JP2001237642A - Voltage controlled oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a voltage controlled oscillator which oscillates at a frequency equal to or higher than 3 GHz and capable of providing frequency sensitivity equal to or higher than 150 MHz/V. SOLUTION: The cathodes of a varicap diodes 23 and 24 are mutually connected, the mutually connected cathodes are connected to a voltage control terminal 34 through a choke coil 21, the voltage control terminal 34 is grounded through a capacitor 20, an inductor 22 is connected to the anode of the varicap diode 23 and the other terminal is grounded, a choke coil 25 is connected to the anode of the diode 24 and the other terminal is grounded, and further the anode of the diode 24 is connected to the base of a transistor for oscillation through a capacitor 26. Thus, oscillation at a frequency equal to or higher than 3 GHz is realized and a frequency sensitivity equal to or higher than 150 MHz/V can be provided.

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 a mobile communication device such as an automobile telephone or a portable telephone.

[0002]

2. Description of the Related Art A conventional voltage controlled oscillator will be described below. In the conventional voltage controlled oscillator, as shown in FIG. 4, the voltage control terminal 16 is connected to the cathode of the varicap diode 3 via the choke coil 2, the anode of the varicap diode 3 is grounded, and The cathode is connected to the capacitor 4, the other end is connected to the inductor 5 and the capacitor 6, the other end of the inductor 5 is grounded, the other end of the capacitor 6 is connected to the base of the transistor 10, and the power terminal 17 is connected to the resistor 7 The resistor 8 is connected between the base and the ground of the transistor 10, the capacitor 9 is connected between the base and the emitter of the transistor 10, and the collector of the transistor 10 is connected to the power supply terminal 17 and the capacitor 13. Connected, the other end of the capacitor 13 is grounded, The capacitor 12 is connected in parallel between the emitter of the transistor 10 and the ground, the capacitor 14 is connected to the emitter of the transistor 10, the other end is input to the buffer amplifier 15, and the output of the buffer amplifier 15 is connected to the output terminal 18. Was. The oscillation frequency was about 3 GHz or less, and the frequency sensitivity was about 150 MHz / V or less.

[0003]

However, in such a conventional configuration, the upper limit of the oscillation frequency is from 2 GHz to at most 3 GHz, and the frequency sensitivity is limited to about 150 MHz / V. Could not get. This is because there is no varicap having a small capacitance and a large variation width.

An object of the present invention is to solve such a problem and to provide a voltage controlled oscillator capable of obtaining an oscillation frequency of 3 GHz or more and a high frequency sensitivity of 150 MHz / V or more. is there.

[0005]

In order to achieve this object, a voltage controlled oscillator according to the present invention comprises a first varicap diode formed of a chip component and a second varicap diode formed of a chip component. The cathodes are connected to each other, and the mutually connected cathodes are connected to a voltage control terminal via a choke coil, and the voltage control terminal is grounded via a first capacitor, and is connected to an anode of the first varicap diode. An inductor is connected and the other end is grounded, a choke coil is connected to the anode of the second varicap diode and the other end is grounded, and the anode of the second varicap diode is connected via a second capacitor. It is connected to an oscillation transistor. As a result, the oscillation frequency of 3 GHz or more and 1
High frequency sensitivity of 50 MHz / V or more can be obtained.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to a first aspect of the present invention, a cathode of a first varicap diode formed of a chip component and a cathode of a second varicap diode formed of a chip component are connected to each other. The cathodes connected to each other are connected to a voltage control terminal via a choke coil, the voltage control terminal is grounded via a first capacitor, and an inductor is connected to the anode of the first varicap diode. One end is grounded, a choke coil is connected to the anode of the second varicap diode, and the other end is grounded. The anode of the second varicap diode is connected to an oscillation transistor via a second capacitor. This is a voltage controlled oscillator that has been integrated without deteriorating the capacitance change ratio by connecting varicap diodes in series. 3GHz by reducing the capacity
The above oscillation frequency and high frequency sensitivity of 150 MHz / V or more can be obtained.

According to a second aspect of the present invention, the other end of the resistor connected to the emitter of the oscillation transistor is connected to the middle of an inductor connected to the anode of the first varicap diode. This is a voltage-controlled oscillator, in which an inductor component is added in series to the emitter resistor, so that output power and C / N can be improved.

According to a third aspect of the present invention, a part or all of the inductor to which the anode of the first varicap diode is connected is formed of a strip line, and the frequency can be adjusted by trimming a part of the strip line. The trimming of a part of the strip line changes the inductance of the strip line, so that the frequency can be adjusted.

