Classifications

• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
  • H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
  • H03B5/30—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator
  • H03B5/32—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator being a piezoelectric resonator
  • H03B5/36—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator being a piezoelectric resonator active element in amplifier being semiconductor device
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03K—PULSE TECHNIQUE
  • H03K3/00—Circuits for generating electric pulses; Monostable, bistable or multistable circuits
  • H03K3/02—Generators characterised by the type of circuit or by the means used for producing pulses
  • H03K3/027—Generators characterised by the type of circuit or by the means used for producing pulses by the use of logic circuits, with internal or external positive feedback
  • H03K3/03—Astable circuits
  • H03K3/0307—Stabilisation of output, e.g. using crystal
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
  • H03B2201/00—Aspects of oscillators relating to varying the frequency of the oscillations
  • H03B2201/02—Varying the frequency of the oscillations by electronic means
  • H03B2201/0208—Varying the frequency of the oscillations by electronic means the means being an element with a variable capacitance, e.g. capacitance diode

Definitions

• the present invention relates to a voltage controlled piezoelectric oscillator capable of linear frequency control.
• QIAJ Quadrature Crystal Industry Association of Japan
• variable capacitance diode is inserted in the oscillation loop as shown in pages 17 to 18 of (2002. 3) on page 17 to 18 of the voltage controlled crystal oscillator, and the variable capacitance diode is By applying a control voltage from the outside to change the capacity of the variable capacity diode, the load capacity of the oscillation loop is changed to change the frequency.
• FIG. 5 is a circuit example of a general voltage control type crystal oscillator disclosed in, for example, Japanese Patent Application Laid-Open No. 09-214250, wherein an inverter element IC1 is used in an oscillation circuit, and the input and output of the inverter element IC1. Insert the high resistance R1 between them to set the operating point to be always at the center.
• a crystal resonator Xtal and variable capacity means in which a capacitor C5 is connected in parallel to a variable capacity diode D1 are inserted in series between the input and output of the inverter element IC1 to form an oscillation loop.
• the variable range can be finely adjusted by connecting the capacitor C5 in parallel to the variable capacitance diode D1.
• capacitors C 1 ⁇ C 2 are inserted between the input and output of the inverter element IC 1 and GND respectively.
• the control voltage Vcont of the external power source is divided by the high resistances R2 and R3 and applied to the force seed of the variable capacitance diode D1.
• the anode of the variable capacitance diode D1 is grounded by the high resistance R4, and the capacitance changes due to the voltage between the force sort anode of the variable capacitance diode D1 and the load capacitance of the oscillation loop changes, so that the oscillation frequency changes. become.
• the variable value range and linearity of the frequency can be finely adjusted by the element values of high resistance R3 and capacitor C5.
• FIG. 6 shows another conventional example used for high frequency oscillation, in which two transistors (TR1, TR2) are connected in cascade in the oscillation circuit. Also, two variable capacitance diodes D1 and D2 are connected in series to prevent the deterioration of the noise characteristics due to the own modulation due to the oscillation level.
• the frequency change from the nominal frequency:! ⁇ is the difference between the equations (1) and (2), and can be expressed by the equation (3).
• Equation (6) is substituted into equation (4), and equation (7) is obtained as a relational equation showing the change in frequency and the variable voltage applied to the variable capacitance diode by the control voltage from the outside.
• Equation (8) which gives a linear frequency change with respect to the variable voltage is shown.
• Equation (9) deforms equation (8) to give a linear frequency change with respect to a variable voltage.
• Fig. 10 shows examples of simulation results of Eqs. (5), (6) and (9).
• variable capacitance C (v) that obtains a straight line is a curve that is 11.8 pF at OV and 7. 5 pF at 5V.
• Figure 11 shows the frequency variation with the variable capacitance C (v) and the combined variable capacitance to obtain a straight line, and the difference between them. A difference of 70 ppm is obtained with a difference of 1 ppm. This value is considered to indicate the compensation limit due to the variable capacitance diode.
• the results shown in FIG. 12 show the capacitance difference between the ideal capacitance variable and the approximate variable capacitance diode, and the frequency deviation due to the capacitance difference.
• FIG. 12 An outline of the contents of FIG. 12 is shown in FIG. That is, when “the ideal capacity change to obtain a straight line” and “variable capacity of the variable capacity diode” according to the log change are optimally selected, It intersects at two points of 1 and 1 ⁇ 2 and shows that the best characteristics can be obtained in the vicinity of the two points, and also indicates the limit of correction! /.
• Patent Document 1 Japanese Patent Application Laid-Open No. 09-214250
• Patent Document 2 Japanese Patent Application Laid-Open No. 10-056330
• the present invention forms an approximate curve for obtaining a plurality of intersections in the same curve, and uses a correction circuit using a variable capacitance diode that performs compensation with higher accuracy. Intended to be configured. Means to solve the problem
• the invention according to claim 1 is characterized in that a first variable capacitance diode and the first variable capacitance diode are used as variable capacitance means constituting a voltage control type piezoelectric oscillator.
• a second capacitor inserted between a first capacitor connected in parallel, the second variable capacitance diode, a force seed of the first variable capacitance diode, and an anode of the second variable capacitance diode.
• a third capacitor inserted and connected between the anode of the first variable capacitance diode and the force sort of the second variable capacitance diode, the external control voltage being the first variable capacitance It is characterized in that the voltage is applied to the diode and the second variable capacitance diode so that the polarities are opposite to each other.
