JPH0730328A - Oscillator circuit - Google Patents

Abstract

(57) [Abstract] [Object] An object of the present invention is to provide an oscillator circuit which can obtain good CNR characteristics and can be reduced in circuit scale. [Structure] One end of the carrier signal oscillation stripline 11 is grounded, and the open end of the other end is connected to the oscillation frequency control circuit 15 and the oscillation unit 33 via a capacitor C11. The open end of the carrier signal oscillation stripline 11 is connected to the collector of the grounded-emitter transistor TR3. Strip line 13 for local oscillation signal oscillation
Similarly, one end is grounded and the open end at the other end is the capacitor C.
13 is connected to the oscillation frequency control circuit 15 and the oscillation unit 33 via the line 13, and the open end has a grounded-emitter transistor TR.
It is connected to 4 collectors. Then, by turning on one of the transistors TR3 and TR4 and turning off the other, the carrier signal oscillation strip line 11 and the local oscillation signal oscillation strip line 13 are switched between the carrier signal oscillation and the local oscillation signal oscillation. To use.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oscillator circuit for a wireless communication device or the like.

[0002]

2. Description of the Related Art Conventionally, in a radio communication device that requires signals of different oscillation frequencies during transmission and reception, an oscillation circuit for a carrier signal for transmission and an oscillation circuit for a local oscillation signal for reception are separately provided. There have been realized those which are provided or those which change the oscillation frequency at the time of reception and at the time of transmission by the oscillation frequency control circuit with the oscillation circuit being common.

FIG. 3 is a diagram showing a configuration of a conventional oscillation circuit for changing the control voltage of the oscillation frequency control circuit to generate two oscillation frequencies of a carrier wave signal and a local oscillation signal having different frequency bands.

In the figure, the quarter-wave type strip line 31 is a quarter of the desired oscillation frequency formed on the substrate.
It is a conductor pattern having a wavelength length, one end of which is grounded, and the other end of which is open (a terminal on the non-grounded side) is connected to the capacitor C1 of the frequency control circuit 32 and the capacitor C2 of the oscillator 33. This 1/4 wavelength stripline 3
1 acts as an inductance component of the oscillation circuit.

The oscillation frequency control circuit 32 is composed of a capacitor C1 and a varactor diode D1 connected in series, and an inductance L1 connected to the connection point of the capacitor C1 and the varactor diode D1.
One end of the capacitor C1 has a 1/4 wavelength strip line 3
1 is connected to the open end and the other end is a varactor diode D
Connected to the anode of. The cathode of the varactor diode D1 is grounded.

The oscillator 33 includes a transistor TR2 and a capacitor C2 connected to the base of the transistor TR2.
A capacitor C3 connected between the collector and the emitter of the transistor TR2, a capacitor C4 connected between the base and the emitter of the transistor TR2, and a capacitor C5 connected between the emitter of the transistor TR2 and the base of the transistor TR1. It consists of and.

The transistor TR2 of the oscillator 33 and the capacitors C3 and C4 form a Colpitts type oscillation circuit, and the inductance of the 1/4 wavelength type stripline 31 and the capacitance of the varactor diode D1 of the oscillation frequency control circuit 32. Then, oscillation is performed at a frequency determined by the capacitances of the capacitors C3 and C4. In this oscillation circuit, the capacitance of the varactor diode D1 is changed by changing the control voltage supplied to the oscillation frequency control circuit 32, and the oscillation frequency is controlled to be the target frequency.

The buffer amplifier 34 is a transistor TR.
1, an inductance L2 connected between the collector of the transistor TR1 and the power supply terminal, a capacitor C6 connected between the collector of the transistor TR1 and the output terminal, and a bias voltage to the bases of the transistors TR1 and TR2. It is composed of resistors R1, R2, and R3 to be supplied. The capacitors C7, C8 and C9 are bypass capacitors.

The oscillation signal output from the emitter of the transistor TR2 of the oscillator 33 is output to the base of the transistor TR1 of the buffer amplifier 34 via the capacitor C5, amplified by the transistor TR1 and output to another circuit.

[0010]

By the way, in the oscillation circuit having the above-mentioned structure, the frequency control range of the oscillation frequency control circuit is widened in order to generate the carrier wave signal and the local oscillation signal whose frequency bands are widely separated from each other. It was necessary to make the frequency control sensitivity very large. Therefore, the oscillation frequency fluctuates significantly due to noise input to the control terminal of the oscillation frequency control circuit, and the CNR (Carrier-to-noise) of the oscillation circuit is changed.
There was a problem that the power ratio) characteristic deteriorates.

