JP2006261822A - Oscillation circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To apply an optimum bias voltage suitable for each frequency band to an oscillation transistor, interlocking with switching of an oscillation frequency band. <P>SOLUTION: This circuit is provided with an oscillation transistor 1, resonant circuits 9, 11 each provided so as to correspond to different oscillation frequency bands, and a switching means 12 for selecting any one of the resonant circuits and connecting the selected resonant circuit between a base of the oscillation transistor 1 and a collector thereof. The switching means 12 applies a bias voltage corresponding to the selected resonant circuit to the base of the resonant transistor 1. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an oscillation circuit that can oscillate stably in a plurality of bands.

  As shown in FIG. 3, the conventional oscillation circuit is composed of a voltage control variable tuning circuit unit 31 and an oscillation circuit unit 34. The voltage-controlled variable tuning circuit unit 31 includes a varactor diode 37, a first capacitor 39, a first microstrip line 40 and a second microstrip line 41 connected in series, and a second connected to the connection point thereof. And a switch diode 43 connected in series to the second capacitor 42 and having the cathode grounded, are connected as shown. A control voltage is applied to the cathode of the varactor diode 37 from the tuning control voltage terminal 33 via a resistor.

  The oscillation circuit section 34 has an oscillation transistor 44 to which a predetermined base bias voltage is applied from a power supply terminal 46 and a feedback capacitor is connected, and the collector is grounded in a high frequency manner. The voltage-controlled variable tuning circuit unit 31 is coupled to the base of the oscillation transistor 44, and the oscillation signal is supplied from the emitter of the oscillation transistor 44 to the oscillation signal output terminal.

  A frequency band switching voltage is applied from the frequency band switching voltage supply terminal 36 to the connection point between the second capacitor 42 and the switch diode 43. If the switch diode 43 is turned off by the frequency band switching voltage, the two microstrip lines 40 and 41 function effectively and oscillate in the low frequency band. When the switch diode 43 is turned on, the second microstrip line 41 is disabled and oscillates in the high frequency band (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 09-148888 (FIG. 4)

  In the conventional configuration, the oscillation frequency band is switched by using two microstrip lines or one microstrip line. However, since the bias voltage of the oscillation transistor is the same, the optimum bias voltage for each band is used. The oscillation transistor cannot be driven. Therefore, it was not possible to oscillate stably in any band.

  An object of the present invention is to apply an optimum bias voltage for each frequency band to an oscillation transistor in conjunction with switching of the oscillation frequency band.

  As a first solution, an oscillation transistor, a resonance circuit provided corresponding to a different oscillation frequency band, and one resonance circuit are selected and coupled between the base and collector of the oscillation transistor. Switching means, and a bias voltage corresponding to the selected resonance circuit is applied to the base of the oscillation transistor by the switching means.

  As a second solution, the resonance circuit includes a first resonance circuit and a second resonance circuit, and includes a first resistor and a first resistor for applying a voltage to the base of the oscillation transistor from the power supply side. 2 is provided, and the first resonance circuit is provided in series with the first resistor between the first resistor and the collector of the oscillation transistor, and the second resonance circuit is provided. Provided between the second resistor and the collector of the oscillation transistor in a state of being connected in series to the second resistor, the base of the oscillation transistor is grounded via a third resistor, and the first resistor And the connection point between the first resonance circuit or the connection point between the second resistor and the second resonance circuit are connected to the base of the oscillation circuit by the switching means.

  As a third solving means, the switching means has a first PNP transistor and a second PNP transistor whose collectors are both connected to the base of the oscillation transistor, and the emitter of the first PNP transistor is connected to the emitter of the first PNP transistor. The first resistor is pulled up to the power source by the first resistor, the emitter of the second PNP transistor is pulled up to the power source by the second resistor, and the base of the first PNP transistor is used as the collector of the second PNP transistor. And a switching voltage was applied to the base of the second PNP transistor.

  As a fourth solution, the collector of the oscillation transistor is grounded at a high frequency, a varactor diode is provided for each of the first resonance circuit and the second resonance circuit, and the oscillation frequency is changed for each varactor diode. Control for applying.

  According to the first solution, the oscillation transistor, the resonance circuit provided corresponding to each of the different oscillation frequency bands, and one resonance circuit are selected and coupled between the base and the collector of the oscillation transistor. Switching means, and a bias voltage corresponding to the selected resonance circuit is applied to the base of the oscillation transistor by the switching means, so that the oscillation transistor can be operated with an optimum bias voltage for each oscillation frequency band.