According to the present invention, a part or all of the choke coil connected to the anode of the second varicap diode is constituted by a strip line, and the frequency can be adjusted by trimming a part thereof. The trimming of a part of the strip line changes the inductance of the strip line, so that the frequency can be adjusted.

The voltage controlled oscillator according to claim 5 is the voltage controlled oscillator according to claim 1, wherein an output from the oscillating unit is connected to the buffer amplifier unit via two or more capacitors connected in series. Since the combined capacitance can be reduced by using two or more series capacitors and the variation can be suppressed, the fluctuation of the oscillation frequency due to the fluctuation of the load can be reduced.

The invention according to claim 6 is the voltage controlled oscillator according to claim 1, wherein the resonance circuit section and the oscillation circuit section are connected by two or more capacitors connected in series. Since the combined capacitance can be reduced and the variation can be suppressed, the initial variation of the oscillation frequency can be suppressed.

Embodiment 1 Hereinafter, the present invention will be described with reference to the drawings. FIG. 1 shows a circuit diagram of a voltage-controlled oscillation circuit according to Embodiment 1 of the present invention. In the first embodiment, the cathodes of the first varicap diode 23 and the second varicap diode 24 are connected to each other.
Is connected to the voltage control terminal 34 via the
4 is grounded via a first capacitor 20, and an inductor 22 is connected to the anode of a first varicap diode 23.
And the other end is grounded, and a choke coil 25 is connected to the anode of the second varicap diode 24,
The other end is grounded, and the second capacitor 26 is connected to the anode of the second varicap diode 24. The other end of the capacitor 26 is connected to the base of the transistor 31 of the oscillation circuit block 38. Oscillation circuit block 38
Connects the collector of the transistor 31 to the power supply terminal 35, connects the resistor 29 to the power supply terminal 35, and connects the other end to the base of the transistor 31;
Is connected between the base and the ground of the transistor 31, the capacitor 28 is connected between the base and the emitter of the transistor 31, and the resistor 30 and the capacitor 32 are connected to the transistor 31
Is connected in parallel between the emitter of the
Is connected between the power terminal 35 and the ground, and the output terminal 36
Is a configuration connected to the emitter of the transistor 31. Here, the oscillator circuit block 38 is of the common collector type, but may be of the common base type. Further, the output terminal 36 is connected to a capacitor 39, the other end is connected to a capacitor 40, and the other end of the capacitor 40 is connected to a buffer amplifier 41. The output of the buffer amplifier 41 is output to an output terminal 42. 37a is a resonance circuit block.

The varicap diodes, resistors, capacitors, and transistors used here all use surface mount components (chip components).

As described above, according to the first embodiment, the combined capacitance can be reduced without deteriorating the capacitance change ratio by connecting the varicap diodes 23 and 24 in series, so that the oscillation frequency of 3 GHz or more and the oscillation frequency of 150 MHz / V or more High frequency sensitivity can be obtained. Further, the buffer amplifier 4 is connected by two capacitors 39 and 40 connected in series.
1, it is possible to suppress characteristic deterioration due to load fluctuation.

(Embodiment 2) FIG. 2 is a circuit diagram showing a part of a resonance circuit block 37b and an oscillation circuit block 38 in Embodiment 2. In the second embodiment, the cathodes of the first varicap diode 23 and the second varicap diode 24 are connected to each other, and the connected cathodes are connected to the voltage control terminal 34 via the choke coil 21.
And the voltage control terminal 34 is connected to the first capacitor 20.
And a first varicap diode 23
Is connected to a strip line 51 formed on the substrate, the end of the strip line 51 is grounded, the inductor 52 is connected to the anode of the second varicap diode 24, and the other end is a choke coil 53.
The other end of the choke coil 53 is connected to one end of a strip line 54 formed on the substrate, the end of the strip line 54 is grounded, and the capacitor 26 is connected to a connection point between the inductor 52 and the choke coil 53,
The other end of the capacitor 26 is connected to the base of the transistor 31 of the oscillation circuit block 38, and the other end of the resistor 30 connected to the emitter of the oscillation transistor 31 included in the oscillation circuit block 38 is connected to a part of the strip line 51. It is connected. Note that the inductor 52 and the choke coil 53 may be replaced by a strip line formed on the substrate, and the capacitor 26 may be connected to a part of the inductor 52 formed by the strip line.

As described above, according to the second embodiment, the oscillation frequency of 3 GHz or more and the 15
High frequency sensitivity of 0 MHz / V or more can be obtained,
Further, a strip line 51, a strip line 52,
The frequency can be adjusted by trimming a part of the strip lines 53 and 54.

