JPH0388413A - Voltage controlled oscillator - Google Patents

Abstract

PURPOSE:To prevent the deterioration in the linearity of the oscillating characteristic by allowing a 2nd current source to apply charge/discharge operation to a capacitor in place of a 1st current source for a delay period even when there is a delay in the operation of a 1st switch circuit. CONSTITUTION:Since a 1st switch circuit comprising transistors(TRs) Q3, Q4 and a 2nd switch circuit comprising TRs Q14, Q15 are controlled by a same oscillation signal, a collector current Io of a TR Q5 being a 1st current source and a collector current Io' of a TR Q16 being a 2nd current source are switched synchronously with each other. Thus, even when the timing switching the 1st current source is retarded, the 2nd current source applies charge/discharge of the capacitor instead for the delay period. Thus, the linearity deterioration in the oscillation characteristic due to the delay in the switching timing is prevented.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides F
The present invention relates to a voltage controlled oscillator suitable for use in M modulators and the like.

[Conventional technology]

Conventionally, as a voltage controlled oscillator used in an FM modulator of a VTR, one is known that is effective in preventing the generation of the second harmonic of a carrier wave, as disclosed in, for example, Japanese Patent Publication No. 52-24370. Hereinafter, such a conventional voltage controlled oscillator will be explained with reference to FIGS. 5 to 8.

FIG. 5 is a circuit diagram showing such a conventional voltage controlled oscillator, in which Ql to Q13 are transistors, C1 is a capacitor, R1 to R3 are resistors, AI and A2 are current sources, vcc is a voltage source, and 1 is an input terminal. , 2 are output terminals.

In the same figure, a capacitor C1 is connected between the emitters of transistors Ql and Q2 that constitute an astable multi-high break.
is connected to the transistor Ql.

The emitter of Q2 is connected to the transistor Q3.Q2 which constitutes the first switch circuit. Each is connected to the collector of Q4. Transistor Q3. The terminals of Q4 are commonly connected to the collectors of transistors Q5 constituting the first current source. The terminal of this transistor Q5 is grounded via a resistor R1, and the base of the transistor Q5 is connected to the input terminal 1.

Transistor Q1. The collector of Q2 is connected to the voltage source VCC through resistors R2 and R3, which serve as loads, and the base and collector are also respectively connected to the emitters of transistors Q6 and Q7 connected to the voltage source V((). Further, the collector of the transistor Q1 is connected to the base of the transistor Q8, the collector of the transistor Q2 is connected to the base of the transistor Qll, and the collectors of the transistors Q8 and Qll are respectively connected to the voltage source VCC.The emitter of the transistor Q8 is connected to the base of the transistor Q8. , is connected to the base of transistor Q2, and is grounded via transistor Q9.QIO, whose base is connected to the collector and operates as a diode, and current fAA1, and the industrial ivy of transistor QIO is connected to the transistor Q9.
It is connected to the base of 3.

The emitter of the transistor Qll is connected to the base of the transistor Q1 and the output terminal 2, and the transistor Q12. It is grounded via Q13 and current source A2, and the base of transistor Q4 is connected to the emitter of transistor Q13.

The operation of such a voltage controlled oscillator will be briefly explained below.

Assuming that the current flowing through the collector of transistor Q5 is 1, this current I. is a transistor Q3. which constitutes a switch circuit. It can be switched to Q4.

In the first state where the transistor Q1 is on, a current flows through the path from the transistor Ql to the capacitor C1 to the transistor Q4 (this period is T), and in the second state where the transistor Q2 is on, A current flows through the path of transistor Q2-capacitor C1-transistor Q3 (this period is defined as T2).

Oscillation is sustained by repeating these two states alternately, and the same current 10 is switched and used for charging and discharging the capacitor C1 in these first and second states, thereby increasing the duty ratio. 1 (ie, T + = T 2 ) to prevent the generation of second harmonics.

Further, assuming that the capacitance value of the capacitor CI is C, and the oscillation amplitudes fed back to the bases of the transistors Ql and Q2 are both equal and ΔV, the oscillation frequency f is expressed by the following equation.

