JPS5884507A - Multivibrator circuit - Google Patents

Abstract

PURPOSE:To attain the frequency modulation and demodulation with one circuit, by providing a switch means for the base of transistors(TR) of differential constituted and switching the state being whether astable or monostable, in an emitter coupling type multivibrator circuit. CONSTITUTION:TRs Q11-Q21 and a capacitor C constitute an emitter coupling type multivibrator and TRs Q18, Q19 form a differential type current switching circuit. TRs Q5-Q8 constitute a switch means which switches the multivibrator into an astable or a monostable type. At modulation, a control voltage applied to control input terminals 15 and 16 goes to L and H respectively and TRs Q11 Q20 are operated as a voltage estable multivibrator together with a feedback circuit consisting of TRs Q6-Q7, and TRs Q9-Q10. At demodulation, the control voltage to the terminals 15, 16 are inverted and TRs Q11-Q21 are operated as a monostable multivibrator taking the base of the TRs Q5, Q6 as a trigger input terminal.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to frequency modulation/demodulation 11M of a magnetic recording/reproducing device, for example.
BACKGROUND OF THE INVENTION In a magnetic recording/reproducing device (hereinafter referred to as a VTR), when recording a video signal on a magnetic tape, the luminance signal and color signal are first separated. , the luminance signal is low-carrier [FM modulated], while the color signal is low-frequency converted, and then both signals are superimposed.Also, during playback, the reproduced signal obtained via the magnetic head is converted into a low-carrier FM signal. FM demodulation and frequency conversion are performed on each signal, and then both signals are superimposed to obtain a reproduced decoded video signal. Here, the luminance signal is recorded and the FM modulation during reproduction is performed. , F.M.
Conventionally, demodulation is performed using K1m as shown in Figures 1 and 2, respectively.
The 0I11 diagram that was performing 1 and 16 operations is FM modulation at
In the diagram shown, astable multivibrator (1) tV
It is used as a cO (voltage controlled oscillator) and outputs a nine-frequency liquid proportional to changes in the voltage of the input video signal to perform FM modulation. Figure 2 is a four-dimensional diagram showing the amount of FM demodulation, and shows the output obtained through the input FM signal tVt (ty,) and the output that is further passed through a pulse-sharpening circuit using a monostable multivibrator (0). Multiply by the obtained output - (4)
Demodulation is performed by multiplying by .@Problems with background technology As mentioned above, the FM modulation and demodulation operations in conventional VTRKs are performed in independent circuits, and the number of elements used is large, making it difficult to implement integrated circuits. However, it has the disadvantage that the number of Kit bins increases if

The present invention is based on the above-mentioned considerations, and switches between two types, an astable type and a monostable type, and when this is used in a liquid number modulation circuit and a recirculating I11 circuit, these can be combined into one. It is an object of the present invention to provide a multivibrator circuit which has the following features: can be assembled into two circuits and is suitable for integrated circuit implementation.

Examples of the invention The present invention will be explained below based on illustrated embodiments.

The third WJ is a diagram showing an example in which a multivibrator circuit with zero to 11 is applied to a frequency modulation/demodulation circuit.

Here, Qs to Qzx are transistors, R1 to R and R are resistors, D is a diode, and C is a capacitor.

O9 (10), α1) is the input terminal, a smell electric vine circuit, α3) is the multiplier, α4) is the low-pass y4le fi (L
PF) Terror F), (15), (16) C are control input terminals.

The platform circuit Q2) has two output terminals aη, (18
), and the configuration is such that signals with mutually opposite phases are output. Further, C10) and (20) are voltage sources, and (21) and (2) are output terminals.

In the above circuit, the transistor Q1 to 31 and the capacitor C constitute a construction type multivibrator, and the transistors Q1g and Qllll constitute a differential current switching circuit.

Further, the transistors Qs, Q@, Qt, and Qs constitute a switch means for switching the constructional ivy type multivibrator to an astable type or a monostatic type.

Next, the operation of the 31st circuit during frequency modulation and demodulation will be explained.

First, the operation during modulation is tanned. In this case, the control voltage applied to the control input terminal Q5) (referred to as v6) is at a low level, and the control voltage applied to the control input terminal α6) (referred to as vc) is at a high level. . Therefore, transistors Qt and QzwQ3 are OFF and FFSQ4 is ON. It also controls the control voltage V @ the limiter circuit α and the multiplier α3), and in this case, stops these operations and also outputs the output terminal αη of the limiter circuit Cl2).

(18) to reduce the DC bias of the output.

Through the above-described operation, the transistor Qb.

Qs+Qst is cut off and therefore transistor Q
The two constant vine-coupled multivibrator consisting of 11 to 9 ports is transistor QstQy, Q reference *Qt.

Together with the feedback circuit formed by this, a voltage-controlled astable multivibrator is constructed. Therefore, lll13
The circuit shown in the figure is a frequency modulation circuit.The above details will be explained in more detail with reference to FIG. Fig. 4 is a diagram showing the axillary tube of the main part of the circuit shown in Fig. 3. In this figure, (1), (b), ((+), i The ivy waveforms are shown respectively.

In the period Ta shown in the diagram, the current path is transistor Qst-#transistor Q1]→endenna C→transistor Q1m-to-transistor Qs.

