JP3318504B2 - Voltage controlled high frequency oscillator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dual-mode voltage-controlled high-frequency oscillator which derives two oscillation output signals.

[0002]

2. Description of the Related Art Hitherto, there has been known a voltage-controlled high-frequency oscillator used as a transmission oscillator of a mobile communication device or another communication device and a local oscillator of a receiver.

Recently, various mobile communication devices such as mobile phones and car phones have become widespread, but in some communication systems, the shortage of the number of channels has become serious. A new system for solving these problems will be operated. At this stage of widespread use, a dual-band communication device that can use both the conventional system and the new system is required. A dual band communication device needs to use two oscillation output signals of a predetermined frequency, and usually uses two oscillators with different oscillation frequency bands.

As described above, for example, when two oscillators are used in one mobile communication device, the communication device naturally becomes large, and in particular, goes against the miniaturization of the mobile communication device.

As a conventional voltage-controlled oscillator, a voltage-controlled oscillator for supplying a control voltage of a predetermined value for varying a capacitance component of a varicap diode to an LC resonance circuit including a varicap diode in a resonance circuit portion. in, for example, an oscillation output signal in the vicinity of the oscillation frequency F is 800~900MHz band, the oscillation frequency F ₂ is obtained by the same oscillator the oscillation output signal near 1.9GHz band, the range of variable capacitance of the varicap diode However, it cannot be put into practical use in consideration of the limitation, the variation of the C / N characteristic difference of the oscillation circuit, and the like.

Accordingly, the present inventors can discretely switch the resonance frequency of the resonance circuit as shown in FIG. 3, and for example, the oscillation circuit section X which outputs a fundamental oscillation signal in the vicinity of the 800 to 950 MHz band. A voltage-controlled high-frequency oscillator comprising a frequency multiplier circuit Y for multiplying the fundamental oscillation signal and a filter circuit Z for extracting only the multiplied frequency component is proposed.

[0007] This serves to derive directly the basic oscillation signal of the oscillation circuit part X from the first output terminal OUT _1, performs only the multiplication processing frequency multiplier circuit section Y predetermined integral multiple of the fundamental oscillation signal, a filter circuit through parts Z, it is those derived from the second output terminal OUT _2.

[0008] Thus, from the first output terminal OUT _1, the oscillation frequency 800MHz~950MHz obtained an oscillating output signal in the vicinity of band, from the second output terminal OUT _2, for example, twice the frequency of the oscillation frequency 1.6 An oscillation output signal in the vicinity of the band of about 1.9 MHz can be obtained.

[0009] Moreover, by having a frequency shift circuit (switching circuit) X ₁₁ to the resonant circuit X _1, from the first output terminal OUT ₁ any two range around 800~950MHz band oscillation frequency f ₁ and f ₂ are selectively obtained, and the second
From the output terminal OUT ₂ of the oscillation frequency F ₁ (2 × f ₁ ) and F ₂ (2 × f ₁ ) in the range of 1.6 to 1.9 GHz band.
₂ ) can be obtained selectively.

[0010]

In the voltage-controlled high-frequency oscillator shown in FIG. 3, a circuit section subsequent to the oscillation circuit section X includes a system for processing an oscillation output signal of, for example, 800 to 900 MHz, and a system for processing, for example, 1. Since the two systems for processing the oscillation output signal of 6 to 1.9 GHz are independent,
Even if the first output terminal and the second output terminal are physically shared and used as one output terminal, the circuit configuration cannot be simplified, and it is difficult to achieve a small control voltage type high-frequency oscillator. Met.

The present invention has been devised in view of the above-described problems, and has as its object to integrate a processing system for a fundamental oscillation signal output from an oscillation circuit unit irrespective of a difference in frequency. To provide a voltage-controlled high-frequency oscillator.

