JPH0748644B2 - Waveform generator - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waveform generator capable of arbitrarily controlling the amplitude of an integrated waveform according to the frequency of an input synchronizing signal.

2. Description of the Related Art FIG. 6 shows a conventional waveform generator for generating a sawtooth wave by, for example, Miller integration and its operating waveform. If the input impedance of the amplifier 7 is ∞ and the output impedance is 0, it flows through the resistor 3. Since all the current 1 flows into the capacitor 4, e = υ _c + υ _o (1) υ _o = G _e (2) From equations (1) to (3), if ν _c and υ _o are deleted, Becomes

Therefore, FIG. 6a can be rewritten as FIG. 6c. Due to the presence of the amplifier 7, the capacitor C is apparently (1
-G) double. Since FIG. 6c shows an RC integrating circuit, the integration time constant τ _m is τ _m = (1-G) RC (5).

It can be seen that if G is −∞, τ _m is ∞. Even if G is not -∞, it is a sufficiently large negative value, and if τ _m >> t can be considered, then e in FIG. In, since τ can be replaced by τ _m , Becomes

Therefore, according to the equations (2) and (6), the output υ _o is represented by the operation waveform shown in FIG. 6b. Becomes

That is, although the integration time constant is (1-G) times that of the simple RC integrating circuit, the output υ _o does not become small. FIG. 7 shows an example of a Miller integrating circuit configured by using transistors. The input stage transistor 10 has an emitter follower for increasing the input resistance, and the output stage transistor 12 has an emitter follower for reducing the output resistance. Therefore, the amplifier including the transistor 11 is used in the active region of the transistor. It is assumed that the input υ _i shown in FIG. 7b has a positive voltage sufficient to saturate transistor 11. Incidentally. When υ _i suddenly goes to a negative voltage, transistor 11 transitions from the saturated state to the active state. Then, the collector voltage of the transistor 11 starts to rise, and this is fed back to the base of the transistor 10 via the emitter follower 12. Therefore, the transistor 11 cannot be immediately turned off, and the entire transistor operates as a Miller integrator to output the sawtooth wave shown in FIG. 7c.

Problems to be Solved by the Invention However, in the above configuration, the amplitude of the sawtooth wave does not change from the pulse width, but when the synchronizing signals with different frequencies are input as shown in FIG. It had a problem that it was not always constant.

In view of the above point, the present invention has an object to provide a waveform generation circuit capable of arbitrarily controlling the amplitude of an integrated waveform according to the frequency of an input synchronization signal.

Means for Solving the Problems The present invention includes an integrating means for integrating a synchronizing signal, a frequency-voltage converting means for converting the synchronizing signal into a frequency-voltage, and a gain controlling means for controlling a gain of a signal from the integrating means. Detecting means for detecting the signal amplitude from the gain control means,
A waveform provided with a comparison means for comparing the detection signal from the detection means with a signal from the frequency-voltage conversion means, and a control means for supplying the signal from the comparison means to the gain control means to control the gain. It is a generator.

Action The present invention has the above-described configuration to integrate the input synchronization signal,
After passing this integrated signal through the gain control circuit, its signal amplitude is detected. A comparator compares the detection signal and an F-V converted signal of the input synchronizing signal, and the comparison output is fed back to the gain control circuit, so that the integrated waveform varies according to the frequency of the input synchronizing signal. Waveform generator that can control the width arbitrarily.

Embodiment 1 FIG. 1 is a block diagram of a waveform generator according to a first embodiment of the present invention. In FIG. 1, 14 is a Miller integrating circuit for performing the Miller product, 20 is a frequency-voltage conversion circuit for converting the input synchronizing signal into a frequency-voltage, 15 is a gain control circuit for controlling the gain, 16 is a signal amplitude detection for detecting the signal amplitude. A circuit, 18 is a comparator 1 for comparing the signal amplitude detection output with the signal from the frequency-voltage conversion circuit.

The operation waveform diagram of FIG. 2 will be used to explain the operation of the waveform generator of this embodiment having the above-described configuration. Note that the case of generating a sawtooth wave will be described for the sake of clarity.

When the synchronizing signal of frequency ₁ shown in FIG. 2 (a) is supplied to the input terminal 13 and integrated by the Miller integrating circuit 14, a sawtooth wave of amplitude V ₁ shown in FIG. 2 (b) is output. In addition, when ₂ = 2 ₁ shown in FIG.
The amplitude shown in Fig. 2 (d) when integrated by A sawtooth wave is output, and the amplitude of the sawtooth wave changes greatly depending on the input frequency. So Miller integrator circuit
Gain control circuit 15, signal amplitude detection circuit
16, the feedback loop gain control circuit 19 composed of the comparator 1 18 controls the gain control voltage V _GC of the gain control circuit 15 according to the frequency, and also controls the comparator 1 18 by the frequency-to-voltage converted voltage. Output terminal 17
Generates a sawtooth wave whose amplitude can be controlled arbitrarily according to the frequency. The integrated waveform from the Miller integrating circuit 14 is supplied to the gain control circuit, and then the signal amplitude detecting circuit 16 detects the signal amplitude. The signal amplitude detection circuit 16 is composed of a peak detection circuit and the like, and as shown in FIG. 2B, when the input frequency is ₁ , a signal corresponding to the signal amplitude V ₁ of the integrated waveform is detected. Further, as shown in FIG. 2 (d), when the input frequency is ₂ = 2 ₁ , the signal amplitude of the integrated waveform is A signal corresponding to is detected. This signal amplitude detection circuit 16
The detection signal corresponding to the signal amplitude from is supplied to the comparator 118 and compared with the signal from the frequency-voltage conversion circuit 20. The comparison output V _GC from the comparator ₁₁₈ is supplied to the gain control terminal of the gain control circuit 15, and the gain is controlled according to the input frequency.
A sawtooth wave having an amplitude V ₃ = V ₄ shown in (f) is output, and a sawtooth wave having a substantially constant amplitude is generated for synchronizing signals having different frequencies.