In order to solve this problem, a carrier signal oscillation circuit and a local oscillation signal oscillation circuit may be provided separately, but such a configuration would increase the circuit scale.

An object of the present invention is to provide an oscillator circuit which can obtain good CNR characteristics and can be reduced in circuit scale.

[0013]

An oscillator circuit according to a first aspect of the present invention is an oscillator circuit, an oscillation frequency control circuit, one end of which is grounded and the other open end of which is connected to the oscillator unit and the oscillation frequency control circuit. A strip line for oscillating a carrier signal, a local oscillation signal oscillating strip line whose one end is grounded and an open end at the other end is connected to an oscillating unit and an oscillation frequency control circuit, and an open end of the strip line for oscillating a carrier signal. And a ground, and a first switching circuit that grounds the open end of the carrier signal oscillation stripline and the local oscillation signal oscillation that is connected between the open end of the local oscillation signal oscillation stripline and ground. The second switching circuit grounds the open end of the strip line.

Further, in the oscillator circuit of the second invention, the oscillator section, the oscillation frequency control circuit, one short-circuited end is grounded via the capacitor, and the other end is connected to the oscillator section and the oscillation frequency control circuit. A carrier signal oscillation stripline, a local oscillation signal oscillation stripline whose one end is grounded via a capacitor and the other end is connected to an oscillation unit and an oscillation frequency control circuit, and a carrier signal oscillation stripline Is connected between the short-circuit end of the carrier signal oscillation strip line and the first switching circuit that grounds the short-circuit end of the carrier signal oscillation strip line, and the short-circuit end of the local oscillation signal oscillation strip line is connected to the ground. The second switching circuit grounds the short-circuited end of the signal oscillation strip line.

An oscillator circuit according to a third aspect of the present invention includes an oscillator section, an oscillation frequency control circuit, a carrier signal oscillation stripline whose one end is grounded, a local oscillation signal oscillation stripline whose one end is grounded, and a carrier wave. A first switching circuit that connects the other end of the signal oscillation strip line to the oscillation unit and the oscillation frequency control circuit; and a first switching circuit that connects the other end of the local oscillation signal oscillation strip line to the oscillation unit and the oscillation frequency control circuit. 2 switching circuits.

[0016]

According to the first aspect of the present invention, during carrier wave oscillation, the second switching circuit is turned on to ground the open end of the local oscillation signal oscillation strip line, the inductance of the carrier signal oscillation strip line, the oscillation section and the oscillation. Oscillate at a frequency determined by the impedance of the frequency control circuit. Further, at the time of local oscillation signal oscillation, the first switching circuit is turned on to ground the open end of the carrier signal oscillation strip line, and the inductance of the local oscillation signal oscillation strip line and the impedance of the oscillation unit and oscillation frequency control circuit are used. Oscillate at the determined frequency.

In the second invention, when the carrier signal is oscillated,
The first switching circuit is turned on to ground the short-circuit end of the carrier signal oscillating strip line and oscillate at a frequency determined by the inductance of the carrier signal oscillating strip line and the impedance of the oscillator and the oscillation frequency control circuit. During local oscillation signal oscillation, the second switching circuit is turned on to ground the short-circuit end of the local oscillation signal oscillation strip line, and the inductance of the local oscillation signal oscillation strip line and the impedance of the oscillation unit and the oscillation frequency control circuit are used. Oscillate at the determined frequency.

Further, in the third invention, when the carrier signal oscillates, the carrier signal oscillating strip line is connected to the oscillating section and the oscillating frequency control circuit by the first switching circuit, and the carrier signal is oscillated at a frequency determined by the impedances thereof. Generate. At the time of local oscillation signal oscillation, the second switching circuit connects the local oscillation signal oscillation strip line to the oscillation unit and the oscillation frequency control circuit to generate a local oscillation signal at a frequency determined by the impedances of the strip lines.

That is, in the first, second and third inventions, the carrier signal oscillating strip line and the local oscillating signal oscillating strip line are used by switching between the carrier signal oscillating and the local oscillating signal oscillating. Because I chose
Good CNR characteristics can be obtained by lowering the frequency control sensitivity of the oscillation frequency control circuit. Further, since the oscillating unit and the oscillation frequency control circuit are shared during the carrier wave signal oscillation and the local oscillation signal oscillation, the circuit scale can be reduced and a smaller radio communication device can be realized.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit configuration diagram of an oscillator circuit according to a first embodiment of the present invention. In the first embodiment, switching circuits are connected between the open end of the carrier signal oscillation strip line and the ground and between the open end of the local oscillation signal oscillation strip line and the ground, respectively, and the carrier signal oscillation strip line and the local oscillation are connected. The signal oscillation strip line is switched and used. Hereinafter, the same parts as those of the conventional oscillation circuit shown in FIG.