Of−・・・・・・・・・(1) 4CΔV The oscillation amplitude ΔV is determined by the resistance R2 serving as the load in Fig. 5.
, R3, the amplitude is limited by the transistors Q6 and Q7 added across the transistors Q6 . In the range where Q7 operates as a diode, the voltage between its base and the terminal is 11. Then, ΔV = V m t, and the above equation (1) becomes the following equation: 0 f-... (2) CVlli Current I flowing through the collector of transistor Q5.

changes depending on the signal voltage input from input terminal 1, so as shown in equation (2) above, output terminal 2 receives an oscillation signal a whose frequency f changes according to the input signal voltage. can get.

[Problem to be solved by the invention]

By the way, in recent years, home VTRs have been
As a result, a new system is beginning to become popular in which the FM carrier frequency of the FM signal is higher than that of the conventional system and the modulation width is also wider. In order to be compatible with both the conventional system and the new system described above, such a home VTR can oscillate over a wide range from the low frequency of the conventional system to the high frequency of the new system as an FM modulator, and at the same time, its oscillation characteristics However, as shown in characteristic (1) shown in FIG. 6, a voltage controlled oscillator is required whose oscillation frequency changes linearly with respect to the manually applied signal voltage. This is because if the linearity of the oscillation characteristic of the FM modulator deteriorates, the signal obtained by demodulating the FM signal will be different from the original signal before FM modulation.

However, in the conventional voltage controlled oscillator shown in Figure 5,
Its oscillation characteristics change as the oscillation frequency increases.
As shown in the characteristic (2) shown in the figure, the characteristic draws a gentle curve, resulting in the disadvantage that the linearity of the oscillation characteristic deteriorates. This will be explained in detail below.

First, one of the causes of deterioration of the linearity of oscillation characteristics is
In FIG. 5, there is an operation delay of the switch circuit composed of transistors Q3Q4, which will be explained using FIG. 7. Note that FIG. 7 shows the operating waveforms of each part in FIG. 5, where a is the oscillation signal output from the output terminal 2, 11.12 is the current flowing through the collector of the transistors Q3 and Q4, and b is the current flowing through the collector of the transistors Q3 and Q4. The waveform of the emitter potential of the transistor Q1 is the waveform of the emitter potential of the transistor Q2.

First, before time t, transistors Ql, Q
4 is off, transistor Q2. Assuming that Q3 is on, at this time the current 1 is the transistor Q2
→Flows through the path of capacitor Cl-1-transistor Q3,
The emitter potential of the transistor Ql drops with time.

Eventually, at time t, the emitter potential of the transistor Ql becomes smaller than the emitter potential C of the transistor Q2, with the oscillation amplitude Δ
When the potential becomes lower by V, current begins to flow through the transistor Q1, the states of the transistor Ql are reversed from off to on, the transistor Q2 is reversed from on to off, and the level of the output signal a is also reversed from Lo-level to High level. Sur.

This state reversal is caused by the transistor Q3. The current I is also transmitted to the base of Q4. If there is a delay of time τ1 before switching, the current I. (transistor Ql-) flows through the path of transistor Q3 and does not flow to capacitor C1.

Therefore, the emitter potential C of the transistor Q2 does not change until the time t2 when this time τ has elapsed.

0 Eventually, at time t2, the current I. When is switched, current I flows through the path of transistor Q1 → capacitor C1 → transistor Q4. flows, and the emitter potential C of transistor Q2 drops. Then, at time t, when the emitter potential C of the transistor Q2 becomes a potential lower by ΔV than the emitter potential of the transistor Q1, the state of the transistor Ql is reversed from on to off, and the state of the transistor Q2 is reversed from off to on. , as described above, the period τ during which the switching operation of transistor Q3.04 is delayed,
That is, until time t4, current I0 flows through transistor Q2.
→Since it flows through the path of transistor Q4, the voltage across the transistor Q1 does not change. And time t4
Then, current I0 flows from transistor Q2 → capacitor C
1→l・Flows through the path of transistor Q3, and passes through transistor Q
The electric potential decreases over time. At the next time t, the same operation as at time t1 is repeated.

