JPH07245527A - Voltage controlled oscillator - Google Patents

Abstract

PURPOSE:To attain stable oscillation and to reduce the power consumption and the cost by providing a band pass filter comprising a dielectric resonator, an inter-stage capacitor and input/output capacitors to the oscillator and connecting the filter to an oscillating circuit through the input/output capacitors. CONSTITUTION:An oscillating signal of an oscillation circuit comprising an oscillation transistor(TR) 1, resistors R1-R4 for DC bias of the TR 1, a dielectric resonator DR 1, capacitors C1-C4, and a varactor diode D1 is given to a capacitor C5. Then a band pass filter is made up of dielectric resonators DR2, DR3, a capacitor C6 to obtain an inter-stage capacitance, and capacitors C5, C7 to obtain input/output capacitance and connected to the oscillation circuit. That is, the band pass filter passing through only 2 times oscillation frequency component of the fundamental frequency component is connected o an output terminal o the voltage controlled oscillator circuit providing an output of a harmonics of integer multiples of the fundamental component by the nonlinearity of the TR and the fundamental oscillation frequency component.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage controlled oscillator used for communication equipment and the like.

[0002]

2. Description of the Related Art In recent years, voltage controlled oscillators used in information and communication equipment have a wide range of applications, and the frequency band used therefor is from the conventional 0.9 GHz band to 1.9 GHz.
It is shifting to the z band.

A voltage controlled oscillator conventionally used will be described below. FIG. 5 is a circuit diagram showing a conventional voltage controlled oscillator. In FIG. 5, TR2 is an oscillation transistor, R5, R6, R7 and R8 are resistors for direct current bias of the transistor TR2, DR4 is a dielectric resonator, C8, C9, C10 and C11 are capacitors, and D is a capacitor.
Reference numeral 2 is a variable capacitance diode, and an oscillation circuit is formed by the electronic components and the like. A signal produced by this oscillator circuit is output through a low-pass filter composed of a capacitor C13 and an inductance L1 via a coupling capacitor C12 with the outside.

The oscillation frequency is controlled by the voltage by externally applying a voltage between the capacitor C11 and the variable capacitance diode D2. For example, the oscillation frequency control sensitivity in a mobile phone is 13 MHz / V.

Further, a dielectric resonator DR4 is required to form a voltage controlled oscillator circuit, and the voltage controlled oscillator of a portable mobile radio device is a dielectric resonator which can obtain a high Q as a dielectric resonator. Are using.

FIG. 6 is a graph showing characteristics of oscillation frequency-output power of the voltage controlled oscillator shown in FIG. The fundamental oscillation frequency component output from the voltage controlled oscillator is F1, and the oscillation frequency components that are integral multiples of the oscillation frequency component are F2, F3, and F4, respectively. Oscillation frequency components other than F1 adversely affect the amplifier and the like connected to the output terminal of the voltage controlled oscillator, and therefore must be suppressed to the lowest possible level.

[0007]

However, in the above conventional configuration, in order to directly oscillate a high frequency near 2 GHz, a dielectric resonator having a large unloaded Q is used, and the cutoff frequency is 10 GHz or more. And NF
Unless a transistor having a small size is used, the C / N characteristics required for communication devices such as mobile phones cannot be satisfied. Further, it is difficult to secure the stability in the environmental temperature characteristic and the stability due to the fluctuation of the external load, and the abnormal oscillation easily occurs.

An object of the present invention is to provide not only stable oscillation but also low power consumption and low cost voltage controlled oscillator.

[0009]

In order to solve the above problems, the present invention provides an oscillation circuit using a dielectric resonator capable of controlling the oscillation frequency by externally applying a voltage to a variable capacitance diode. In, a bandpass filter consisting of two or more dielectric resonators having a pass band at a frequency twice the fundamental oscillation frequency, an interstage capacitance and an input / output capacitance is formed, and the input / output capacitance of the bandpass filter is It is configured by connecting to the oscillation circuit via the.

[0010]

According to the present invention, with the above configuration, the fundamental oscillation frequency component due to the resonance condition of the voltage controlled oscillation circuit using the dielectric resonator and the harmonic component which is an integral multiple of the fundamental oscillation frequency are output due to the non-linearity of the transistor. To be done. At the output terminal of the voltage controlled oscillation circuit, only the oscillation frequency component twice the fundamental oscillation frequency component corresponds to the pass band of the bandpass filter, so only the double frequency component appears as an output, and the fundamental oscillation frequency component Is attenuated by the bandpass filter. Also, other oscillation frequency components, for example, 3
Double frequency components are also attenuated by the bandpass filter.

[0011]

1 is a circuit diagram of a voltage-controlled oscillator using a bandpass filter composed of two dielectric resonators to cut off a band of a fundamental oscillation frequency, which is an embodiment of the present invention. It demonstrates using.

In FIG. 1, TR1 is a transistor for oscillation, and R1, R2, R3 and R4 are transistor T respectively.
A resistor for DC bias of R1, DR1 is a dielectric resonator,
C1, C2, C3 and C4 are capacitors, D1 is a variable capacitance diode which constitutes an oscillation circuit by the above electronic parts, and the oscillation signal of this oscillation circuit is output to the capacitor C5. DR2 and DR3 are dielectric resonators and C6, respectively.
Are capacitors for obtaining interstage capacitance, C5 and C7 are capacitors for obtaining input / output capacitance, and these electronic components constitute a bandpass filter circuit.

