JP7312388B2 - Adjusting device and oscillator equipped with the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to an adjustment device and an oscillation device having the same.

Conventionally, an oscillator includes an oscillator, an oscillation circuit that oscillates the oscillator, and an adjustment device that compensates for the temperature characteristics of the oscillation frequency of the oscillator.

Patent Literature 1 discloses an adjustment device that inputs a voltage generated by adding a plurality of temperature compensation signals in an adder to a variable capacitance element of an oscillation circuit.

JP 2017-212637 A

The adjustment device, for example, sums a plurality of temperature compensation signals, inputs them to an amplifier, and provides the output of the amplifier to the variable capacitive element. At this time, part of the output of the amplifier is fed back, but if a resistance element is provided in the feedback path of the amplifier, the output of the amplifier is multiplied by the resistance value of the resistance element. The resistance value of the resistive element is subject to large manufacturing errors and changes in temperature, which may cause deterioration in the accuracy of temperature compensation.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide an adjustment device with improved temperature compensation accuracy and an oscillator provided with the same.

An adjusting device according to an aspect of the present invention includes a temperature compensating unit that outputs a current corresponding to temperature, a transconductance amplifier that outputs the current, a resistor unit that converts a current obtained by adding the output of the temperature compensating unit and the output of the transconductance amplifier to a voltage, and a voltage amplifier that amplifies the output of the resistor unit and feeds back the output voltage to the transconductance amplifier, and adjusts the frequency of the oscillator by the output of the voltage amplifier.

ADVANTAGE OF THE INVENTION According to this invention, the adjustment apparatus with which the temperature compensation precision improved, and the oscillator provided with the same can be provided.

1 is a block diagram schematically showing the configuration of an oscillation device according to an embodiment; FIG. It is a block diagram which shows roughly the structure of the adjusting device which concerns on this embodiment. 1 is a circuit diagram schematically showing the configuration of a transconductance amplifier according to an embodiment; FIG. 3 is a circuit diagram schematically showing the configuration of a reference current generator according to the embodiment; FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The drawings of each embodiment are examples, and the dimensions and shapes of each part are schematic, and the technical scope of the present invention should not be construed as being limited to the embodiments.

First, referring to FIG. 1, a schematic configuration of an oscillation device 1 according to an embodiment of the present invention will be described. FIG. 1 is a block diagram schematically showing the configuration of the oscillation device according to this embodiment. The oscillation device 1 includes an oscillator 30 and an adjustment device 100 .

The oscillator 30 is an oscillator that oscillates at a frequency according to the control voltage. The oscillator 30 is, for example, a VCXO (Voltage Controlled Xtal Oscillator). Oscillator 30 includes vibrator 10 and oscillation circuit 20 .

The oscillator 10 is a type of piezoelectric oscillator (Piezoelectric Resonator Unit) that oscillates by a piezoelectric effect, and is a crystal oscillator (Quartz Crystal Resonator Unit) that includes a quartz crystal resonator. A crystal vibrating element is an element that uses a crystal element as a piezoelectric element that is excited by a piezoelectric effect. The crystal piece is, for example, an AT-cut crystal piece. However, the cut angle of the crystal piece is not limited to the AT cut, and for example, the BT cut, GT cut, SC cut, etc. may be applied.

The oscillation frequency of the vibrator 10 fluctuates within the same oscillator 1 according to the temperature of the vibrator 10 . Also, the oscillation frequency of the vibrator 10 has a deviation for each oscillation device 1 . The oscillation device 1 adjusts the oscillation frequency of such a vibrator 10 .

The oscillator circuit 20 is connected to the vibrator 10, oscillates the vibrator 10 at a frequency corresponding to the control voltage, and outputs the oscillated frequency signal to the outside. The oscillation circuit 20 may use the vibrator 10 as a resonator. Also, the oscillation circuit 20 may have a variable capacitance element connected to the vibrator 10 . The variable capacitance element changes its capacitance according to the input control voltage, and changes the oscillation frequency of the vibrator 10 according to the change in capacitance.