Time point 1. The time from time t:l to time t:l is equal to the time from time t31 to time t5, and from this, the oscillation frequency f is determined by the following equation.

2 (τ++T+) Here, T1 is the time from time t2 to time t, and is expressed by the following formula.

i.

As is clear from the above equation (3), when the oscillation frequency f is low, the value of the charging/discharging time T of the capacitor C8 is large, and the delay time τ1 of the switch timing can be ignored. However, when the oscillation frequency f is The charging/discharging time T1 becomes smaller as the temperature increases, and the switch timing delay time τ
1 cannot be ignored. In this case, the oscillation characteristic is l/(2
The curve saturates at a frequency of τ1), and therefore the linearity of the oscillator deteriorates.

In FIG. 5, another cause of deterioration of the linearity of the oscillation characteristics is a change in the oscillation amplitude ΔV.

2 That is, as shown in equation (2) above, the oscillation frequency f
To change the current I depending on the input signal voltage. This current I must be increased or decreased. Due to the increase or decrease in
Transistor Q6 for limiting oscillation amplitude. The current flowing through Q7 also changes. Therefore, if the current is increased by 1° in order to raise the oscillation frequency, the transistor Q6.
The current flowing when Q7 is turned on also increases, which causes these transistors Q6. The base-to-pin voltage VIIE of Q7 also increases. Therefore, as is clear from equation (2) above, the oscillation frequency f becomes lower than when the base-emitter voltage V1 is constant, and the current I. As f increases, the rate at which the oscillation frequency f decreases increases. This causes deterioration in linearity.

Furthermore, a transistor Q6. which limits these oscillation amplitudes.
As shown in FIG. 8, Q7 blunts the rising edge of the oscillation signal a, which causes the problem that the duty ratio shifts and second harmonics are generated. The reason why the rising edge of oscillation signal a is dull is because of transistor Q2.
When Q2 is reversed from on to off, the collector potential of transistor Q2 begins to rise;
This is because when 7 is turned off, a rising waveform occurs in accordance with the time constant due to the junction capacitance between the base and emitter and the load resistance R3.

Conversely, when transistor Q2 flips from off to on, the current I. As a result, the collector potential of the transistor Q2 suddenly drops to a potential lower than the voltage source Vec by VIF. In particular, the higher the oscillation frequency f, the higher the current I. increases and the fall speed is accelerated, whereas the rise time of the oscillation signal a remains unchanged, so as the frequency becomes higher, the generation level of the second harmonic also increases.

SUMMARY OF THE INVENTION An object of the present invention is to provide a voltage controlled oscillator that solves these problems and maintains linearity of oscillation characteristics over a wide range of oscillation frequencies.

[Means to solve the problem]

In order to achieve the above object, the present invention includes a 1.4 second transistor, a 1.4 second transistor, and a first. a capacitor connected between the emitters of the second transistor; a first current source that generates a current whose magnitude changes depending on the input signal voltage; a voltage controlled oscillator comprising: a first switch circuit that alternately selects the output of a second transistor and connects it to the first current source; a second current source generating a varying current;
Said 1st. and a second switch circuit that alternately selects the emitters of the second transistors and connects them to the second current source.

[Effect]

When the first transistor is on and the second transistor is off, the first current source is connected to the emitter of the second transistor by the first switch circuit, and the second current source is connected to the emitter of the second transistor by the first switch circuit.
The current source is connected to the epitome of the first transistor by a second switch circuit. At this time, the current of the first current source flows through the first transistor and the capacitor to charge and discharge the capacitor, and the current of the second current source flows only to the 51st transistor. Next, when the first transistor turns off and the second transistor turns on from this state, the first... Even if the first current source is not switched by the delay time of the second switch circuit,
Since the second current source linked to the first current source is connected to the emitter of the first transistor, the current of the second current source is transferred from the second transistor to the capacitor instead of the first current source. The capacitor is charged and discharged.