In FIG. 1, one end of the carrier signal oscillation strip line 11 is grounded, and the other end of the strip line 11 is connected to the capacitor C1 of the oscillation frequency control circuit 15 and the capacitor C2 of the oscillator 33 via the capacitor C11. ing. The collector of the grounded-emitter transistor TR3 is connected to the open end of the carrier signal oscillation stripline 11, the resistor R11 and the capacitor C12 are connected in parallel to the base of the transistor TR3, and the base is connected via the resistor R12. Grounded. Resistor R11
And the other end of the capacitor 12 is a switch terminal (SW terminal)
The transistor TR3 is turned on and off by a signal input to the switch terminal. The transistor TR3 constitutes a first switching circuit 12 which grounds the open end of the carrier signal oscillation strip line 11.

Strip line 13 for local oscillation signal oscillation
Has one end grounded and the other open end having a capacitor C13.
The capacitor C1 of the oscillation frequency control circuit 15 and the capacitor C2 of the oscillator 33 are connected via The collector of the grounded-emitter transistor TR4 is connected to the open end of the local oscillation signal oscillation stripline 13. A resistor R13 and a capacitor C14 are connected in parallel to the base of the transistor TR4, and the base of the transistor TR4 is grounded via the resistor R14. The other ends of the resistor R13 and the capacitor C14 are connected to the switch terminal, and the transistor TR4 is turned on / off by a signal input to the switch terminal. The transistor TR4 constitutes a second switching circuit 14 which grounds the open end of the local oscillation signal oscillation strip line 13.

Next, the operation of the oscillator circuit having the above configuration will be described. First, at the time of carrier wave signal oscillation, a signal that turns off the transistor TR3 of the first switching circuit 12 and turns on the transistor TR4 of the second switching circuit 14 is supplied to the bases of the transistors TR3 and TR4. When the transistor TR4 is turned on, the open end of the local oscillation signal oscillation stripline 13 is grounded, and the local oscillation signal oscillation stripline 13 is grounded.
Both ends of are short-circuited, and the inductance component becomes zero.

Therefore, the oscillator circuit includes the inductance of the strip line 11 for oscillating the carrier signal, the capacitance of the varactor diode D1 of the oscillation frequency control circuit 15, and the oscillator section 3.
The third transistor TR2 oscillates at a frequency determined by the capacitance of the capacitor C3 connected between the collector and the emitter and the capacitance of the capacitor C4 connected between the collector and the base. The oscillation frequency control circuit 15 includes a PLL (not shown).
A voltage obtained by integrating the output signal of the phase comparator composed of a circuit and the like with a low-pass filter and converting it into a DC voltage is given as a control voltage. The control voltage changes the capacitance of the varactor diode D1 to oscillate the carrier signal. The frequency is controlled to the target frequency.

Next, when the local oscillation signal oscillates, the transistor TR4 of the second switching circuit 14 is turned off and the first switching circuit 14 is turned off.
A signal for turning on the transistor TR3 of the switching circuit 12 is supplied to the bases of the transistors TR4 and TR3. When the transistor TR3 is turned on, the open end of the carrier signal oscillation strip line 11 is grounded, both ends of the carrier signal oscillation strip line 11 are short-circuited, and the inductance component becomes zero.

Therefore, the oscillation circuit is connected between the inductance of the local oscillation signal oscillation strip line 13, the capacitance of the varactor diode D1 of the oscillation frequency control circuit 15 described above, and the collector and emitter of the transistor TR2 of the oscillation unit 33. The capacitance of the capacitor C3, the collector,
It oscillates at a frequency determined by the capacitance of the capacitor C4 connected between the bases. The control voltage supplied to the oscillation frequency control circuit 15 changes the capacitance of the varactor diode D1 to control the oscillation frequency of the local oscillation signal to a target frequency.

That is, the carrier signal oscillation strip line 11 and the local oscillation signal oscillation strip line 13 are switched between when the carrier signal oscillates and when the local oscillation signal oscillates, and the oscillation frequency is determined by the inductance of these strip lines. Therefore, the frequency control range of the frequency control circuit 15 is only required to control the oscillation frequency to a target frequency in each oscillation frequency band, and the frequency control sensitivity can be set low. Therefore, the frequency modulation component due to noise or the like can be reduced, and good CNR characteristics can be obtained. Further, since the carrier oscillation frequency band is switched to the local oscillation frequency band, and vice versa, the local oscillation frequency band is switched to the carrier oscillation frequency band by switching the collector bias of the transistors TR3 and TR4. Can be switched at high speed.

