from the comparator. Is turned off, and when the second switch is turned on, the first switch is turned off. Hereinafter, a preferred embodiment of the present invention will be described with reference to the accompanying drawings. .

2 is a block diagram of an input signal automatic selection circuit according to the magnitude of a control voltage according to an embodiment of the present invention, and FIG. 3 is a detailed circuit diagram of an input signal automatic selection circuit according to the magnitude of a control voltage according to an embodiment of the present invention. to be.

As shown in FIGS. 2 and 3, the first and second buffer units 11 and 12 to which a plurality of input signals Va; 5cos2π100t (Vb; 5cos2π200t) are respectively input, and a variable voltage control signal ( The output of the low pass filter through the integrator is input according to the third buffer unit 13 to which Vcontrol) is input and the magnitude (+ 1V) (-1V) of the voltage control signal input to the third buffer unit 13. If the frequency is greater than the reference frequency, a positive DC voltage is output; if the input frequency is less than the reference frequency, a negative DC voltage is output to automatically select one of the signals input to the first and second buffer units 11 and 12. The comparator 14 and the comparator 14 to output the negative DC voltage from the comparator 14, and when the negative DC voltage is output, the signal Vb input to the second buffer unit 12 when the positive DC voltage is output. At the time of outputting a positive DC voltage from the first switch 15 and the comparator 14 operating on to determine It is but an off operation, when the DC voltage of the sound output is composed of a second switch 16 operated on to determine the signal (Va) input to the first buffer 12 to the output signal (Vout).

Hereinafter, unexplained reference numerals R1-R6 are resistors, and D1-D2 are diodes.

Referring to Figures 2 and 3 attached to the action of an embodiment of the present invention configured as described above are as follows.

First, the input signal Va (5cos2π100t) is input to the first buffer unit 11 while another input signal Vb (5cos2π200t) is input to the second buffer unit 12.

In this case, when the variable voltage control signal Vcontrol is output to the comparator 14 through the third buffer unit 13, the comparator 14 may be configured to the magnitude of the voltage control signal input to the third buffer unit 13. Accordingly, a plurality of input signals Va and Vb are automatically selected and output.

That is, when the voltage control signal input to the third buffer unit 13 is + 1V or more, that is, the output of the low pass filter passing through the integrator is greater than the reference frequency, the comparator 14 receives a positive DC voltage. Will print out,

According to the positive DC voltage output from the comparator 14, the diode D2 is turned on, and D1 is cut off so that the second switch 16 is turned on. On the contrary, the first switch 15 is turned off.

Therefore, the signal Vb input to the second buffer unit 12 among the plurality of input signals Va and Vb passes through the second switch 16 and is determined as an output signal Vout.

On the other hand, if the voltage control signal input to the third buffer unit 13 is -1V or less, that is, the input frequency passed through the integrator is smaller than the reference frequency, the comparator 14 outputs a negative DC voltage.

According to the negative DC voltage output from the comparator 14, the diode D1 is turned on and the D2 is cut off so that the first switch 15 is turned on. On the contrary, the second switch 16 is turned off.

Therefore, the signal Va input to the first buffer unit 12 among the plurality of input signals Va and Vb passes through the first switch 15 and is determined as an output signal Vout.

In other words, the present invention outputs a positive DC voltage when the output of the low pass filter passed through the integrator is greater than the reference frequency, and has an inclination time as an integration time when the input frequency is smaller than the reference frequency. By varying the output, the integrator output can be accurately measured and the integration time can be measured easily. Furthermore, as shown in the configuration circuit of the present invention, a plurality of operational amplifiers are used, so that a constant frequency band When an analog signal is inputted, it is used when a voltage of a necessary frequency band is instantaneously needed according to the frequency change of the control signal applied through the comparator 14. Therefore, the switching of the circuit of the present invention is separated into two. One reason is that it is applied through other switches due to the interference of analog signals. In order to eliminate the problem of not outputting the correct voltage due to interference in the call. Particularly, in the present invention, when an experimental value is obtained by suddenly changing from a signal voltage of a constant frequency, such as an oscilloscope, to a signal voltage of another frequency band, When the input signal from the low frequency filter is applied while swinging according to the analog waveform, the saturation state is not generated in the low frequency filter region. Can be.

As described above, the present invention automatically selects different inputs instantaneously as the magnitude of the analog control voltage having a constant frequency band in a closed loop changes, and if the output of the low pass filter passed through the integrator is greater than the reference frequency, It outputs DC voltage of, and if the input frequency is less than the reference frequency, it configures the circuit to change and output the slope with the negative DC voltage by integration time, while accurately measuring the slope of the integrator output and measuring the integration time easily. It provides the effect of easily solving the challenges of testing.

Claims (2)

First and second buffer units to which a plurality of input signals having a constant frequency band are input; A third buffer unit for integrating a variable frequency signal in an integrator and then inputting a voltage control signal filtered by the low pass filter; A third comparator for converting an input signal input to the first and second buffer parts into a DC voltage form and selectively outputting the input signal input to the first and second buffer parts according to the positive and negative polarity of the voltage control signal; A first switch which is switched on when a negative DC voltage is output from the comparator, and outputs an analog signal input through the first buffer unit; And a second switch which is switched on when the positive DC voltage is output from the comparator, and outputs an analog signal input through the second buffer unit. Selection circuit. The method of claim 1, According to the polarity of the voltage output from the comparator, the first switch and the second switch, when the first switch is turned on, the second switch is turned off, when the second switch is turned on, 1 switch is an input signal automatic selection circuit according to the magnitude of the control voltage, characterized in that the off state.