[0012]

According to the present invention, there is provided a resonance circuit section in which a control voltage for controlling an oscillation frequency and a switching voltage for switching the oscillation frequency to a different frequency band are supplied, and both voltages operate at a predetermined resonance frequency. An oscillation circuit portion that outputs a basic oscillation signal, a basic oscillation signal processing circuit portion that performs an amplification process or a multiplication process on the basic oscillation signal of the oscillation circuit portion, and an output frequency of the basic oscillation signal processing circuit portion. And a filter circuit unit having a predetermined frequency pass band characteristic, wherein the basic oscillation signal processing circuit unit has a switching element that switches between amplification processing and multiplication processing with the supply of the switching voltage, and The voltage control, wherein the filter circuit section includes a switching element for switching a frequency pass band characteristic in accordance with the supply of the switching voltage. It is a high-frequency oscillator.

[0013]

As described above, in the voltage-controlled high-frequency oscillator according to the present invention, the resonance operation (frequency of the fundamental oscillation signal) of the resonance circuit is discretely controlled by the switching voltage. That is, by supplying the switching voltage of the predetermined voltage, the frequency of the basic oscillation signal output from the oscillation circuit unit A can be switched to at least two types of frequencies f ₁ and f ₂ .

The basic oscillation signal is subjected to either an amplification operation or a multiplication operation in a basic oscillation signal processing circuit section. The amplification operation mode or the multiplication operation mode is determined by supplying a switching voltage to a switching element connected to the basic oscillation signal processing circuit. In other words, the fundamental oscillation signal processing circuit outputs two types of outputs: a frequency-maintained / amplified output and a frequency-multiplied output.

Further, this output is derived as an oscillation output signal via a filter circuit section which switches to at least two frequency pass band characteristics. The switching of the frequency passband characteristic is determined by supplying a switching voltage to a switching element connected to the filter circuit unit.

That is, the switching voltage is supplied to the resonance circuit section of the oscillation circuit section and controls the frequency of the basic oscillation signal, and at the same time, is supplied to the switch element of the basic oscillation signal processing circuit section, and the operation mode of the basic oscillation signal is controlled. , And is supplied to the switch element of the filter circuit section to control the pass frequency band characteristic.

Thus, regardless of the difference in the frequency band of the oscillation output signal, a series of processing systems including an oscillation circuit section for outputting a basic oscillation signal, a basic oscillation signal processing circuit section, and a filter circuit section are provided. The components that make up the unit are more commonly used, the entire circuit is simplified, and downsizing can be achieved.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A voltage-controlled high-frequency oscillator according to the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a voltage controlled high-frequency oscillator according to the first invention, and FIG. 2 is a circuit diagram thereof.

The voltage-controlled high-frequency oscillator according to the present invention includes an oscillation circuit section A, a basic oscillation signal processing circuit section (hereinafter simply referred to as a signal processing circuit section) B capable of switching processing operations, and switching of pass band characteristics. And a possible filter circuit section C.

The oscillation circuit section A includes a resonance circuit section A ₁ composed of a resonance circuit A ₁₀ and a switching circuit A ₁₁ , a negative resistance circuit section A ₂ ,
And a amplifier circuit unit A ₃ Prefecture. A control voltage terminal VT to which a control voltage Vt is supplied is provided to the resonance circuit section A _1.
And the switching voltage Vs for switching the frequency of the fundamental oscillation signal x
Is provided with a switching voltage terminal VS to which the voltage is supplied.

The resonance frequency of the resonance circuit section A ₁ is determined by the resonance circuit A ₁₀ which substantially forms an LC resonance circuit. Further, the switching circuit A ₁₁ is the supply of the switching voltage Vs (H / L), by changing the circuit constant of the aforementioned L-C resonance circuit, discretely controlling the resonance frequency, i.e., upshift frequency, Shift down is performed.

The negative resistance circuit section A ₂ is a circuit including a transistor, a resistor, etc., for stably outputting a frequency satisfying the oscillation condition with the resonance circuit section A ₁ .

The amplifier circuit unit A ₃ is mainly transistors, and the like resistors, and transistors cooperates negative resistance circuit unit A _2, is a circuit for amplifying a signal from the negative resistance circuit unit A ₂ . This amplifier circuit section A ₃ has a bias power supply terminal V
cc and a terminal for outputting a fundamental oscillation signal x.