Therefore, even if there is a delay in the operation of the first switch circuit, the second current source charges and discharges the capacitor instead of the first current source during this delay period. There is no linearity deterioration.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram showing an embodiment of a voltage controlled oscillator according to the present invention, in which Q14 to Q20 are transistors.
4 to R6 are resistors, A3 is a current source, and 6 (1) is a voltage source. Portions corresponding to those in FIG. 5 are given the same reference numerals and redundant explanations will be omitted.

In the figure, transistor Q14. q154;t Their emitters are commonly connected to form a second switch circuit, the base of transistor Q14 is connected to the base of transistor Q4, the base of transistor Q15 is connected to the base of transistor Q3, and transistor Q
The collector of transistor Q14 is connected to the emitter of transistor Q1, and the collector of transistor Q15 is connected to the epitome of transistor Q2. Transistor QI4. Q15
The commonly connected emitters of are connected to the collector of a transistor Q16 constituting a second current source, and the terminals of the transistor Q16 are grounded via a resistor R4.

Further, the base of this transistor Q16 is connected to the input terminal l together with the base of the transistor Q5.

The emitter of transistor Q17 is connected to the collector of transistor Ql and the base of transistor Q2, and 1-
The emitter of transistor Q18 is connected to the collector of transistor Q2 and the base of transistor Q19. The bases of transistors QI7.Q18 are both connected to the voltage source V, and the bases of transistors QI7. Q1B
The collectors of both are connected to a voltage source VCC, respectively. The emitters of transistors Q19 and Q20 are commonly connected and grounded via current source A3. Further, the collector of transistor Q19 is connected to voltage source V via resistor R5.
cc and is also connected to the heel of transistor Q8, and the collector of transistor Q20 is
Voltage source ■ through resistor R6. , and also connected to the base of transistor Qll.

Next, the operation of this embodiment will be explained using FIG. 2. However, FIG. 2 is a waveform diagram of signals at each part in FIG. 1, and signals corresponding to those in FIG. 1 are given the same symbols.

In FIGS. 1 and 2, transistors Q3 and Q4
The first switch circuit and transistor Q14. Q
15 is controlled by the same oscillation signal, so that the collector current I of transistor Q5, which is the first current source. and transistor Q, which is the second current source.
16 collector current I. ′ can be switched synchronously.

When the oscillation output is reversed from high level to low level at time t1 in FIG. 2, transistor Q1 changes from on to off, and transistor Q2 changes from off to on. At this time point t, the first. Since the delay time of both the second switch circuits is τ1, the operation is not switched, and the transistor Q3 is off and the transistor Q4 is on. Similarly, the transistor Q14 is on, the transistor Q15 is off, and the collector current I of the transistor Q16, which is the second current source. ' flows as a current I through the transistor Q14. This causes this current ■. ' flows through the path of turned-on transistor Q2→capacitor C1→transistor Q14, so that the current potential of transistor Q1 decreases over time from time t1. Then, at time t2, which is delayed by time τ1 from time 9 tl, transistor Q3. Q15 is turned on, transistor Q4. Q14
When is turned off, current 1°' flows through the path from transistor Q2 to transistor Q15 and no longer flows to capacitor CI.
5 flows through the path of transistor Q2 → capacitor C1 → transistor Q3, so at time t2
From is the current I. Therefore, the emitter potential of transistor Q1 decreases with time.

At time t3, when the epitaxial potential of transistor Q1 drops by 2ΔV, the oscillation signal a is inverted from the Lo level to the High level. Second
Delay time τ1 until time t when the switch circuit operates
In the period of , the current of the second current source ! . ' becomes a current 4 in the transistor Q15, which flows through the path from the transistor Ql to the capacitor C1 to the transistor Q15, and the emitter potential C of the transistor Q2 drops with time, and at time t4, the current becomes the first . When the second switch circuit switches 0, the current I of the first current source. flows through the path of transistor Q1→capacitor C1→transistor Q4, causing the emitter potential C of transistor Q2 to continue to drop.

By the above operation, in FIG. 1, if the resistance values of the resistors R1 and R4 are made equal, l0=I.