Further, since the resonance section 33 and the oscillation frequency control circuit 15 are shared during the oscillation of the carrier wave signal and the oscillation of the local oscillation signal, the circuit scale can be made smaller than the conventional circuit which requires two oscillation circuits. Moreover, the frequency control sensitivity of the oscillation frequency control circuit 15 can be designed to a value equivalent to that when two oscillation circuits are provided.

Next, a second embodiment of the present invention in which a switching circuit is connected between the short-circuit end of the carrier signal oscillation strip line 11 and the ground and between the short-circuit end of the local oscillation signal oscillation strip line 13 and the ground is shown in FIG. 2 will be described.

The parts different from the first embodiment described above will be described below. Strip line for carrier signal oscillation 1
1 open end and local oscillation signal oscillation stripline 13
The open ends of are connected to the capacitor C1 of the oscillation frequency control circuit 15 and the capacitor C2 of the oscillator 33, respectively. The short-circuited end at the other end of the carrier signal oscillation stripline 11 is grounded via a capacitor C21 and is further connected to the collector of a grounded-emitter transistor TR3. When a bias voltage is supplied to the base of the transistor TR3 to turn on the transistor TR3,
The short-circuited end of the carrier signal oscillation strip line 11 is grounded, and the carrier signal oscillation strip line 11 functions as an oscillation element of the oscillation circuit.

Similarly, the other short-circuit end of the local oscillation signal oscillating strip line 13 is grounded via the capacitor C22 and is also connected to the collector of the grounded-emitter transistor TR4. When a bias voltage is supplied to the base of the transistor TR4 to turn on the transistor TR4, the local oscillation signal oscillation stripline 13 is generated.
Is grounded, and the local oscillation signal oscillation stripline 13 functions as an oscillation element of the oscillation circuit.

Next, the operation of the oscillation circuit of the second embodiment having the above configuration will be described. When the carrier wave signal oscillates, a signal that turns on the transistor TR3 of the first switching circuit 12 and turns off the transistor TR4 of the second switching circuit 14 is applied to each of the transistors TR3 and TR4.
Supplied to the base of. When the transistor TR4 is turned off, the short-circuit end of the local oscillation signal oscillation strip line 13 is not directly grounded, so that the inductance of the local oscillation signal oscillation strip line 13 has a value that does not affect the oscillation frequency. Therefore, the oscillation circuit oscillates at a frequency determined by the inductance of the carrier signal oscillation strip line 11 and the capacitance of the varactor diode D1 of the oscillation frequency control circuit 15. Then, the capacitance of the varactor diode D1 is changed by the control voltage supplied to the oscillation frequency control circuit 15 in this state, and the oscillation frequency of the carrier signal is controlled to the target frequency.

At the time of local oscillation signal oscillation, a signal for turning off the transistor TR3 of the first switching circuit 12 and turning on the transistor TR4 of the second switching circuit 14 is supplied to the bases of the respective transistors TR3, TR4. . When the transistor T3 is turned off, the short-circuited end of the carrier signal oscillation strip line 11 is not directly grounded, so that the carrier signal oscillation strip line 11 is not grounded.
The inductance has a value that does not affect the oscillation frequency.
Therefore, the oscillator circuit oscillates at a frequency determined by the strip line for oscillating the local oscillation signal and the capacitance of the varactor diode of the frequency control circuit 15. Then, in this state, the oscillation frequency of the local oscillation signal is controlled to the target frequency by the control voltage supplied to the oscillation frequency control circuit 15.

In the second embodiment, the carrier signal oscillation strip line 11 and the local oscillation signal oscillation strip line 13 are switched between the carrier signal oscillation and the local oscillation signal oscillation as in the first embodiment. Since the oscillation frequency is determined by the inductance of these strip lines, the frequency control circuit 15 does not need to have a wide frequency control range, and the frequency control sensitivity can be lowered. Therefore, the frequency modulation component due to noise or the like can be reduced, and CNR characteristics can be prevented from being degraded.

Further, since the oscillation frequency control circuit 15, the oscillating unit 33, etc. are shared between the carrier signal oscillation and the local oscillation signal oscillation, the circuit scale is larger than that of the conventional oscillation circuit having two systems of these circuits. The size of the wireless communication device can be reduced.

