JPH11289220A - Wide band voltage controlling oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wide band voltage controlling oscillator capable of controlling frequency bands in a wide range. SOLUTION: A control circuit 115 reads out a voltage value for determining an inductance value for a variable inductor 104 corresponding to specific frequency from a storage circuit 116 based on a signal indicating the specific frequency and outputs the read value to the inductor 104, which discretely changes the resonance frequency of a resonance part, the capacity of a varactor diode 102 is made variable and its phase is fixed by DC voltage inputted from a PLL IC control terminal 101, and frequency oscillation in a wide range is executed by a transistor 109.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wide band voltage controlled oscillator, and more particularly to a wide band capable of obtaining stable oscillation in respective frequency bands corresponding to a plurality of communication systems existing over a wide range by controlling an external voltage. The present invention relates to a voltage controlled oscillator.

[0002]

2. Description of the Related Art A conventional voltage controlled oscillator supports only a specific frequency, and it is generally difficult to realize a small oscillator capable of controlling the frequency in a region where a single fractional band is large. Using a conventional VCO (Voltage Controlled Oscillator), for example, PDC (Personal Digital Cellular) and P
In order to cope with the HS (Personal Handyphone System), it cannot be made variable only by a varactor diode that electrically controls the oscillation frequency, and the physical length of the resonator in the oscillator must be changed.

Since this is not possible with a single-sized resonator, a conventional wide-band oscillator divides a covering frequency band into a plurality of narrow bands and obtains a narrow band corresponding to each narrow band in order to obtain wide-band oscillation. A method has been used in which a plurality of oscillators are installed and a desired frequency is obtained by switching with a switch or the like. For the above method, see the 1996 IEICE Communications Society Conference B-360 "Software
Radio local oscillation frequency accuracy ".

[0004]

However, the above-mentioned conventional voltage controlled oscillator has a problem that it cannot be miniaturized because a plurality of narrow band oscillators are required to support a wide band. Was.

As a fundamental problem, the basic structure of an oscillator is composed of a resonator and an active device, but in a conventional resonator, the physical size must be changed in order to greatly change the resonance frequency. Rather, wideband frequency tunability was virtually impossible.

The present invention has been made in view of the above circumstances, and has as its object to provide a wide band voltage controlled oscillator capable of controlling a wide range of frequencies.

[0007]

According to a first aspect of the present invention, there is provided a wide band voltage controlled oscillator comprising: an active element for oscillation; and a frequency oscillated by the active element. It is characterized by comprising a variable inductor that is discretely switched, and a varactor diode that continuously controls the discretely switched frequency to fix the phase, and can control a wide range of frequencies.

According to a second aspect of the present invention, there is provided a storage circuit for storing a voltage value for controlling a variable inductor corresponding to a frequency in the wideband voltage controlled oscillator according to the first aspect. And a control circuit for reading a voltage value corresponding to the specific frequency from the storage circuit by inputting a signal indicating the specific frequency from the outside, and controlling the variable inductor with the voltage of the voltage value. The discrete frequency switching can be facilitated, and a wide range of frequencies can be controlled.

According to a third aspect of the present invention, there is provided a wide band voltage controlled oscillator comprising: a transistor for oscillating a bias voltage by an input signal; and a frequency oscillated by the transistor. A variable inductor to be switched, a varactor diode that continuously controls the discretely switched frequency to fix the phase, a storage circuit that stores a voltage value that controls the variable inductor corresponding to the frequency, A control circuit that reads a voltage value corresponding to the specific frequency from the storage circuit by inputting a signal indicating a specific frequency from the storage circuit and controls the variable inductor with the voltage of the voltage value, wherein a base of the transistor and an input signal are provided. A first capacitor, a second capacitor,
A first resistor connected in series, the varactor diode connected in parallel between the input terminal and the first capacitor, and a variable resistor connected between the first capacitor and the first resistor. An inductor is connected in parallel, a bias voltage terminal to which the bias voltage is applied is connected to the collector of the transistor, and a second resistor is connected in series between the base of the transistor and the bias voltage terminal. , A third resistor is connected in parallel between the first resistor and the base of the transistor, and a third capacitor is connected in series between the emitter of the transistor and an output terminal from which an output signal is output. Between the emitter of the transistor and the third capacitor.
Are connected in parallel,
Discrete frequency switching can be facilitated, and a wide range of frequencies can be controlled.

According to a fourth aspect of the present invention, there is provided a wide band voltage controlled oscillator according to the second or third aspect, wherein information for determining an inductance constant of a variable inductor in a storage circuit is provided. It is preferable that the inductance constant is set so as to decrease as the oscillation frequency of the wideband voltage controlled oscillator increases.