Next, in order to explain the operation of supplying a signal from the frequency-voltage conversion circuit 20 to the comparator 1 to perform arbitrary gain control, the characteristic diagram of signal amplitude versus frequency of FIG. 3 is used.

When the signal from the frequency-voltage conversion circuit 20 is an FV conversion voltage which is substantially constant with respect to frequency, the output signal amplitude is always constant with respect to frequency as shown by the solid line in FIG. 3 (a). Become. Further, when the signal from the frequency-voltage conversion circuit 20 is an FV conversion voltage proportional to the frequency, the output signal amplitude increases proportionally to the frequency as shown by the broken line in FIG. 3 (c). Become.

Needless to say, when the gain control by the feedback loop is not performed, the signal amplitude greatly changes non-linearly with respect to the frequency as shown by the alternate long and short dash line in FIG. 4 (b).

As described above, according to this embodiment, in the feedback loop gain control circuit 19, the input synchronizing signal is frequency-
Even if the amplitude and pulse width of the input synchronizing signal changes by inputting the voltage F-V converted by the voltage conversion circuit 20 to the reference potential V _REF1 of the comparator ₁₁₈ and controlling the gain of the feedback loop, It is easy to always generate an integrated waveform of the signal amplitude corresponding to the frequency.

FIG. 4 is a block diagram of a waveform generator showing a second embodiment of the present invention. In the figure, reference numeral 21 designates a comparator 2, which operates in the same manner as in FIG. The difference from the configuration of FIG. 1 is that a sawtooth wave is input to the input terminal 13 to create a parabolic wave of substantially constant amplitude,
This parabola wave is compared with the reference potential V _REF2 by the comparator _221, and pulses having the same pulse duty ratio are created.

The operation waveform diagram of FIG. 5 will be used to explain the operation of the waveform generator of the third embodiment configured as described above. A sawtooth wave signal having frequencies ₁ and ₂ = 2 ₁ shown in FIGS. 5A and 5B is supplied to the input terminal 13, and the feedback loop gain control circuit 19 causes the sawtooth wave signal.
The output terminal 17 outputs a parabolic wave having a constant amplitude shown in FIGS. 5 (c) and 5 (d). The parabolic number of constant amplitude from the gain control circuit 15 is supplied to the comparator 221 and the reference potential.
As shown in FIG. 5 (e), the output terminal 22 is compared with V _REF2 .
As shown in (f), signals having the same pulse duty ratio are output.

As described above, according to this embodiment, the sawtooth wave signal is input, the feedback loop gain control circuit 19 creates a parabolic wave having a substantially constant amplitude, and the parabolic wave having the constant amplitude is applied to the reference potential by the comparator 222. By comparing with V _REF2 , it is possible to easily generate a pulse waveform with the same pulse duty even if the frequency, amplitude, and pulse width of the input synchronization signal change.

In this embodiment, the integrating circuit 14 is Miller integrating, but other integrating circuits may be used.

Further, in this embodiment, for example, a frequency-voltage conversion circuit
Although 20 has been described as being linearly proportional to the frequency, it may be controlled by an FV conversion signal having other characteristics such as linearly inversely proportional or curvilinearly changing.

EFFECTS OF THE INVENTION As described above, according to the present invention, it is possible to easily generate the integrated waveform of the signal amplitude always corresponding to the frequency even when the frequency, amplitude and pulse width of the input synchronizing signal are different. Further, by the gain control by the feedback control loop, the integration time constant and the amplitude fluctuation in each circuit system can be eliminated to generate a stable integration signal. Further, since the amplitude of the integrated signal can be arbitrarily controlled according to the frequency of the input synchronizing signal by arbitrarily setting the characteristics of the converted signal obtained by frequency-voltage converting the input synchronizing signal, it can be applied to the waveform generation in a wide range.

In addition, it is a very effective means for generating correction waveforms such as geometric distortion and convergence of a multi-scan receiver corresponding to various scanning frequencies, and its practical effect is great.

[Brief description of drawings]

FIG. 1 is a block diagram of a waveform generator in one embodiment of the present invention, FIG. 2 is an operation waveform diagram of the same embodiment, FIG. 3 is an operation characteristic diagram of the same embodiment, and FIG. 4 is another embodiment. 5 is a block diagram of an example waveform generator, FIG. 5 is an operation waveform diagram of the same embodiment, FIG.
FIG. 7 is a block diagram and operation waveform diagram of a conventional waveform generator, and FIG. 7 is a concrete circuit configuration and operation diagram of the conventional waveform generator. 14 ... Miller integrator circuit, 15 ... Gain control circuit, 16 ... Signal amplitude detection circuit, 18 ... Comparator 1, 19 ... Feedback loop gain control circuit, 20 ... Frequency-voltage conversion circuit.

Claims (1)

[Claims] 1. An integrating means for integrating a synchronizing signal, a frequency-voltage converting means for frequency-voltage converting the synchronizing signal, a gain controlling means for controlling a gain of a signal from the integrating means, and a gain controlling means. Detecting means for detecting the signal amplitude of, the comparing means for comparing the detection signal from the detecting means, and the signal from the frequency-voltage converting means, and the signal changing according to the input frequency from the comparing means. And a feedback control loop configured to include the gain control means, the detection means, and the comparison means, which feedback control the gain of the signal from the integration means according to the input frequency. Waveform generator.