Therefore, in the period Tb, the current path in the circuit of FIG. 3 is transistor Qll -> transistor Qts - tanden tC -f transistor Q19 -> transistor Q! It becomes 〇. Therefore, over both periods 'r, ,'rb, the transistor Q
me K becomes 0 where collector current I@lIQ flows.
Here, Vref is equal to the power supply voltage CE. Collector current Ies of tractor resistor 9O.

Since there is an OVa relationship between the modulated input (luminance signal) voltage UMI applied to the input terminal 0, Equation (2) becomes 1. Note that VBll (1 is the voltage between the base and the construction terminal of the transistor Q!) Therefore, the 113110 circuit becomes a frequency modulation circuit, and the nine luminance signals input from the input terminal a are output from the output terminal I.
It is FM modulated and output.

Next, the demodulation operation will be explained.

In this case, the voltage VC at the control input terminal αω is at a high level, and the voltage at the control input terminal U@ is at a low level.
Therefore, transistor Qt+QssQ3 is ONl and transistor q4 is OFF.Since it is more than 0,
Transistor Qme is cut-off, and on the other hand, the base voltage of transistor Q6゜9 is equal to the two output voltages of the circuit α (therefore, transistor Qs*Qa
The base voltage becomes sufficiently lower than 6), and the transistors Q and eQy are cut off.
1 Therefore, the transistors (ht to Qts and Qt
The multivibrator is a monostable I multivibrator with the bases of the transistors Qi and Q$ as trigger input terminals, and constitutes a pulse delay circuit. A KFM demodulator is constructed together with the multiplier α and the multiplier α.The above operation will be explained in detail with reference to the 5th garden. II
I, (aL) in this figure (b) represents each base wave type of transistors Qs and Qi, (0), (d), (・).

(f) is the transistor Qxt+Qtma・QtatChi
Each of the Ivy IN types, and 葎) indicate the output waveform of multiplication II (13), respectively.

In a stable state, either the pair of transistors Qts, (hs or the pair of transistors Q>t*Q** is OFF, and the capacitor CKti current does not flow.Transistors Ql-1Qls are OFF, In a stable state, when a high level pulse is applied to the base of the transistor Qs and a low level pulse is applied to the base of the transistor Qs, the transistor (hs
laON and Ql building will be OFF. Therefore, this and S
O current path is transistor Q1 → transistor Q17- → capacitor tC- → -transistor Qts-J) transistor Qz
t (period T8 in FIG. 5). Charging of capacitor C progresses and transistor Ql so Ql 7 is inverted,
When the transistor Q1- is turned on, it becomes stable again and no current flows through the capacitor C (period To in Figure 1). When a high-level pulse is applied to the base of the transistor Q-, the transistor Q- is turned ON.
Therefore, the current at this time is transistor Q11-7 transistor Ql@-w capacitor tC-→transistor 9 1-7) transistor Qz
0 capacitor C flowing with t (part of period T in Fig. 5)
As charging progresses, transistor (hs+Q1t is inverted and transistor Q17 is turned on, the state becomes stable again (
(period TF part in FIG. 5).

Therefore, the output pulse of the Mituta circuit negative powder obtained at the emitter of the transistor Qx4 + Qti becomes a pulse that is delayed only during the period when the capacitor CK current is flowing ◇ Multiplication of this pulse and the output pulse of the 91 Tsuta circuit 0 terminal By using the multiplication circuit (13:), the pulse of the pre-delay period becomes
! 1 collector current. If the R wave number of the demodulated input signal from the input terminal (11) at ζζ is FDI, LPF'
becomes. However, the amplitude (psak to P@11'') of the output pulse of the V company multiplier (13) is equal to the value.

(5) Substituting Take into equation (6), we get becomes.

Therefore, the circuit of FIG. 3 becomes an FM demodulator, and the input terminal e
The frequency of the FM signal input from the LPF (11) is converted into a voltage change and output from the LPF (14) to the output terminal body.

As stated above, according to the present invention, it is possible to provide a multivibrator circuit that can be switched between two types, an astable type and a monostable type, and by using this multivibrator circuit, frequency modulation and demodulation operations can be performed in one circuit. It can be done with

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a conventional FM modulator 1111, Fig. 2 tlJ- is a block diagram showing a conventional FM demodulator, and Fig. 3 is a block diagram showing a conventional FM demodulator.
The figure is a diagram showing an embodiment in which the one multi-by-peater circuit according to the present invention is applied to a frequency modulation/demodulation circuit.
Figure 4 and #I5 are #13 during modulation, modulation, and demodulation.
FIG. 7 is a diagram showing a tIIi type of the main part of the leap circuit. C...Condenna, Q! I~Q31...transistor. 1 representative Patent attorney Kensuke Chika (1 other person)

Claims (1)

[Claims] The capacitors of the first and second transistors are connected to each other via a capacitor, and the third and fourth transistors of the differential configuration are connected to each other via a capacitor.
) In a multivibrator circuit of the construction type in which the collector of the y transistor is connected to the emitters of the first and second transistors respectively, the bases of the third and fourth transistors are connected to the bases of the third and fourth transistors; The switch means forms a feedback loop that feeds back the output of the multivibrator circuit to the bases of the third and fourth transistors, making the multivibrator circuit astable, or triggers the bases of the third and fourth transistors. A multivibrator circuit characterized in that the multivibrator circuit is switched between being monostable or monostable by applying an input force.