[0025] Eventually, the oscillator circuit portion A, the resonance circuit portion A ₁ performs the operation at a predetermined resonant frequency, a negative resistance circuit unit A _2, the amplification circuit unit A _3, the control voltage Vt and the switching voltage Vs
And outputs a fundamental oscillation signal x having a frequency corresponding to. This basic oscillation signal x is supplied to the signal processing circuit section B. In particular, the supply of the switching voltage Vs (H / L), the switching circuit A ₁₁ operates, and the control switching the frequency of the fundamental oscillation signal x from f ₁ to f _2.

The control voltage Vt is supplied from a PLL circuit D connected to the outside of the voltage controlled high-frequency oscillator. PLL circuit section D is generated by comparing the oscillation frequency f ₁ or f ₂ and a predetermined reference frequency of the fundamental oscillation signal x which is output from the oscillation circuit A, the control voltage Vt for correcting the deviation of the frequency Then, it is supplied to the control voltage terminal VT. Also, a control voltage for changing to a frequency corresponding to the selected channel of the communication system is created,
It is supplied to the control voltage terminal VT. This PLL circuit section D
Is a temperature-compensated crystal oscillator that is a reference signal oscillation source, PL
The L-IC includes a low-pass filter that determines a predetermined voltage value.

A signal processing circuit section B is connected to the oscillation circuit section A, and a filter circuit section C is connected to the signal processing circuit section B.

The signal processing circuit section B mainly includes a transistor for performing a processing operation, and at the same time, a switching element _B10 for controlling an operation mode of the transistor is connected.

The signal processing circuit section B performs two operation modes for the basic oscillation signal x. One is a frequency maintenance / amplification processing operation mode, and the other is a frequency multiplication processing operation mode. Switching of the operation mode is controlled to the switching element B _1O by the supply of the above-mentioned switching voltage Vs.

The selection of the two operation modes of the signal processing circuit section B is achieved by controlling the operation area of the transistor.
That is, when the operation region of the transistor uses the amplification region of the fundamental wave component of the input signal (basic oscillation signal), the operation mode is the frequency maintenance / amplification processing operation, or the amplification of the nth harmonic component (improvement of the output signal level) When the area is used, the operation mode is the multiplication operation mode.

The setting of the operating region of the transistor, since it is controlled by the operating environment, for example, setting the bias point of the transistor, the base of the transistor switching element B _1O - it is sufficient to connect between the ground.

More specifically, in the frequency maintaining / amplifying operation mode, the signal processing circuit section B outputs the fundamental oscillation signal x having the frequency f ₁ with its output level improved while maintaining the frequency. Further, (performs multiplication of 2-fold) multiplication of the time of the processing mode of operation, two-times the frequency f ₁ of the fundamental oscillation signal x
× f ₁ , the other frequency components, frequency f ₁ ,
The output level is relatively improved as compared with the frequency 3 × f ₁ .

The filter circuit section C mainly comprises a capacitor, a coil and the like, and extracts only a specific frequency component output from the signal processing circuit section B, and at the same time, a switching element for controlling this frequency pass band. C _1O is connected.

Since the pass band differs depending on the operation mode of the signal processing circuit section B, it is necessary to change circuit constants in order to obtain filter characteristics corresponding to each frequency. By ON-OFF of the switching element C _1O, if or is added capacitor or coil of the filter circuit portion C, and or detached, the characteristics of the pass band is a pass band frequency band of the fundamental oscillation signal, the multiplication processing And the case where the set frequency band is set as the pass band.

The output of the specific frequency extracted by the filter circuit section C is extracted from one output terminal OUT as an oscillation output signal.

Next, the actual circuit of the block circuit shown in FIG. 1 will be described with reference to FIG. 2, and the operation of the circuit of FIG. 2 will be described using the operation table of Table 1. In the frequency multiplier circuit section B, it is assumed that the frequency is doubled and the control voltage is constant.