The invention according to claim 5 for solving the problem of the above-mentioned conventional example is according to claim 2 or 3 or 4.
In the variable inductor of the broadband voltage controlled oscillator according to the description, an inductance element configured by a plurality of coils or a plurality of strip lines or a plurality of chip inductors,
The first to remove the DC component of the current and pass the AC component
, A choke coil for passing a DC current, a plurality of second capacitors for passing a high-frequency signal, a third capacitor for removing a DC component of the current and passing an AC component, and being turned on by voltage application. A plurality of PIN diodes that allow current to flow, and a control circuit that selectively outputs an applied voltage, wherein the inductance element, the third capacitor, and the first capacitor are provided between an input terminal and an output terminal. The choke coil is connected in parallel between the inductance element and the first capacitor, and one end of the plurality of second capacitors is connected to a plurality of taps provided on the inductance element. The other end of the second capacitor is connected to the control circuit, and the anodes of the plurality of PIN diodes are connected to the control circuit. The plurality of PIN diodes are respectively connected to lines connecting the path and the plurality of second capacitors, and the cathode sides of the plurality of PIN diodes are connected between the inductance element and the first capacitor; Is input, the second capacitor and the PIN correspond to the voltage.
It is characterized by a control circuit for selectively applying a voltage to the diode, and the target inductance can be easily adjusted.

[0012]

Embodiments of the present invention will be described with reference to the drawings. The wideband voltage controlled oscillator according to the embodiment of the present invention is configured such that the control circuit reads a voltage value that determines an inductance value of the variable inductor corresponding to the specific frequency from the storage circuit by using a signal indicating the specific frequency input from the outside, and is variable. The voltage is output to the inductor, the variable inductor discretely changes the oscillation frequency input from the input terminal, and the phase is fixed by the variable capacitance of the varactor diode to enable wide-band frequency oscillation by the transistor. .

A broadband voltage controlled oscillator (this oscillator) according to an embodiment of the present invention will be described with reference to FIG. FIG.
1 is a circuit diagram of a wideband voltage controlled oscillator (present oscillator) according to an embodiment of the present invention. As shown in FIG. 1, the oscillator includes a variable inductor 104 and a varactor diode 102 as a resonance unit, and a transistor 10 as an active circuit unit.
9 and a control circuit 115 for controlling the variable inductor 104.
And a storage circuit 116.

Specifically, the transistor 10 of the present oscillator
9 is provided with a PLL IC control terminal 101 connected to the base B, and capacitors 103 and 105 and a resistor 106 are connected in series between the terminal 101 and the transistor 109.

A varactor diode 102 is connected in parallel between the PLL IC control terminal 101 and the capacitor 103, a variable inductor 104 is connected in parallel between the capacitor 103 and the capacitor 105, and a resistor 106 and a transistor 109 are connected. A bias voltage is applied from the bias voltage terminal 112 to the base B via the resistor 107, and one end of the resistor 108 whose other end is grounded is connected.

A bias voltage is applied to the collector C of the transistor 109 via a bias voltage terminal 112.
The emitter E of the transistor 109 is connected to the output terminal 113 via a capacitor 111, and one end of a resistor 110 whose other end is grounded is connected between the emitter E of the transistor 109 and the capacitor 111.

In order to control the variable inductor 104, a control circuit 115 is connected to the variable inductor 104, and a value for controlling the variable inductor 104 is stored in a storage circuit 116.
An external control input terminal 114 is connected to a control circuit 115 so that a signal can be input from outside to adjust the signal.

Next, each part of the oscillator will be described.
The varactor diode 102 is a variable capacitance diode. In principle, the varactor diode 102 changes the thickness of the depletion layer according to the magnitude of the reverse voltage applied to the barrier capacitance of the pn junction, and adjusts the capacitance value. In the present embodiment, the frequency is continuously controlled in a specific range to fix and stabilize the phase. Specifically, the changing capacitance of the varactor diode 102 is, for example, 2 to 6 pF.
It is.

The variable inductor 104 includes a control circuit 115
The oscillation frequency is discretely switched according to the DC voltage input from the CPU. That is, the oscillation frequency is switched to a specific frequency by setting the inductance value of the variable inductor 104 to a specific value by the voltage from the control circuit 115. The specific configuration and operation of the variable inductor 104 will be described later.

The transistor 109 is an active element for oscillation, and outputs a bias voltage supplied to the collector C to the emitter E according to the resonance frequency inputted from the base B. That is, the transistor 104 oscillates the bias voltage applied to the collector C by the resonance frequency input to the base B and outputs the oscillated frequency to the emitter E.

The storage circuit 116 stores control voltage information of an optimum oscillation frequency corresponding to each communication system. Specifically, the control voltage information is set to a value that decreases the inductance value of the variable inductor 104 as the oscillation frequency increases. Control circuit 11
5 is a memory circuit 116 that allows the variable inductor 104 to obtain a required inductance value according to each communication method.
To output an optimal DC voltage preset in advance.