Therefore, if the potential from time t to time t3 is then time t3
The potential C from t to time t falls at the same constant slope. From this, the time from time t1 to time t3 is T
,' is expressed as 0 (however, 10"10'), and the oscillation frequency f in this example is 2T,
4CΔV, and the oscillation frequency f is 1.4CΔV. It is not affected by the delay time τ1 of the second switch circuit. That is, in this embodiment, transistor Q3. Even if there is a delay in the current switching operation in the switch circuit consisting of Q4, the linearity of the oscillation characteristics will not deteriorate because it will not be affected.

By the way, in the prior art shown in FIG. 5, as explained above, the transistors Q6 . Q
7, the linearity of the oscillation characteristics deteriorated and second harmonics were generated.However, in this embodiment, transistors Q17. Q1B are connected, and these transistors Q17. Transistors Q20 . The bases of transistors Q19. It is configured to take out an oscillation signal with an oscillation amplitude ΔV from the collector of Q20, thereby making it possible to limit the oscillation amplitude without requiring diode characteristics between the base and emitter of the transistor.
This prevents deterioration of the linearity of the generation characteristics and generation of second harmonics.

That is, in FIG. 1, transistors Q17 to Q2
The circuit consisting of transistors Q17.0 is a current amplification circuit shown in FIG. The currents flowing through Q1B are respectively il=lsz, and transistors Q19Q20
If the current flowing in each is Ill + Ill, then Is
l: l52= 1++: I tz ---(7
) is established. I transistor Q17. Q18
The current I Sl, r 52 flowing through the transistor QIQ2 changes from 0 to (1011,'
).

Here, when transistor Q1 is off and transistor Q2 is on, Isl-〇, 1. ,. -I. +1°, and if the current value of current source A3 is 11, then from the above equation (7), 1°-0,112=IL.

Assuming that the resistance values of resistors R5 and R6 are equal to R, the collector potential of transistor Q19 is approximately equal to the voltage value of voltage source VCC, and the collector potential of transistor Q20 is a potential lower than voltage source VCC by R1·1. Furthermore, when the transistor Ql is on and the transistor Q2 is off, I s+=10+1o', I52=0
Similarly, l1l-I13 ■1□-〇, the collector potential of transistor Q19 becomes a potential lower than voltage source VCC by Rt'lt,
The collector potential of transistor Q20 has a voltage value approximately equal to voltage source VCC.

Therefore, transistor Q19. The amplitude ΔV of the oscillation signal taken out from the collector of Q20 is expressed by the following equation.

ΔV=R,・■1 ・・・・・・・・・・・・(8) Substituting the above equation (8) into the equation (6>), the oscillation frequency f is 1°f= ・・・・・・・・・
・(9)4 C-R,・I.

The current I is used to change the oscillation frequency f. Even if the oscillation amplitude ΔV is changed, the oscillation amplitude ΔV does not change, so there is no deterioration in the linearity of the oscillation characteristics. Also, the amplitude ΔV is the resistance R5, R6
It is determined by the resistance value of oscillation signal a and the current value of current source A3, and the amplitude limitation using a diode as in the conventional circuit can be eliminated, thereby preventing waveform rounding as shown in Figure 8 at the rising edge of oscillation signal a. 4 and no second harmonics are generated.

Figure 3 shows the V T using the voltage controlled oscillator shown in Figure 1.
It is a circuit diagram showing an example of an FM modulator of R,
3 is a human power conversion circuit, 4 is an amplifier circuit, 5゜6 is an input terminal,
7 is an inverter, 8 is an output terminal, 9 is the voltage controlled oscillator shown in FIG. 1, Q21-Q34, Q40-Q49 are transistors, R11-R31 are resistors, A4. A5 is a current source, and the parts corresponding to those in FIG. 1 are given the same reference numerals and redundant explanation will be omitted.

In the same figure, the input conversion circuit 3 has a conventional low frequency F
The oscillation frequency of the voltage controlled oscillator 9 is switched and controlled in accordance with two types of methods: an M modulation method and a new method of FM modulation at a higher frequency.