The resonant circuit A _1O constituting the oscillating circuit unit A is
Mainly strip line L _2, a capacitor C _4, it is composed of a variable capacitance element DV, switching circuit unit A ₁₁ is constituted primarily capacitor C _31, a diode Di, a resistor R _31.
The switching circuit A ₁₁ is connected to the ground terminal side of the strip line L _2.

The negative resistance circuit section A ₂ mainly includes the transistor Q
Mainly _2, amplifying circuit unit A ₃ is mainly organized around transistor Q _1. The basic oscillation signal x which is the output of the transistor Q ₁ is outputted to the signal processing circuit unit B via a capacitor C _14.

[0039] For example, when the switching voltage Vs is not supplied (Vs = L level), the diode Di of the switching circuit A ₁₁ operates in the OFF, and the actual electrical length of the strip line L _2, the basic oscillation The frequency of the signal is the reference frequency f
It becomes ₁ .

[0040] The switching voltage Vs is supplied (switching voltage Vs = H level), diodes of the switching circuit A ₁₁ Di
There turned ON, the electric length of the strip line L ₂ is substantially shortened, the frequency of the resonance frequency, fundamental oscillation signal x
Oscillation frequency is shifted up to the te frequency f ₂ (f ₂ >
f ₁ ).

The signal processing circuit section B is composed of a transistor Q ₄ which acts in two modes of operation, further, the transistor Q ₄ are, the transistor Q ₃ is a switch element B _1O determining the operating environment of the transistor Q ₄ It is connected.

[0042] For example, if the base to the switching voltage Vs of the transistor Q ₃ is a switch element B _1O is not supplied (switching voltage Vs = L level), the transistor Q
₃ becomes OFF. As a result, the transistor Q ₄
It operates in the frequency multiplying operation mode. And
The fundamental oscillation signal x (frequency f ₁ ), which is the input signal of the transistor Q ₄ , is a signal in which the output level of the frequency component of F ₁ = 2 × f ₁ has been improved from the collector of the transistor Q ₄ by the frequency double processing. Is output.

[0043] The switching voltage Vs is supplied (switching voltage Vs = H level), the transistor Q ₃ is turned ON, the transistor Q ₄ are, it will operate at a frequency maintaining and amplifying operation modes. The fundamental oscillation signal x (frequency f ₂₎ is the input signal of the transistor Q ₄ are, simply will be amplified output.

The output of the signal processing circuit unit B is output from the collector of the transistor Q ₄ to the filter circuit portion C.

The filter circuit section C mainly includes coils L ₄ , L
_5, is composed of the capacitor C ₁₆ -C _17, at the same time, the transistor Q ₅ is connected to a switch element C _1O.

In the filter circuit section C, the circuit constant of the LC circuit composed of the coils L ₄ and L ₅ and the capacitors C _{16 to} C ₁₇ changes due to the ON / OFF change of the switch element C _{1 O.} It is set so that a specific frequency band corresponding to the output of ₃ is extracted.

[0047] For example, if the base to the switching voltage Vs of the transistor Q ₅ is a switch element C _1O is not supplied (switching voltage Vs = L level), the transistor Q
₅ are turned ON, the inductance component of the L-C circuit is synthesized Indantakusu coil L _4, L _5. That is, the high frequency band pass characteristic only components of frequencies F ₁ outputted from the signal processing circuit unit B is to pass extraction. Then, the signal of the frequencies F ₁ passing through the filter circuit portion C is derived from the output terminal OUT as an oscillating output signal.

[0048] The switching voltage Vs is supplied (switching voltage Vs = H level), the transistor Q ₅ is turned OFF, thereby, coil L ₄ are no longer contributes to the inductance component of the L-C circuit. That is, the low frequency band pass characteristic properties only component of the frequency f ₂ output from the signal processing circuit unit B is to pass extraction. Then, the signal of the frequency f ₂ that has passed through the filter circuit portion C is derived from the output terminal OUT as an oscillating output signal.

The above operation is as shown in Table 1 below.