  Further, according to the second solution, the resonance circuit includes the first resonance circuit and the second resonance circuit, and the first resistor and the second resistor for applying a voltage from the power source side to the base of the oscillation transistor. 2 is provided, and the first resonance circuit is provided in series with the first resistor between the first resistor and the collector of the oscillation transistor, and the second resonance circuit is used as the second resistor. Provided between the second resistor and the collector of the oscillation transistor in a state of being connected in series, the base of the oscillation transistor is grounded via the third resistor, and the connection point between the first resistor and the first resonance circuit Alternatively, since the connection point between the second resistor and the second resonance circuit is connected to the base of the oscillation circuit by the switching unit, the switching unit switches the first resonance circuit or the second resonance circuit and switches the bias voltage. 2-band oscillator circuit that enables Kill.

  According to the third solving means, the switching means has a first PNP transistor and a second PNP transistor whose collectors are both connected to the base of the oscillation transistor, and the emitter of the first PNP transistor is the first PNP transistor. And the emitter of the second PNP transistor is pulled up to the power source by the second resistor, the base of the first PNP transistor is connected to the collector of the second PNP transistor, Since the switching voltage is applied to the base of the second PNP transistor, the switching of the resonance circuit and the switching of the bias voltage can be performed simultaneously only by applying the high or low switching voltage to the base of the second PNP transistor.

  Further, according to the fourth solution, the collector of the oscillation transistor is grounded in high frequency, the varactor diode is provided in each of the first resonance circuit and the second resonance circuit, and the oscillation frequency is changed for each varactor diode. Since the control is applied, a two-band voltage controlled oscillation circuit can be configured.

  The basic configuration of the oscillation circuit of the present invention is shown in FIG. Here, an oscillation circuit that oscillates in two bands having different frequency bands will be described. The collector of the oscillation transistor 1 is connected to the power source B and grounded at a high frequency. A feedback capacitor 2 is connected between the base and the emitter, and a feedback capacitor 3 is also connected between the emitter and the collector (ground potential). The emitter is connected to the ground through a series circuit of an emitter bias resistor 4 and an inductance element 5. The emitter of oscillation transistor 1 is coupled to buffer amplifier 6. The base is also connected to the ground via the third resistor 7.

  A first resistor 7 for supplying a bias voltage from the power supply B side to the base of the oscillation transistor 1 is connected in series with the first resonance circuit 9, and the other end of the resonance circuit 9 is grounded (connected to the collector). The second resistor 10 for supplying a bias voltage from the power source B side to the base of the oscillation transistor 1 is connected in series with the second resonance circuit 11, and the other end of the resonance circuit 11 is grounded (connected to the collector). The Either the connection point between the first resistor 8 and the first resonance circuit 9 or the connection point between the second resistor 10 and the second resonance circuit 11 is connected to the base of the oscillation transistor 1 by the switching means 12. Is done.

  According to the above configuration, when the connection point between the first resistor 8 and the first resonance circuit 9 is connected to the base of the oscillation transistor 1, the voltage is divided by the first resistor 8 and the third resistor 7. The applied voltage is applied to the base of the oscillation transistor 1 as a bias voltage. The first resonant circuit 9 is connected between the base and collector of the oscillation transistor 1 to constitute a collector-grounded Colpitts oscillation circuit. The base bias voltage optimum for the oscillation frequency band at this time can be set by the first resistor 8.

  Similarly, when the connection point between the second resistor 10 and the second resonance circuit 11 is connected to the base of the oscillation transistor 1, the voltage divided by the second resistor 10 and the third resistor 7 is A bias voltage is applied to the base of the oscillation transistor 1. The second resonance circuit 11 is connected between the base and collector of the oscillation transistor 1 to constitute a collector-grounded Colpitts oscillation circuit. The base bias voltage optimum for the oscillation frequency band at this time can be set by the second resistor 10.

  The oscillation signal is output from the base of the oscillation transistor 1 and applied to the buffer amplifier 6.

  As described above, the present invention has an advantage that the switching means 12 can simultaneously switch the resonance circuit and the bias voltage.

  FIG. 2 shows a specific circuit. The description of the same configuration as in FIG. 1 is omitted. The collector of the oscillation transistor 1 is grounded at high frequency by a bypass capacitor 13. The first resonant circuit 9 includes a first varactor diode 9a having a cathode grounded and a first inductance element (configured by a strip line) 9b, and the anode of the first varactor diode 9a is coupled to the first resonant circuit 9a. The capacitor 9c is connected in parallel to the first inductance element 9b.

  The second resonant circuit 11 is configured by a series connection circuit of a second varactor diode 11a and a second inductance element (configured by a strip line) 11b. The anode of the second varactor diode 11a is The second inductance element 11b is grounded in a direct current manner.

