JPS5879306A - Oscillating circuit - Google Patents

Abstract

PURPOSE:To make a titled circuit small-sized withot deteriorating the characteristics, by using a distributed constant resonance line and a lumped constant inductor for a resonance circuit and providing a function capable of correcting the frequency shift to the lumped constant section. CONSTITUTION:A resonance circuit is constituted as shown in figure, by patterning a distribution constant resonance circuit 4 and a lumped constant inductor 5. The entire pattern can be made small in size for the resonance circuit through the use of the lumped constant inductor 5, and also the frequncy adjusting function can be gien by soldering and cutting off fine printed lines of the inductor. One end of the resonance circuit is provided with a varactor element 7 via a capacitor 6, a control voltage VF is applied to the element 7 and another end is connected to a collector of a transistor 9 as shown in figure, allowing to form a transistor type Colpitts oscillation circuit having a generic negative resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an oscillation circuit used in a high frequency band. Generally, in circuits used in high frequency bands (VHF, VHF band), strip-type distributed constant lines using low-loss substrates are often used from the viewpoint of economy and usage.

In particular, the main characteristics of oscillator circuits are stability and miniaturization, and noise characteristics are important for voltage-controlled oscillators used in frequency synthesizers, etc. in mobile communications. In the characteristics, the no-load Q of the resonant line occupies an important proportion.

For example, one way to increase the no-load Q of a resonant line is to design the line so that its characteristic impedance is small, but this is contrary to the demand for miniaturization. Furthermore, voltage controlled oscillators used in frequency synthesizers and the like have a main control function determined from the loop gain of the phase synchronization system and a manufacturing process. Two variable capacitance varactors are used to provide an adjustment function to correct frequency deviations due to element variations, and these varactors are generally connected to a resonant line to obtain the required frequency change width, and the varactor itself The series resistor R8 reduces the no-load Q of the resonant line.

Figure 1 shows a conventional shortened resonant circuit, where 1 is an inductor and 2 and 3 are capacitive elements.In voltage controlled oscillators, capacitive elements 2 and 3 are equipped with varactors to make the resonant frequency variable. However, as described above, the size of the oscillator itself becomes large in order to satisfy stability and noise characteristics, and the two varactors deteriorate the no-load Q of the inductor 1.

The present invention adopts a distributed constant resonant line and a lumped constant inductor for the resonant line, and provides an adjustment function in the lumped constant part instead of the adjustment function varactor that corrects frequency deviation, thereby reducing the size without deteriorating the characteristics. The present invention provides an oscillation circuit that can perform the following functions.

An embodiment of the present invention will be described in detail below with reference to the drawings.

Figure 2 shows a resonant circuit used in the oscillation circuit of the present invention, in which a distributed constant resonant line 4 and a lumped constant inductor 6 are patterned, and the lumped constant section is designed to reduce the size of the resonant circuit. Furthermore, by connecting or cutting the thin wires in that part, a frequency adjustment function is provided, and since the frequency adjustment function is provided in the lumped constant part on the zero characteristic, the conventional adjustment varactor can be eliminated. Since the resonant line can be configured with one varactor, the no-load Q of the resonant line is improved, and since this varactor is easily modulated by external noise, by removing it, the line becomes resistant to external noise.

Further, the admittance of the resonant circuit can be increased by including a lumped constant, and the frequency variable range can be widened with respect to the required voltage, which is preferable when used in a frequency synthesizer or the like.

Although there is Q deterioration in the lumped constant inductor section 6, by removing one varactor, the Q deterioration is sufficiently compensated for and, in fact, superiority in noise characteristics can be seen.

FIG. 3 shows an oscillation/oscillation circuit in an embodiment of the present invention using this resonant circuit, which is a general transistor-type Colpic oscillation circuit with negative resistance. A resonant circuit is coupled.

A varactor element 7 is provided at one end of the distributed constant resonant line 4 via a capacitive element 6, and a terminal 8 is connected to the cathode side of the varactor element 7, to which a varactor voltage vF is applied.

FIG. 4 shows the frequency variable range characteristics of an embodiment of the present invention, and FIG. 6 shows a comparison of the noise characteristics with the conventional one. In both characteristics, the superiority of the present invention is recognized.

In addition, regarding the noise characteristics, the detuning frequency is 20 kt (2 to 2 in z).
There is an improvement in adB.

When creating a bend in the resonant line on the fC structure, this 9
At the 0° bend, it becomes capacitive and deteriorates the no-load Q of one path. In the case of the present invention, this drawback can be prevented by installing a lumped constant inductor at this bend, as shown in FIG. 3, for example. Alternatively, when using a dielectric substrate clad with negative-side steel and dividing the resonant line into two on both sides, it is also an effective means to install a lumped constant at the connection part.

As described above, the present invention uses a composite resonant circuit in which the inductor section is realized by a distributed constant line and a lumped constant inductor, thereby achieving miniaturization without deteriorating stability and noise characteristics, and achieving resonance. It is possible to provide an oscillation circuit that has advantages such as being highly flexible in terms of circuit arrangement and configuration, and having an adjustment function in the lumped constant section and being economical.

[Brief explanation of the drawing]

Fig. 1 is a wiring diagram of a conventional shortened four-resonance circuit, Fig. 2 is a wiring diagram of a resonant circuit used in the oscillation circuit of the present invention, Fig. 3 is a wiring diagram of an oscillation circuit in an embodiment of the present invention, and Fig. Figure 6 and Figure 6 are diagrams showing a comparison of the frequency variable range characteristics and sideband noise characteristics of a conventional oscillator circuit and an oscillator of the present invention.・・・－・・・Capacitive element, 6... Lumped constant inductor, 6...
. . . A varactor circuit section having a capacitance value equivalent to the capacitive element 2, 9 . . . Transistor. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 3

Claims (1)

[Scope of Claims] (1) An oscillation circuit comprising a resonant circuit comprising an inductor section and a capacitance section, the inductor section comprising a distributed constant line and a lumped constant inductor. ＠) The oscillation circuit according to claim 1, characterized in that the frequency is adjusted by finely patterning the lumped constant inductor and cutting or shorting that part. G3) The oscillation circuit according to claim 1, wherein the inductor section is configured by connecting a lumped constant inductor and a distributed constant line in series on both sides of the lid. (4) A claim characterized in that the distributed constant lines provided on both sides of the concentrated foot inductor are linear, and the time extension directions of these distributed constant lines form a constant angle. The oscillation circuit according to item 3. (6) Distributed constant lines are provided on both sides of a double-sided steel-clad dielectric substrate, and a lumped constant inductor is used to connect the distributed constant lines on both sides.
The oscillation circuit according to any one of items 1 to 4.