[0050]

[Table 1]

[0051] As described above, in the circuit of Figure 2, the L level of the switching voltage Vs is a constant voltage or less (not supplied), the switching diode Di of the circuit A ₁₁ is turned OFF, the fundamental oscillation signal x, the oscillation frequency f ₁ based on the resonance frequency of the initial state set by the resonance circuit a _1. Then, the fundamental oscillation signal x is subjected to frequency multiplication processing in the signal processing circuit section B, and the frequency becomes F ₁ (2 × f ₁ ).
Oscillation output signal of the oscillation frequencies F ₁ is to be derived from the output terminal OUT.

[0052] In the switching voltage Vs is a constant voltage or more H-level, the diode Di of the switching circuit A ₁₁ is turned ON,
When the fundamental oscillation signal x is the strip line L of the resonance circuit section A _1
2, the electrical length becomes shorter, and the oscillation frequency becomes f ₂ (f ₂ > f ₁ ) based on the resonance frequency of which the frequency has been increased. Then, the fundamental oscillation signal x is amplified processed by the signal processing circuit section B, as it is of the oscillation output signal of the frequency f _2, it will be derived from the output terminal OUT.

The voltage-controlled high-frequency oscillator provided with the circuit shown in FIG. 2 is suitable for a dual-mode oscillator for the first frequency in, for example, a receiving circuit of a mobile communication system (GSM system, DCS system) of European specifications. I have. still,
The actually used oscillation frequency is slightly different from the actual carrier frequency, but here the carrier frequency is described as the required oscillation frequency for convenience. For example, G
To support the SM system, the oscillation frequency must be 950M
Hz is required, and an oscillation frequency of 1.8 GHz is required to support the DCS method.

In this case, the switching voltage V in Table 1 described above is used.
The oscillation frequency f ₁ of the fundamental oscillation signal x whose s is L level is 90
0 MHz, the switching voltage Vs is the H level basic oscillation signal x
The oscillation frequency f ₂ to the resonant circuit A ₁₀ set to be 950MHz of. Also, the signal processing circuit section B enters the frequency maintenance / amplification processing mode when the switching voltage Vs is at the H level so that the switching voltage Vs enters the frequency multiplication processing mode at the L level.
At the same time, 1.8 GH at the switching voltage VsL level
The filter circuit section C is set such that the switching voltage Vs has an H level and has a filter characteristic capable of passing around 950 MHz so that the filter characteristic can pass near z.

As a result, when the switching voltage Vs is at the L level, the output terminal OUT provides 1.8 corresponding to the DCS system.
Oscillation output signal of GHz is obtained, when the switching voltage Vs is at the H level so that the oscillation output signal of 950MHz corresponding to the GSM system is obtained from the output terminal OUT _1.

According to this, the oscillation output signals of completely different frequency bands of GSM and DCS can be derived from one control voltage type high frequency oscillation device, and the dual mode type oscillation device becomes highly practical and practical.

Moreover, even if there is no special arithmetic relation between the two types of actually used oscillation frequencies of 950 MHz and 1.8 GHz, it is possible to easily obtain the two required oscillation frequencies. Can be. This is 900M
Based on 950 MHz shifted up from the fundamental oscillation signal of the oscillation frequency of 1 Hz, a multiplication process is performed to 1.8 GHz.
This is because z and an oscillation frequency having a high frequency were created.

The fundamental oscillation signal x output from the oscillation circuit section A is output through a series of processing systems including the signal processing circuit section B and the filter circuit section C regardless of the change in the switching voltage Vs. . That is, the circuit configuration of the voltage-controlled high-frequency oscillator is simplified, and downsizing is achieved. Further, even if the frequency band of the oscillation frequency changes, the oscillation output signal can be derived from one output terminal, so that its use is very simple.

Further, since the transistor Q ₄ in the signal processing circuit B and the coil L ₅ in the filter circuit C can be shared irrespective of the switching voltage H / L, the number of parts can be reduced. And a more compact voltage-controlled high-frequency oscillator.