The amplifier circuit 4 amplifies the oscillation signal output from the voltage controlled oscillator 9. A luminance signal is input from the input terminal 5, and a method selection signal for switching the frequency band to be FM modulated is input from the input terminal 6. The luminance signal input from the input terminal 5 is converted into a signal current by the resistors R14 and R15. When the method selection signal manually inputted from the input terminal 65 is at a high level, a command is given to perform FM modulation using the new method at a high frequency.

At this time, transistor Q28 is turned off and transistor Q29 is turned on. This causes transistor 62
6 is on, transistor Q27 is off, and resistor R1
The luminance signal converted into a signal current by 4 is transmitted to the transistor Q26 and the transistor Q3 forming a current mirror.
0. Q31, and a transistor Q33 .Q31 constituting the next current mirror. Q34. Q5. The signal is supplied to the voltage controlled oscillator 9 via Q16 and subjected to FM modulation.

When performing FM modulation at a conventional low frequency, input terminal 6
The method selection signal from is at a low level, turning on transistor Q2B and turning off transistor Q29. This turns on transistor Q27, and the signal current through resistor R15 flows through transistor Q27. Q30. Q31.
Q33. It is supplied to the voltage controlled oscillator 9 via Q34.

Here, by adjusting the resistance values of resistors R14 and R15 to appropriate values, the FM modulation depth can be controlled for each method.Also, by adjusting the resistors R16R17, the FM modulation degree can be controlled independently from input terminal 5. The oscillation frequency when there is no input signal can be controlled.

The amplifier circuit 4 amplifies the FM-modulated luminance signal to an amplitude suitable for recording on the magnetic tape. (2) At 1°R, the voltage value of the circuit power supply VCC is as low as about 5V, so the FM luminance signal cannot be directly extracted from the voltage controlled oscillator 9 with a large amplitude. For this purpose, the amplifier circuit 4 is required. At this time, transistor Q43. Q44 and resistor R26
, R27. By making the input dynamic range of the differential pair larger than the amplitude of the supplied oscillation signal and performing linear operation, the oscillation signal whose second harmonic generation is suppressed is degraded. Instead, it can be amplified and extracted.

In addition, in the voltage controlled oscillator 9, the transistor Q19
．． The resistor R19°R20 connected to the base of Q20 has the effect of preventing circuit parasitic oscillation and suppressing ringing that occurs in the oscillation output waveform. Furthermore, transistor Q17. The base of Q18 is connected to the voltage source V in FIG.
, but in this specific example, the voltage source VCC
It is connected to the. However, the effect is the same as in the case of FIG.

FIG. 4 is a circuit diagram showing another embodiment of the voltage controlled oscillator according to the present invention, Q51. Q52 is a transistor that operates as a switch, R51 to R54 are resistors, and 10 is an input terminal. Portions corresponding to those in FIG. 1 are given the same reference numerals and redundant explanations will be omitted.

In the figure, the collector of transistor Q1 is connected to resistor R5.
3 to the voltage source VCC, and is also connected to the voltage source VCC via a resistor R52 and a transistor Q52. The collector of transistor Q2 is resistor R
54 to the voltage source VCC, and is also connected to the voltage source VCC via a resistor R51 and a transistor Q51.

Transistor Q52. The bases of Q51 are both connected to input terminal 9, and operate as a switch circuit that is controlled on/off by a control signal inputted from input terminal 9.

Next, the operation of this embodiment will be explained.

Current ■ to increase the oscillation frequency f. When increasing transistor Q1. The oscillation amplitude generated at the collector of Q2 also increases, and when the current 1o is further increased, the transistors Ql and Q2 become saturated.

Therefore, the current I. When oscillating at a high frequency by increasing Q51, the transistor Q51. Q52 is turned on, and the load resistance of the collector of the transistor Ql is changed to the resistance R.
53 to resistor R52°R53, and the load resistance of the collector of transistor Q2 to resistor R54 to resistor R51°R54 in parallel to reduce the resistance value of each load resistor. This causes transistor Q1. Q
2 can be prevented from becoming saturated.