Further, since the carrier signal oscillation strip line and the local oscillation signal strip line are switched by switching the collector bias, two frequency bands of the carrier signal and the local oscillation signal can be switched at high speed. The present invention can be applied to an oscillation circuit of a wireless communication system that switches transmission / reception at high speed like the TDD system.

The first and second switching circuits 1
2 and 14 are inserted in series in the carrier signal oscillation strip line and the local oscillation signal oscillation strip line 13, respectively, and when the carrier signal oscillates, the first switching circuit 12 is turned on to turn on the carrier signal oscillation strip line 11.
Is connected to the oscillation unit and the oscillation frequency control circuit, and the carrier signal oscillation stripline 11 is used as an oscillation element. When the local oscillation signal oscillates, the second switching circuit is turned on to turn on the local oscillation signal oscillation stripline 13. May be connected to the oscillation unit and the oscillation frequency control circuit, and the local oscillation signal oscillation stripline 13 may be used as an oscillation element.

Further, the oscillation circuit of the present invention is not limited to the oscillation frequency control circuit 15 composed of the varactor diode and the oscillation unit 33 composed of the Colpitts oscillation circuit described in the embodiments, and is applied to the oscillation circuits of other configurations. it can. Further, the switching circuit can also be configured by circuits other than those described in the embodiments.

[0039]

According to the present invention, the carrier signal oscillation strip line and the local oscillation signal oscillation strip line are switched by the first and second switching circuits, and the carrier signal oscillation strip line or the local oscillation signal oscillation strip line is selected. Since the oscillation frequency is controlled by the oscillation frequency control circuit in the state of being oscillated at the frequency determined by the inductance and the like, the frequency control range of the oscillation frequency control circuit can be narrowed. Therefore, the frequency control sensitivity of the frequency control circuit can be lowered to obtain good CNR characteristics. Further, since the resonance part, the oscillation frequency control circuit and the like are shared by the carrier signal oscillation and the local oscillation signal oscillation, the circuit scale can be reduced and a small radio communication device can be realized.

[Brief description of drawings]

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

FIG. 2 is a circuit configuration diagram of an oscillator circuit according to a second embodiment of the present invention.

FIG. 3 is a circuit configuration diagram of a conventional oscillator circuit.

[Explanation of symbols]

 11 Carrier Wave Signal Oscillation Stripline 12 First Switching Circuit 13 Local Oscillation Signal Oscillation Stripline 14 Second Switching Circuit 15 Oscillation Frequency Control Circuit 33 Oscillator

Claims (4)

[Claims] 1. An oscillating unit, an oscillating frequency control circuit for controlling an oscillating frequency of the oscillating unit, one end of which is grounded, and an open end of the other end of which is a carrier signal oscillating circuit connected to the oscillating unit and the oscillating frequency control circuit. Strip line for local oscillation signal oscillation, one end of which is grounded and the other end of which is open end is connected to the oscillation unit and the oscillation frequency control circuit, and between the open end of the carrier signal oscillation strip line and the ground Connected to the first switching circuit for grounding the open end of the carrier signal oscillation strip line, and between the open end of the local oscillation signal oscillation strip line and the ground, and for connecting the local oscillation signal oscillation strip line to the ground. An oscillation circuit comprising: a second switching circuit having an open end grounded. 2. An oscillating section, an oscillating frequency control circuit for controlling an oscillating frequency of the oscillating section, one end of which is connected to the oscillating section and the oscillating frequency control circuit,
The short-circuited end at the other end is a carrier signal oscillation stripline grounded to the ground via a capacitor, and one end is connected to the oscillation unit and the oscillation frequency control circuit,
A short-circuited end of the carrier wave signal is connected between the local oscillation signal oscillating stripline whose grounding end is grounded via a capacitor and the carrier wave signal oscillating stripline and the grounding line. A first switching circuit having its end grounded; and a second switching circuit connected between the short-circuited end of the local oscillation signal oscillating stripline and the ground and grounding the short-circuited end of the local oscillation signal oscillating stripline An oscillation circuit characterized by the above. 3. The oscillator circuit according to claim 1, wherein the carrier signal oscillation strip line and the local oscillation signal oscillation strip line are quarter-wave strip lines. 4. An oscillating unit, an oscillating frequency control circuit for controlling an oscillating frequency of the oscillating unit, a carrier signal oscillating strip line having one end grounded, and a local oscillating signal oscillating strip line having one end grounded. When the other end of the carrier signal oscillation strip line is connected to the oscillation frequency control circuit and the oscillation unit, a first switching circuit is provided, and the other end of the local oscillation signal oscillation strip line is connected to the oscillation frequency control circuit and the oscillation unit. And a second switching circuit for connecting to the unit.