  A control voltage is applied from the control voltage terminal T to the cathode of the first varactor diode 9a and the cathode of the second varactor diode 11a via the choke inductors 14 and 15, respectively. Therefore, a voltage controlled oscillation circuit in which the oscillation frequency is changed by the control voltage is configured. The control voltage terminal T is grounded by a bypass capacitor 16 at a high frequency.

  The switching means 12 is composed of two PNP transistors 12a and 12b. The collector of the first PNP transistor 12 a and the collector of the second PNP transistor 12 b are both connected to the base of the oscillation transistor 1. The emitter of the first PNP transistor 12 a is connected to the first resistor 8, and the emitter of the second PNP transistor 12 b is connected to the second resistor 10. The first resonance circuit 9 is coupled to the connection point between the emitter of the first PNP transistor 12 a and the first resistor 8 by the coupling capacitor 17, and the second resonance circuit 11 is coupled to the second PNP by the coupling capacitor 18. Coupled to the connection point between the emitter of transistor 12b and second resistor 10. The base of the first PNP transistor 12a is connected to the collector of the second PNP transistor 12b, and a switching voltage is applied to the base of the second PNP transistor 12b.

  In this configuration, when a high switching voltage (the same voltage as the power supply B) is applied to the base of the second PNP transistor 12b, only the first PNP transistor 12a is turned on, and the first resistor 8 and the third resistor 7 is connected, and the first resonance circuit 9 is coupled to the base of the oscillation transistor 1. If a low switching voltage (0 volt) is applied to the base of the second PNP transistor 12b, only the second PNP transistor 12b is turned on, and the second resistor 10 and the third resistor 7 are connected. The second resonance circuit 11 is coupled to the base of the oscillation transistor 1.

  In any case, since the control voltage is applied from the control voltage terminal T to the cathodes of the first varactor diode 9a and the second varactor diode 11a, the oscillation frequency can be changed by changing the control voltage. According to this switching means 12, the resonance circuit and the bias voltage can be switched simultaneously by simply applying a high or low switching voltage to the base of the second PNP transistor 12b.

  Of course, the configuration of the two resonance circuits 9 and 11 is not limited to that shown in FIG. 2, and various modifications can be made. An oscillation circuit other than the grounded collector type can be configured as the oscillation circuit type.

It is a circuit diagram which shows the basic composition of the oscillation circuit of this invention. It is a circuit diagram which shows the specific structure of the oscillation circuit of this invention. It is a circuit diagram which shows the structure of the conventional oscillation circuit.

Explanation of symbols

1: Oscillation transistor 2, 3: Feedback capacitor 4: Emitter bias resistor 5: Inductance element 6: Buffer amplifier 7: Third resistor 8: First resistor 9: First resonance circuit 9a: First varactor diode 9b : First inductance element 9c: coupling capacitor 10: second resistor 11: second resonance circuit 12: switching means 12a: first PNP transistor 12b: second PNP transistor 13, 16: bypass capacitors 14, 15 : Choke inductor 17, 18: Coupling capacitor

Claims (4)

Comprising: an oscillation transistor; a resonance circuit provided corresponding to each of different oscillation frequency bands; and a switching means for selecting one of the resonance circuits and coupling between the base and collector of the oscillation transistor An oscillation circuit, wherein a bias voltage corresponding to the resonance circuit is applied to the base of the oscillation transistor by the switching means. The resonance circuit includes a first resonance circuit and a second resonance circuit, and includes a first resistor and a second resistor for applying a voltage from a power supply side to the base of the oscillation transistor, and the first resistor Is provided between the first resistor and the collector of the oscillation transistor in a state of being connected in series to the first resistor, and the second resonance circuit is connected in series to the second resistor. In this state, the oscillation resistor is provided between the second resistor and the collector of the oscillation transistor, the base of the oscillation transistor is grounded via a third resistor, and the first resistor and the first resonance circuit are 2. The oscillation circuit according to claim 1, wherein a connection point or a connection point between the second resistor and the second resonance circuit is connected to a base of the oscillation circuit by the switching unit. The switching means has a first PNP transistor and a second PNP transistor whose collectors are both connected to the base of the oscillation transistor, and the emitter of the first PNP transistor is pulled up to the power supply by the first resistor. The emitter of the second PNP transistor is pulled up to the power supply by the second resistor, the base of the first PNP transistor is connected to the collector of the second PNP transistor, and the second PNP transistor is connected. The oscillator according to claim 2, wherein a switching voltage is applied to a base of the transistor. The collector of the oscillation transistor is grounded at a high frequency, a varactor diode is provided in each of the first resonance circuit and the second resonance circuit, and control for changing the oscillation frequency is applied to each varactor diode. The oscillation circuit according to any one of claims 1 to 3.

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