JPH02274005A - Microwave voltage controlled oscillator - Google Patents

Abstract

PURPOSE:To eliminate the discontinuity in a relation of a varactor diode bias voltage and an oscillation frequency by executing a termination by a resistance and a capacitor so as not to have a reactance component except the oscillation frequency. CONSTITUTION:To a microstrip line 2 in which the other end is terminated by a resistance 1, a gate terminal of an FET 3 whose drain is grounded is connected, and a dielectric resonator 4 is brought to magnetic field coupling to the microstrip line 2. Also, a double opened microstrip line 6 to which a varactor diode 5 is loaded is brought to magnetic field coupling to the dielectric resonator 4, a bias voltage is supplied from a bias voltage supply terminal 7 and a low-pass filter is constituted of a high impedance line 8 whose tip is short-circuited of 1/4 wavelength by an oscillation frequency, and a low impedance line 9 whose tip is opened of 1/4 wavelength by the oscillation frequency. In this state, by executing a termination by a resistance 11 and a capacitor 12 at a short circuit point of the high impedance line 8, and varying the capacity of the varactor diode 5, the oscillation frequency is varied. In such a way, no discontinuity is generated in a relation of the varactor bias voltage and the oscillation frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a microwave voltage controlled oscillator using a dielectric resonator.

2. Description of the Related Art An example of a conventional microwave voltage controlled oscillator is shown in FIG.

A drain and a gate terminal of a grounded FET 3 are connected to a microstrip line 2 whose other end is terminated with a resistor 1, and a dielectric resonator 4 is magnetically coupled to the microstrip line 2.
After stabilizing the frequency, a C microstrip line 6 with both ends open and equipped with a varactor diode 6 is magnetically coupled to the dielectric resonator 4, and a bias voltage is applied from the bias voltage supply terminal 7 at the oscillation frequency to detect a short circuit at the tip of the dead wavelength. - In addition to the varactor diode 6, the oscillation frequency is changed by changing the capacitance of the varactor diode 5 through a low-pass filter composed of an impedance line 8 and a low impedance line 9 with an open end of 1/4 wavelength at the oscillation frequency. The oscillation output was taken out from the oscillation output terminal 10.

Problems to be Solved by the Invention In such a conventional configuration, a low-pass filter is connected to a low-impedance line 8 that has a member wavelength at the oscillation frequency.
．． 9, the impedance of the A side will not be shorted at frequencies other than the oscillation frequency, and will have a reactance component. Therefore, the circuit becomes a circuit in which a reactance component is connected to the high-impedance line 8, and an unnecessary reactance component is added to the strip line with both ends open, causing unnecessary resonance. As a result, the relationship between the varactor diode bias voltage and the oscillation frequency However, there was a problem in that a discontinuity as shown in FIG. 5 occurred.

The present invention solves these problems, and in the relationship between varactor diode bias voltage and oscillation frequency,
The purpose is to create a microwave voltage controlled oscillator that does not cause discontinuities.

Means for Solving the Problem In order to solve this problem, the present invention uses a low-pass filter for applying a bias voltage to the varactor diode, and a short-circuited high-impedance line at the end of the A wavelength at the oscillation frequency, and a short-circuited high impedance line at the end of the A wavelength at the oscillation frequency. It is a microwave voltage controlled oscillator constructed with an open U-impedance line and terminated with a resistor and a capacitor at the short-circuit point of the high-impedance line with 1/4 wavelength at the oscillation frequency so as not to have a reactance component at frequencies other than the oscillation frequency. It is something.

Operation: This configuration provides a microwave voltage controlled oscillator that does not cause discontinuity in the relationship between the varactor diode bias voltage and the oscillation frequency.

Example Embodiments of the present invention are shown in FIGS. 1 and 2.

This embodiment is a 13Gl-12 microwave voltage controlled oscillator, and is constructed on a Teflon substrate with a thickness of 0.8 mm. That is, the gate terminal of the FET 3 whose drain is grounded is connected to the microstrip line 2 whose other end is terminated with a resistor (SOΩ) 1, and the dielectric resonator 4 is magnetically coupled to the microstrip line 2 to stabilize the frequency. A microstrip line 6 loaded with a varactor diode 5 and open at both ends is magnetically coupled to the dielectric resonator 4, and a bias voltage is applied from the bias voltage supply terminal 7 to a high impedance line with a short-circuited end of 1/4 wavelength at the oscillation frequency [impedance = 120Ω, length = 4.1mm) A low-impedance line of 60Ω with the tip open at the oscillation frequency and the A wavelength [impedance = 50Ω, length = 3.8mm] 9 constitutes a low-pass filter. The impedance line 8 is terminated at the short-circuit point with a resistor [50Ω] 11 and a capacitor 12, and is passed through this low-pass filter to the varactor diode 5, and by changing the capacitance of the varactor diode 6, the oscillation frequency is changed, and the oscillation output is The configuration is such that it is taken out from the oscillation output terminal 10.

FIG. 2 shows the relationship between varactor diode bias voltage and oscillation frequency. Here, when a phase-locked loop is constructed using this microwave voltage controlled oscillator, the capacitance value of the capacitor 12 needs to be high impedance in the loop band and low impedance in the microwave band. Therefore, in this embodiment, it is set to 59F.

According to this embodiment, since the high impedance line 8 is terminated at the short-circuit point with a resistor [60Ω] 11 and a capacitor 12, there is no reactance component on the A side, so it is unnecessary for the microstrip line 6 with both ends open. Since no actance component is added, unnecessary resonance does not occur. Therefore, as shown in FIG. 3, no discontinuity occurs in the relationship between the varactor bias voltage and the oscillation frequency.

Effects of the Invention With the above configuration, it is possible to obtain a microwave voltage controlled oscillator with excellent characteristics in which no discontinuity occurs in the relationship between the varactor bias voltage and the oscillation frequency.

[Brief Description of the Drawings] Figures 1 and 2 are schematic configuration diagrams showing one embodiment of the present invention;
Figure 3 is a relationship diagram showing the relationship between the varactor diode bias voltage and oscillation frequency of this embodiment, Figure 4 is a schematic configuration diagram showing the conventional example, and Figure 6 is the relationship between the varactor diode bias voltage and oscillation frequency of the conventional example. FIG. 1... Resistor, 2... Microstrip line, 3... FET, 4... Dielectric resonator, 5... Paraphthalmology Iode, 6...
...Microstrip line with both ends open, 7...
・Bias supply terminal, 8...High impedance line with 1/4 wavelength at oscillation frequency, 9...Low impedance line with A wavelength at oscillation frequency, 1o...Oscillation output terminal, 11... River: Resistor, 12: Capacitor. Name of agent: Patent attorney Shigetaka Awano

Claims (1)

[Claims] The oscillation frequency is stabilized using a dielectric resonator, and a microstrip line with open ends equipped with a varactor diode is magnetically coupled to the dielectric resonator, so that the oscillation frequency is 1.
Applying a bias voltage to the varactor diode through a low-pass filter composed of a high impedance line with a short-circuited end of a /4 wavelength and a low impedance line with an open end of a 1/4 wavelength at an oscillation frequency, and changing the capacitance of the varactor diode. 1. A microwave voltage controlled oscillator that changes an oscillation frequency by changing the oscillation frequency, characterized in that a short-circuited surface of the high impedance line is terminated with a resistor and a capacitor.