As described above, in the present invention, the signal processing circuit B
It is important to match the operation mode and the passband characteristic of the filter circuit section C in terms of frequency in conjunction with H / L of the switching voltage Vs. That is, when the signal processing circuit section B is in the frequency multiplication processing operation mode, the pass band frequency of the filter circuit section C becomes higher (corresponding to the frequency of the multiplied wave).
Thus, when the signal processing circuit section B is in the frequency maintaining / amplifying operation mode, the pass band frequency of the filter circuit section C is set to be low (corresponding to the frequency of the fundamental wave).

In the embodiment shown in FIG. 2, the switching voltage V
s is L level, i.e., the oscillation frequency f ₁ of the reference before the resonant circuit A _1O is shifted up, by performing the frequency multiplication process, to form an oscillation output signal of the oscillation frequencies F ₁ of the high frequency band However, for example, the operation of the switching circuit of the resonant circuit a _1O, is set to reverse operation as compared to the operation of FIG. 2, the oscillation frequency f ₂ which is shifted up, performs a frequency multiplication processing, high are it is also possible to form an oscillation output signal of the oscillation frequency F ₂ of the frequency bands.

[0062] Further, in FIG. 2, switching circuit A ₁₁ is the resonance frequency at ON is shifted up, it may be set to the switching circuit A ₁₁ conversely the resonance frequency at ON is shifted down. Furthermore, although there is one output terminal, physically two
It does not matter.

[0063]

According to the present invention, in the voltage controlled high-frequency oscillator, the resonance operation of the resonance circuit section is discretely controlled by the switching voltage, and the frequency of the fundamental oscillation signal output from the oscillation circuit section is changed. The frequency can be switched to at least two types of frequencies f ₁ and f ₂ , and this fundamental oscillation signal is led to an output terminal via one processing system of a fundamental oscillation signal processing circuit section and a filter circuit.

The switching voltage activates the switch element connected to the basic oscillation signal processing circuit section and the switch element connected to the filter circuit section, and the basic oscillation signal processing circuit section operates in the frequency maintenance / amplification processing mode. In the frequency multiplication mode, the filter circuit switches to two frequency passband characteristics.

Therefore, oscillation output signals having different frequency bands can be derived easily and stably.

Further, regardless of the difference in the frequency band of the oscillation output signal, a series of processing systems including an oscillation circuit section for outputting a basic oscillation signal, a basic oscillation signal signal processing circuit section, and a filter circuit section are provided. The components that constitute are more commonly used, the overall circuit is simplified, and downsizing can be achieved.

[Brief description of the drawings]

FIG. 1 is a block diagram of a voltage-controlled high-frequency oscillator according to the present invention.

FIG. 2 is a circuit configuration diagram of the voltage-controlled high-frequency oscillation device of the present invention.

FIG. 3 is a block diagram of a conventional voltage-controlled high-frequency oscillator.

[Explanation of symbols]

A · · · · oscillation circuit unit A ₁ · · · resonance circuit portion A _1O · · · resonant circuit A ₁₁ · · · switching circuit A ₂ · · · negative resistance circuit unit A ₃ · · · amplifying circuit part B · ... Frequency multiplication circuit section _B1O ... Switch element C ... Filter circuit section _C1O ... Switch element x ... Basic oscillation signal

────────────────────────────────────────────────── ─── Continued on the front page (56) References JP-A-7-147551 (JP, A) JP-A-7-226680 (JP, A) JP-A-4-25211 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H03L ⁷ /06-7/23

Claims (1)

(57) [Claims] 1. A control circuit for controlling an oscillation frequency and a switching voltage for switching an oscillation frequency to a different frequency band are provided. The control circuit includes a resonance circuit unit that operates at a predetermined resonance frequency by using both voltages, and outputs a basic oscillation signal. An oscillation circuit unit that performs an amplification process or a multiplication process on a fundamental oscillation signal of the oscillation circuit unit; and a predetermined frequency passband characteristic corresponding to an output frequency of the basic oscillation signal processing circuit unit. The basic oscillation signal processing circuit unit has a switching element that switches between an amplification process and a multiplication process in response to the supply of the switching voltage, and the filter circuit unit performs the switching. A voltage-controlled high-frequency oscillator including a switching element for switching a frequency passband characteristic in accordance with supply of a voltage.