Here, the resonance frequency of the resonator having the varactor diode 102 and the variable inductor 104 is
The characteristic is that the frequency can be electrically varied over a wide range by external voltage control. Since the oscillation frequency of the oscillator changes relatively when the resonance frequency of the resonator unit is varied, the oscillation frequency can be similarly controlled over a wide band if the resonance frequency of the resonator unit can be controlled over a wide band.

The oscillation frequency is determined using the following two variable elements. One is to use the variable inductor 104 to switch the frequency discretely over a wide range. In this control, information on the target frequency band is externally input to the control circuit 115 through the external control input terminal 114. The control circuit 115 reads the control voltage information from the storage circuit 116 based on this signal, and outputs a DC voltage so that the variable inductor 104 can obtain a required inductance value.

The other is that the varactor diode 102 controls the frequency continuously in a relatively narrow frequency band.
Is used. To this, a control voltage for obtaining a resonance frequency from an external PLL IC is applied to the PLL IC control terminal 101, and fine adjustment of the oscillation frequency and switching of the frequency channel are performed. The oscillation output is output through the output terminal 113. With the above configuration, a voltage controlled oscillator capable of controlling an electrically wide frequency band is realized.

The relationship between the inductance value and the capacitance value of the resonance frequency of the resonator section of the oscillator will be described with reference to FIG. FIG. 2 is a diagram showing how the resonance frequency and the capacitance value and the inductance value change. The horizontal axis is the resonance frequency [MHz], the vertical axis is the capacitance of the capacitance [pF], and the inductance values are 2, 4, 6, respectively.
It is a graph at the time of a value of 8, 10 nH. Assuming that the varactor diode used for variable capacitance changes at 2 to 6 pF, for example, when the inductor of the resonator is a fixed value of 6 nH or more, the frequency of 1450 MHz or more cannot be controlled. Similarly, if it is less than 6 nH, it is impossible to change the frequency below 850 MHz, and if the linearity of the oscillation frequency with respect to the external control voltage is required, the frequency range is narrowed.

As is apparent from the above, it is not possible to make the oscillator wider in bandwidth without changing the inductor. For example, Table 1 shows the inductance value in each frequency band when the capacitance of the varactor diode changes most linearly with respect to the bias voltage near 4 pF. The remarks indicate the communication method used in each frequency band.

[0027]

[Table 1]

By using a variable inductor which can be electrically switched as needed to the above-described inductance value, an oscillator corresponding to a wide frequency band can be constructed.

Next, a variable inductor used in the present oscillator will be described with reference to FIG. FIG. 3 is an equivalent circuit diagram of the variable inductor in the wideband voltage controlled oscillator according to the embodiment of the present invention. When a control voltage is input from the control circuit 115 of FIG. 1 via the input terminal 213, the variable inductor is controlled by the capacitors 205, 206, 207 and P so that the control circuit 212 can obtain a desired inductance value.
A voltage is selectively applied to the IN diodes 209, 210, 211. This selection will determine the inductance value.

Then, the signal input from the input terminal 201 has its DC component removed via the applied capacitor, and the AC component (high frequency component) is output to the PIN diode. Since the PIN diode is turned on by application of a voltage from the control circuit 212, a high-frequency component and a DC component from the control circuit 212 are output from the cathode of the PIN diode.

Then, by the choke coil 204,
The DC component from the control circuit 212 flows, and only the high frequency component passes through the bias current cut capacitor 208,
The signal is output from the output terminal 202.

The variable inductor circuit is described in Japanese Patent Application Laid-Open No. Hei 6-276003, which changes the length of the characteristic impedance portion by selecting an intermediate lead wire by a tap selection circuit according to the frequency. Further, the inductance of the variable capacitor is changed by changing the capacitance of the variable capacitor.

On the other hand, in the variable inductor according to the embodiment of the present invention, a voltage is applied to the capacitors 205, 206, and 207 connected in the middle of the inductance element 203, and the voltage is applied through the capacitors 205, 206, and 207. Since the high frequency component is taken in and output, the control circuit 212 can adjust the inductance only by applying a voltage to the capacitor so as to correspond to the target frequency band. This is different from the inductor circuit.

According to the wide-band voltage controlled oscillator according to the embodiment of the present invention, control circuit 115 determines the inductance value of the variable inductor corresponding to the specific frequency from storage circuit 116 by the signal indicating the specific frequency input from the outside. The variable inductor 10 reads the voltage value
4 and the variable inductor 104 discretely changes the resonance frequency.
Then, the capacity is made variable by the DC voltage input from the PLL IC control terminal 101, the phase is fixed, and the transistor 10
9, frequency oscillation in a wide band is performed, so that there is an effect that a stable oscillator can be obtained in a wide frequency band, which cannot be handled by a conventional voltage controlled oscillator.