Further, the oscillation frequency is controlled by the voltage by externally applying a voltage to the variable capacitance diode D1, but the frequency control range of the fundamental oscillation wave frequency in the voltage range of 2 to 3 V is 10 MHz / V. Then,
With the double oscillation frequency component, the frequency control range is doubled to 20 MHz / V in the voltage range of 2 to 3 V, but the desired frequency control range can be obtained by appropriately setting the capacitance of the capacitor C4. You can

Next, the operation of the voltage controlled oscillator will be described with reference to FIG.
This will be described with reference to the block diagram of FIG. The oscillation frequency component output from the oscillator circuit 1 is output via the bandpass filter 2. Since the bandpass filter 2 is a bandpass filter having an oscillation frequency component twice the fundamental oscillation frequency component of the oscillation circuit 1 as the bandwidth, only the fundamental oscillation frequency passes, and the other oscillation frequency components pass through the bandpass filter 2. Attenuated by An amplifier and a PLL are connected to the output terminal 3 of the voltage controlled oscillator. Further, a normal PLL is connected to the power supply terminal 4 for the voltage applied to the variable capacitance diode D1, and the voltage is output from the PLL and locked to the target oscillation frequency.

FIG. 3 is a graph showing characteristics of oscillation frequency-output power of the voltage controlled oscillator shown in FIG. The horizontal axis represents the oscillation frequency and the vertical axis represents the output power. The fundamental oscillation frequency component output from the voltage controlled oscillator is F1, and the oscillation frequency components that are integral multiples of the oscillation frequency component are F2, F3, and F4, respectively. The desired oscillation frequency component is F2.

FIG. 4 is a perspective view of a dielectric resonator used in a voltage controlled oscillator according to an embodiment of the present invention. The dielectric resonator 5 has an inner conductor 7 formed on the inner peripheral surface of a coaxial dielectric 6 and an outer conductor 8 formed on the outer peripheral surface thereof, and both conductors are connected at one end of the coaxial. The material of the dielectric 6 is BaO-
A TiO ₂ system, a BaO—TiO ₂ —Re ₂ O ₃ system, or a Zr—Sn—TiO ₄ system is used, and the dielectric constant is 30 to 110.

The inner conductor 7, the outer conductor 8 and the short-circuit surface of the dielectric resonator 5 are electroless copper plated and then electrolytic copper plated, or a conductor electrode is formed by baking silver paste or the like. is doing. It should be noted that both conductor electrodes may be subjected to electrolytic solder plating in order to improve solderability. At this time, the outer shape of the dielectric resonator 5 is rectangular and the inner diameter is circular.

In order to connect the dielectric resonator 5 to an external circuit, the necessary terminal 9 is connected to the end surface opposite to the one connecting the outer conductor 8 and the inner conductor 7 of the dielectric resonator 5. It is further inserted and electrically connected to the inner conductor 7.
The connection method is press fitting, soldering, or fixing with a conductive adhesive.

The material of the terminal 9 is phosphor bronze, the surface of which is plated with electrolytic copper and then nickel, and further soldered to improve solderability. .

Instead of solder plating, platinum treatment may be performed for the purpose of reducing conductor loss.

[0021]

According to the present invention, in a voltage controlled oscillator circuit using a dielectric resonator, the voltage at which a harmonic component which is an integral multiple of the fundamental oscillation frequency is output due to the nonlinearity of the fundamental oscillation frequency component and the transistor. By connecting to the output terminal of the control oscillation circuit a bandpass filter that passes only the oscillation frequency component twice the fundamental oscillation frequency component, it is possible to efficiently and stably take out only the oscillation frequency component twice the frequency. Moreover, the fundamental oscillation frequency component and 3
Since the quadruple and quadruple oscillation frequency components are attenuated by the bandpass filter, abnormal oscillation of the amplifier connected to the output terminal and malfunction of the PLL can be prevented.

Further, since the deterioration of the no-load Q of the resonance circuit can be prevented by setting the capacitance of the capacitor C4 to a small value, the C / N characteristic of the voltage controlled oscillator can be improved and, compared with the conventional case, Cost can be reduced because the used voltage controlled oscillator components can be used.
It can be suppressed to / 2.

Further, the power consumption can be halved as compared with the oscillator using the frequency multiplier.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a voltage controlled oscillator according to an embodiment of the present invention.

FIG. 2 is a block diagram of a voltage controlled oscillator according to an embodiment of the present invention.

FIG. 3 is a graph showing characteristics of oscillation frequency-output power of the voltage controlled oscillator according to the embodiment of the present invention.

FIG. 4 is a perspective view of a dielectric resonator used in a voltage controlled oscillator according to an embodiment of the present invention.

FIG. 5 is a circuit diagram of a conventional voltage controlled oscillator.

FIG. 6 is a graph showing characteristics of oscillation frequency-output power of a conventional voltage controlled oscillator.

[Explanation of symbols]

 R1 to R8 Resistances C1 to C13 Capacitors TR1 to TR3 Transistors D1 and D2 Variable capacitance diodes DR1 to DR4 Dielectric resonator L1 Inductance 1 Oscillation circuit 2 Bandpass filter 3 Output terminal 4 Power supply terminal 5 Dielectric resonator 6 Dielectric 7 Internal Conductor 8 Outer conductor 9 Terminal

Claims (2)

[Claims] 1. An oscillating circuit for controlling an oscillating frequency by applying an applied voltage with a variable capacitance diode, two or more dielectric resonators for passing an oscillating frequency twice as high as a fundamental oscillating frequency, an interstage capacitance and an input capacitor. A voltage-controlled oscillator, comprising: a bandpass filter composed of an output capacitor, wherein the bandpass filter and the oscillation circuit are joined via the input / output capacitor. 2. A voltage controlled oscillator according to claim 1, wherein a dielectric resonator having a rectangular outer shape and a circular inner diameter is used.