Also, when oscillating at a low frequency, transistor Q51. By turning off transistors Q52, 9 transistors Q1. The load resistance of the collector of Q2 is R
53, R54. Therefore, this embodiment can be applied to a VTR.
When used as an FM modulator, a wide range of oscillation operation can be achieved by inputting a method selection signal from the input terminal 9 that selects FM modulation at a low frequency using the conventional method or FM modulation at a high frequency using the new method. I can make you do it.

〔Effect of the invention〕

As explained above, according to the present invention, there is provided a second current source linked to a first current source that charges and discharges a capacitor, a first switch circuit that switches between the first current source, and a second current source that switches the first current source. By providing a second switch circuit that operates in phase, even if the timing of switching the first current source is delayed,
During the delay period, the second current source charges and discharges the capacitor instead, which has the effect of preventing deterioration of linearity of oscillation characteristics due to delay in switching timing, and makes it possible to provide a voltage controlled oscillator with a wide frequency variation range. can.

[Brief explanation of drawings]

0 Fig. 1 is a circuit diagram showing an embodiment of a voltage controlled oscillator according to the present invention, Fig. 2 is a waveform diagram showing signals at each part of Fig. 1, and Fig. 3 is a diagram of an FM modulator using this embodiment. 4 is a circuit diagram showing another embodiment of the voltage controlled '611 oscillator according to the present invention, FIG. 5 is a circuit diagram showing an example of a conventional electric single control oscillator, Figure 7 shows the oscillation characteristics of this conventional voltage controlled oscillator, Figure 7 is a waveform diagram showing the signals of each part in Figure 5, and Figure 8 shows an example of the output waveform of the voltage controlled oscillator shown in Figure 5. FIG. Ql, Q2... I. Landzisk, Q3, which constitutes an astable multihull break. Q4...
...Transistor that constitutes the first switch circuit, Q
5...Transistor forming the first current source, Q14Q15...Transistor forming the second switch circuit, Ql6...
・1-run transistor, CI... constituting the second current source
・・・・・・Capacitor. Representative person B1 land ++ &: SjJ + next part (1 other person) 5th Figure 113- Figure Au4 Yoshichi voltage

Claims (1)

[Claims] 1. A first transistor, a second transistor, a capacitor connected between the emitters of the first transistor and the second transistor, and a current whose magnitude changes depending on an input signal voltage. 1st
A voltage controlled oscillator comprising: a current source; and a first switch circuit that alternately selects and connects the emitters of the first and second transistors to the first current source, the first current source a second current source that generates a current whose magnitude changes in conjunction with the second current source; and a second switch circuit that alternately selects the first and second emitters and connects them to the second current source. and the second current source is connected to the emitter of the second transistor when the first current source is connected to the emitter of the first transistor, and the first current source is connected to the emitter of the second transistor. such that when the second current source is connected to the emitter of the first transistor, the second current source is connected to the emitter of the first transistor;
A voltage controlled oscillator characterized in that the second switch circuit operates synchronously. 2. In claim 1, a third transistor having a base connected to the collector of the first transistor, an emitter connected to the emitter of the third transistor, and a base connected to the collector of the second transistor. a fourth transistor, a first oscillation signal obtained at the collector of the third transistor is supplied to the base of the first transistor, and a second oscillation signal obtained at the collector of the fourth transistor is provided. An oscillation signal is supplied to the base of the second transistor, and the first and second oscillation signals cause the first and second
A voltage controlled oscillator characterized by controlling the operation timing of a switch circuit. 3. Claim 1 or 2, wherein a first resistor is connected to the collector of the first transistor and serves as a first load resistor; and a first resistor is connected to the collector of the second transistor and serves as a second load resistor. The present invention is characterized by comprising: a second resistor, a first means for changing the resistance value of the first load resistor, and a second means for changing the resistance value of the second load resistor. Voltage controlled oscillator. 4. In claim 3, the first means includes a third resistor and a fifth transistor connected in series, which is controlled to turn on and off by a control signal, and the second means comprises a fourth transistor connected in series. and a sixth transistor which is controlled on and off by the control signal are connected in series, the first means being connected to the first resistor, and the second means being connected to the second transistor. A voltage controlled oscillator characterized in that the voltage controlled oscillator is connected in parallel to the means.