Further, according to the variable inductor according to the embodiment of the present invention, the capacitors 205, 206, and 20 connected in parallel to the tap in the middle of the inductance element 203.
7, a voltage is selectively applied from the control circuit 212 to the other end of
The AC component of the signal input from the input terminal 201 is input from the capacitor, and the PIN diodes 209 and 21
Since the output is made via 0 and 211, there is an effect that the target inductance can be easily adjusted.

[0036]

According to the present invention, the frequency oscillated by using the active element is discretely switched by the variable inductor, and the discretely switched frequency is continuously controlled by the varactor diode to fix the phase. The wideband voltage controlled oscillator has the effect of controlling a wide range of frequencies.

[Brief description of the drawings]

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

FIG. 2 is a diagram illustrating a state of changes in a resonance frequency, a capacitance value, and an inductance value.

FIG. 3 is an equivalent circuit diagram of a variable inductor in the wideband voltage controlled oscillator according to the embodiment of the present invention.

[Description of Signs] 101: PLL IC control terminal, 102: Varactor diode, 103, 105, 111: Capacitor, 104
... variable inductors, 106,107,108,110
... Resistance, 109 ... Transistor, 112 ... Bias voltage terminal, 113 ... Output terminal, 114 ... External control input terminal, 115 ... Control circuit, 116 ... Storage circuit,
201: input terminal, 202: output terminal, 203: inductor component, 204: choke coil, 205,
206, 207, 208, 214: bias current cutting capacitor; 209, 210, 211: PIN diode; 212: control circuit; 213: control input terminal

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kenzo Urabe 3-14-20 Higashinakano Nakano-ku Tokyo

Claims (5)

[Claims] 1. An active element for oscillation, a variable inductor for discretely switching a frequency oscillated by the active element, and a varactor diode for continuously controlling the discretely switched frequency to fix a phase. And a broadband voltage controlled oscillator. 2. A storage circuit for storing a voltage value for controlling a variable inductor corresponding to a frequency, and a voltage value corresponding to the specific frequency is read from the storage circuit by input of a signal indicating the specific frequency from outside, The wideband voltage controlled oscillator according to claim 1, further comprising a control circuit for controlling the variable inductor with the voltage having the voltage value. 3. A transistor for oscillating a bias voltage according to an input signal, a variable inductor for discretely switching a frequency oscillated by the transistor, and a phase fixed by continuously controlling the discretely switched frequency. A varactor diode, a storage circuit for storing a voltage value for controlling the variable inductor corresponding to the frequency, and reading a voltage value corresponding to the specific frequency from the storage circuit by inputting a signal indicating a specific frequency from the outside, A control circuit for controlling the variable inductor with the voltage having the voltage value, wherein a first capacitor, a second capacitor, and a second capacitor are provided between a base of the transistor and an input terminal to which an input signal is input. And the varactor diode is connected in parallel between the input terminal and the first capacitor. Connected, the variable inductor is connected in parallel between the first capacitor and the first resistor, a bias voltage terminal to which the bias voltage is applied is connected to a collector of the transistor, and a base of the transistor is connected. A second resistor is connected in series between the first resistor and the bias voltage terminal; a third resistor is connected in parallel between the first resistor and the base of the transistor; A third capacitor is connected in series between an output terminal from which an output signal is output, and a fourth resistor is connected in parallel between the emitter of the transistor and the third capacitor. Wideband voltage controlled oscillator. 4. The information determining the inductance constant of the variable inductor in the storage circuit is set so that the higher the oscillation frequency of the wideband voltage controlled oscillator, the smaller the inductance constant. The wideband voltage controlled oscillator according to claim 2 or claim 3. 5. The variable inductor according to claim 2, wherein the inductance element includes a plurality of coils, a plurality of strip lines, or a plurality of chip inductors, and a DC component of a current is removed. A first capacitor that passes an AC component, a choke coil that passes a DC current, a plurality of second capacitors that pass a high-frequency signal, a third capacitor that removes a DC component of the current and passes an AC component, A plurality of PIN diodes that are turned on by applying a voltage to flow a current, and a control circuit that selectively outputs an applied voltage, wherein the inductance element and the third capacitor are provided between an input terminal and an output terminal; The first capacitor is connected in series, and the choke is provided between the inductance element and the first capacitor. One end of each of the plurality of second capacitors is connected to a plurality of taps provided on the inductance element.
The other end of the capacitor is connected to the control circuit, the anode side of the plurality of PIN diodes is connected to a line connecting the control circuit and the plurality of second capacitors, respectively, and the cathode side of the plurality of PIN diodes is When the control circuit is connected between an inductance element and the first capacitor and receives a voltage for obtaining a target inductance value, the second capacitor and the PIN correspond to the voltage. A variable inductor, which is a control circuit for selectively applying a voltage to a diode.