• the invention according to claim 2 is characterized in that a plurality of variable capacity diodes are connected in parallel as the first variable capacity diode.
• the invention according to claim 3 is characterized in that a plurality of variable capacity diodes are connected in parallel as the second variable capacity diode.
• variable capacity diode is further connected in parallel to the first variable capacity diode.
• the invention according to claim 5 is characterized in that a variable capacitance diode is further connected in parallel to the second variable capacitance diode.
• FIG. 1 is a circuit diagram showing a first embodiment of a voltage controlled piezoelectric oscillator according to the present invention. The same parts as those in the conventional circuit shown in FIG. Is omitted to avoid duplication.
• a capacitor C5 is connected in parallel to a variable capacitance diode D1, and a series connection of a crystal resonator Xtal is further inserted into an oscillation loop to obtain V.
• the external control voltage Vcont was divided by the high resistances R2 and R3 and applied to the cathode of the variable capacitance diode D1.
• the capacitance was changed by the voltage change, and the oscillation frequency was controlled.
• the anode of the second variable capacitance diode D2 is connected to the force sort of the first variable capacitance diode D1 via the capacitor C6, and the second variable capacitance
• the power source of the diode D2 is connected to the anode of the first variable capacity diode D1 via the capacitor C7
• the power source of the second variable capacity diode D2 is connected to the reference power source Reg via the high resistance R7. It is connected and pulled up.
• the external control voltage Vcont is subjected to the conventional control via the resistor R2 and at the same time divided by the high resistors R5 and R6 and applied to the anode of the second variable capacitance diode D2.
• the potential between the force sort anode of the variable capacity diode D2 decreases as the control voltage rises, and the variable capacity of the variable capacity diode D2 decreases.
• V aH l ( v ) 0l xe (in
• FIG. 2 shows a second embodiment of the present invention, in which the variable capacitance means according to the present invention is applied to an oscillation circuit in which two transistors most commonly used for reference oscillation of a portable telephone etc. are connected in cascade. It is The configuration and operation of the variable capacitance means are basically the same as the circuit of FIG.
• FIG. 3 shows a third embodiment of the present invention, in which a plurality of variable capacitance diodes connected in parallel as first and second variable capacitance diodes are respectively arranged, and 0 bias is provided by the combined variable capacitance diodes. It is possible to adjust the amount of change with time capacity and control voltage to an appropriate value. That is, by combining variable capacity diodes having a plurality of different characteristics, it is possible to realize an excellent variable capacity means which can not be obtained with a single variable capacity diode.
• FIG. 4 shows a fourth embodiment of the present invention, in which a plurality of variable capacitance diodes connected in series as the first and second variable capacitance diodes are respectively arranged, and combined with the variable capacitance diode.
• a plurality of variable capacitance diodes connected in series as the first and second variable capacitance diodes are respectively arranged, and combined with the variable capacitance diode.
• Figure 15 shows the characteristics of the ideal variable capacitance Cr (V) for obtaining linear variation and the characteristic x3 of the combined capacitance C (v) according to Eq. (15), and the absolute value of the difference between the frequency variation and the linear variation. Further, the combined capacity (V) according to FIG. 15 is represented by equation (16).
• Total variable range 0 to 5 V, within 0.2 ppm deviation from a straight line.
• the straight line and the approximate variable capacitance diode composite capacitance C (V) have three intersection points.
• FIG. 16 is a diagram showing a difference between a linear frequency variable based on Cr and a difference between an ideal variable capacitance Cr (v) and an approximate variable capacitance diode combined capacitance variable C (V) and a frequency variable based on C (V).
• the present invention has been described by exemplifying so-called VCXO.
• the present invention is not limited to this, and may use a piezoelectric vibration device other than a quartz vibrator as a frequency determining element!
• VCXO piezoelectric vibration device other than a quartz vibrator
• FIG. 1 shows an example of the circuit of the present invention.
• FIG. 2 shows an example of the circuit of the present invention.
• FIG. 3 shows an example of the circuit of the present invention.
• FIG. 4 shows an example of the circuit of the present invention.
• FIG. 5 A diagram showing a conventional circuit example.
• FIG. 6 A diagram showing a conventional circuit example.
• FIG. 7 A diagram showing a frequency variable equivalent model.
• FIG. 8 A diagram showing the characteristics of a variable capacitance diode.
• FIG. 9 A diagram showing the characteristics of a variable capacitance diode.
• FIG. 10 A diagram showing simulation results of the conventional circuit.
• FIG. 11 A diagram showing a simulation result of a conventional circuit.
• FIG. 12 A diagram showing a simulation result of a conventional circuit.
• FIG. 13 A variable explanatory diagram of a conventional circuit.
• FIG. 14 A variable explanatory diagram of the circuit of the present invention.
• FIG. 15 is a diagram showing simulation results of the circuit of the present invention.
• FIG. 16 is a diagram showing simulation results of the circuit of the present invention.
• IC1 inverter element R1 to R4 resistance, Xtal crystal oscillator, Dl, D2 variable capacitance diode, C1 to C5 capacitor, TR1, TR2 transistor

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• Chemical & Material Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Oscillators With Electromechanical Resonators (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

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Citations (4)

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• 2004
  • 2004-10-12 JP JP2004297668A patent/JP2006114974A/ja not_active Withdrawn
• 2005
  • 2005-10-12 US US11/665,043 patent/US7719372B2/en not_active Expired - Fee Related
  • 2005-10-12 WO PCT/JP2005/018819 patent/WO2006041107A1/ja not_active Ceased
  • 2005-10-12 CN CN2005800315797A patent/CN101023576B/zh not_active Expired - Fee Related

Patent Citations (4)

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