JPS5873221A - Oscillator - Google Patents

Abstract

PURPOSE:To simplify the circuit constitution and to reduce the cost, by controlling the depth of modulation independently of the center frequency. CONSTITUTION:When an output of a flip-flop 6 is denoted as 1, a switch 3 is connected to the position (a), and a capacitor C is charged with a current source 1. Inversely, the output of the circuit 6 is denoted as 0, the switch 3 is connected to the position (b) and the charge in the capacitor C is discharged to a current source 2. When a potential VOSC of the capacitor C is higher than a reference voltage Vu of a comparator 5, the output of the comparator goes to 1 to reset the circuit 6 and the output goes to 0. Inversely, when the potential VOSC is lower than a reference potential Vl of a comparator 4, the output of the circuit 6 goes to 1. Thus, the oscillating frequency (output of the circuit 6) can be controlled with currents i1 and i2. Further, the depth of modulation can be controlled with the voltages Vu and Vl.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an oscillator, particularly a voltage frill-stretched oscillator (VCO) whose oscillation frequency varies depending on the input voltage. It is possible to control the frequency fo independently, so that the multiplier (or L
OG (g circuit, Anti-LOG l!ll!1 road,
This eliminates the need for filters (e.g., filters, etc.), reduces the circuit configuration and reduces costs.

Conventional voltage 7m1m oscillator (Voltage Cont
In the oscillator controlled by the oscillator, the center oscillation frequency fo % F' MR frequency deviation is as follows. In order to change the oscillation frequency from fo to fo+Δf? 111]' from Vc to (1+If/fo
) It is necessary to set it to Vc. That is, in the conventional VOC, when the human control voltage Vc is changed to change the center oscillation frequency fo, the modulation depth d=jf/f.

If you try to keep it constant, what is the manual system?1f41. Pressure Vc'
f: had to be multiplied by (1+Δf/fo) and required a button μ circuit, resulting in a double-isolated circuit configuration and high cost.

The present invention was made in view of the above-mentioned circumstances, and
In particular, the modulation depth d=Δf/f, o can be controlled independently of the center oscillation frequency IXfo, thereby eliminating the need for a multiplier (or LOG circuit, Anti-LOG circuit, power-on device, etc.), This is intended to simplify the circuit configuration and reduce the cost.

The figure is an electric circuit diagram for explaining one embodiment of the present invention. In the figure, 1 is a first current source, 2 is a second current W13 is a switch, 4 is a first comparator, and 5 is a first current source. Comparator 2 and 6 are flip-flop circuits. Now, if the output signal of the flip-flop circuit 6 is "1", the switch 3 is connected to the a side, and the capacitor C is turned on by the current 11 of the current source 1. Conversely, when the output signal of the flip-flop circuit 6 is "0", the switch 3 is connected to the b side, and the charge of the capacitor C is equal to the current 1 of the current source 2.
2 and is discharged. Now, if the output signal of the flip-flop circuit 6 is ``1'' (or ``0''), the potential Vosc of the capacitor C increases (or decreases).
Then, when Vase becomes higher than the reference Vu of the comparator 5 (or the diagnostic pressure Vl of the comparator 4
), the output signal of the comparator 4 (or 5) becomes ``1'' (or ``0''), which resets (or cents) the flip-flop circuit 6, causing the output signal of the flip-flop circuit to become ``0''. (or ゝゝ1“). Note that in the above, Vu>Vi.

Next, the oscillation frequency, that is, the output signal of the flip-flop circuit 6 will be explained.

First, the output signal of the flip-flop circuit 6 changes from the 0" state to the "1 // state, and then the "0" state! Assuming that the total time t1 is required until the system becomes active, it is expressed as its t1=C(Vu −Vl) 1 .

Similarly, the output circuit of the flip-flop circuit 6 is 1
If the time from the “state” to the “0” state and then to the “1” state is +2, then i2* +2
=C(Vu-Vl)2.

Therefore, the frequency f of the output signal of the flip-flop circuit 6
becomes .

Now, for simplicity, let i = i, = , +2.

As is clear from equation (5), the frequency fFi is 0 compared to the current i (f=β1, but β=1/2C(V
u-Vl)), the frequency f by controlling the amount of current
can be controlled.

Now, if we consider the simplest case of changing the oscillation frequency f to (1+d)f, the oscillation frequency f gold, f=β11 the depth of the tone d
If d-Δf/f, then (1+d)f2β((1+
a) il ・ ((also). Therefore, in the conventional technology, in order to change the oscillation frequency from f to (1+d)f, it is necessary to multiply ′tunura,i by ・(]10d) That is, in order to significantly change the center frequency fo2βto and keep the modulation depth d constant, it was necessary to apply (1+d) human power to .'/+In Yuanming, Vu and/or Vl> are used to control this d, and f-β1=l(1+d
) βli −Ri.

Now, for the sake of simplicity, if we set V=Vu=-Vl>IJ, then f'=--18) CV, and from equation (8), we can obtain.

Here, 1dl (1 and this are Therefore, the above formula (9) is i (1+d) f dimension □...01> 4cJ(x-d)Vl becomes.

Therefore, regardless of the value of the center oscillation frequency f, the modulation depth d-Δf/f of the -stroke can be met.

In addition, one embodiment of the present invention has been described above, and /C is
The present invention is not limited to the above-mentioned embodiment, for example, it is possible to simplify one of the current sources 1 or 2 to a simple grounding circuit, and it is also possible to simplify the current source 1 or 2 to a simple ground circuit. It is possible to simplify the circuit configuration to 6U, one comparator and a mono-multivibrator, and in the past, it has been digitized by replacing capacitor C with an accumulator resistor and current sources 1 and 2 with constant generators. As is clear from the above explanation, according to the present invention, the center oscillation frequency fo can be significantly changed while the modulation depth d - Δf/fo is set to an arbitrary constant value. 0 which can provide an oscillator capable of

[Brief explanation of drawings]

The figure is a detailed circuit diagram illustrating an embodiment of the present invention. 1.2...' Current source, 3. Switch, 4. Comparator, 6. Flip-flop circuit.

Claims (1)

[Claims] - a female source, a capacitor, a switch for connecting between the current source and the capacitor to charge and discharge the capacitor, and a comparator for comparing the potential of the code capacitor with the output level. , and a flip-flop circuit that is tllJ 141 in response to the output signal of the comparator, and the switch is switched according to the output signal of the flip-flop circuit to charge or discharge the nil capacitor, and the charging voltage is set to a desired level. resetting (or setting) the flip-flop circuit when the voltage rises to
An oscillator whose % rut is to set (or reset) the flip-flop circuit when the discharge voltage drops to a predetermined value.