(Embodiment 3) FIG. 3 is a circuit diagram showing a part of a resonance circuit block 37c and an oscillation circuit block 38 in Embodiment 3. In the third embodiment, the cathodes of the first varicap diode 23 and the second varicap diode 24 are connected to each other, and the connected cathodes are connected to the voltage control terminal 34 via the choke coil 21.
And the voltage control terminal 34 is connected to the first capacitor 20.
And a first varicap diode 23
Is connected to a strip line 51 formed on the substrate, the end of the strip line 51 is grounded, the anode of the second varicap diode 24 is connected to the strip line 55 formed on the substrate, and the other end is connected. The other end of the choke coil 53 is connected to a strip line 54 formed on a substrate, the other end of the strip line 54 is grounded, and one end of the capacitor 26 is connected to a part of the strip line 55. And the other end is connected to the capacitor 56, and the other end of the capacitor 56 is connected to the transistor 31 of the oscillation circuit section 38.
And a resistor 30 connected to the emitter of the oscillation transistor 31 included in the oscillation circuit block 38.
Is connected to the ground-side terminal of the strip line 51.

As described above, according to the third embodiment, an oscillation frequency of 3 GHz or more and
High frequency sensitivity of 0 MHz / V or more can be obtained. Furthermore, strip line 51, strip line 5
The frequency can be adjusted by trimming the part 4 and a part of the strip line 55. Further, the capacitor 5 in which the resonance circuit 37c and the oscillation circuit 38 are connected in series
By connecting at 6, 26, the initial frequency variation can be reduced.

[0019]

As described above, according to the present invention, the cathodes of the first varicap diode formed of the chip component and the second varicap diode formed of the chip component are connected to each other and connected to each other. The connected cathode is connected to a voltage control terminal via a choke coil, the voltage control terminal is grounded via a first capacitor, an inductor is connected to the anode of the first varicap diode, and the other end is grounded. A choke coil is connected to the anode of the second varicap diode, and the other end is grounded. The anode of the second varicap diode is connected to a voltage connected to the oscillation transistor via a second capacitor. A controlled oscillator that reduces the combined capacitance without deteriorating the capacitance change ratio by connecting varicaps in series. It is intended to obtain a high frequency sensitivity of the above oscillation frequency and 150 MHz / V above 3GHz by.

[Brief description of the drawings]

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

FIG. 2 is a main part circuit diagram of a voltage controlled oscillator according to a second embodiment of the present invention;

FIG. 3 is a main part circuit diagram of a voltage controlled oscillator according to a third embodiment of the present invention;

FIG. 4 is a circuit diagram of a conventional voltage controlled oscillator.

[Explanation of symbols]

 Reference Signs List 20 capacitor 21 choke coil 22 inductor 23 varicap diode 24 varicap diode 25 choke coil 26 capacitor 31 transistor 34 voltage control terminal 35 power supply terminal 36 output terminal 37a resonance circuit block 38 oscillation circuit block

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kouji Hashimoto 1006 Kazuma Kadoma, Kazuma, Osaka Prefecture F-term in Matsushita Electric Industrial Co., Ltd. KK02 KK09 KK22 KK25 LL04 MM01

Claims (6)

[Claims] 1. A cathode of a first varicap diode formed of a chip component and a cathode of a second varicap diode formed of a chip component are connected to each other, and the connected cathodes are connected to each other via a choke coil. The voltage control terminal is connected to a ground through a first capacitor, an inductor is connected to the anode of the first varicap diode, and the other end is grounded, and the voltage control terminal is connected to the second varicap diode. A voltage controlled oscillator, wherein a choke coil is connected to an anode and the other end is grounded, and an anode of the second varicap diode is connected to an oscillation transistor via a second capacitor. 2. The voltage-controlled oscillator according to claim 1, wherein the other end of the resistor connected to the emitter of the oscillation transistor is connected to the middle of an inductor connected to the anode of the first varicap diode. 3. The voltage according to claim 1, wherein a part or all of the inductor to which the anode of the first varicap diode is connected is constituted by a strip line, and the frequency can be adjusted by trimming a part of the strip line. Controlled oscillator. 4. The method according to claim 1, wherein a part or all of the choke coil connected to the anode of the second varicap diode is constituted by a strip line, and the frequency can be adjusted by trimming a part thereof. Voltage controlled oscillator. 5. An output from an oscillating unit connected in series to two
2. The voltage controlled oscillator according to claim 1, wherein the voltage controlled oscillator is connected to the buffer amplifier section via one or more capacitors. 6. The voltage controlled oscillator according to claim 1, wherein the resonance circuit and the oscillation circuit are connected by two or more capacitors connected in series.