The adjustment device 100 adjusts the control voltage of the oscillation circuit 20 according to the temperature of the vibrator 10 . The adjustment device 100 adjusts the control voltage so as to compensate for the temperature characteristics of the vibrator 10 .

Next, a schematic configuration of the adjusting device 100 according to one embodiment of the present invention will be described with reference to FIG. 2 . FIG. 2 is a block diagram schematically showing the configuration of the adjusting device according to this embodiment.

Adjustment device 100 includes reference current generation section 110 , reference voltage generation section 120 , temperature detection section 130 , temperature compensation section 140 , transconductance amplifier 150 , resistance section 160 and voltage amplifier 170 . The adjustment device 100 adjusts the frequency of the oscillator 30 using the voltage Vout (hereinafter referred to as “control voltage Vout”) output from the voltage amplifier 170 according to the temperature of the vibrator 10 .

The reference current generating section 110 generates a reference current Iref and supplies it to each section of the adjustment device 100 . The reference current Iref is supplied to the transconductance amplifier 150, for example. The reference current Iref may be supplied to the outside of the regulating device 100, for example to the oscillation circuit 20. FIG. Further, the reference current generator 110 may be provided outside the adjustment device 100, for example, in the oscillator circuit 20. FIG. In other words, the reference current Iref may be supplied to the adjustment device 100 from the outside.

The reference voltage generation section 120 generates a reference voltage Vin and supplies it to each section of the adjustment device 100 . The reference voltage Vin is supplied to the transconductance amplifier 150 and the temperature compensator 140, for example. The reference voltage Vin may be supplied to the outside of the regulating device 100, for example to the oscillation circuit 20. FIG. Further, the reference voltage generator 120 may be provided outside the adjustment device 100, for example, in the oscillator circuit 20. FIG. In other words, the reference voltage Vin may be supplied to the adjustment device 100 from the outside.

Temperature detector 130 detects the temperature of vibrator 10 . The temperature detection unit 130 generates a voltage Vts (hereinafter referred to as “temperature voltage Vts”) corresponding to the detected temperature of the vibrator 10 . The temperature voltage Vts output from the temperature detector 130 is supplied to the temperature compensator 140, for example. The temperature detection unit 130 may include, for example, at least one temperature sensor that detects the temperature around the vibrator 10 . That is, the temperature detection unit 130 may detect the temperature of the vibrator 10 without contacting the vibrator 10 . Further, the temperature detection unit 130 may detect the temperature of the vibrator 10 by bringing a temperature sensor into contact with the vibrator 10 .

Temperature compensator 140 outputs a current corresponding to temperature. Specifically, the temperature compensation section 140 has a plurality of temperature compensation circuits 141, 142, . . . , 14N. A plurality of temperature compensating circuits 141, 142, . The temperature compensating circuit 141 compares the output of the reference voltage generator 120 (reference voltage Vin) and the output of the temperature detector 130 (temperature voltage Vts) and outputs a current I-1 (hereinafter referred to as "temperature compensated current I-1"). Similarly, the temperature compensating circuits 142-14N respectively compare the reference voltage Vin with the temperature voltage Vts and output temperature compensated currents I-2-IN. The temperature compensator 140 outputs a current Ic that is the sum of the temperature compensated currents I-1 to IN. For example, the temperature-compensated currents I-1 to IN each have signal components with different characteristics, and the current Ic output from the temperature-compensating section 140 changes according to the temperature of the vibrator 10. FIG.

The transconductance amplifier 150 converts the differential voltage between the output of the reference voltage generator 120 (reference voltage Vin) and the output of the voltage amplifier 170 (control voltage Vout) into a current Igm. Specifically, the reference voltage Vin output from the reference voltage generator 120 is input to the non-inverting input terminal (+) of the transconductance amplifier 150 . Also, the control voltage Vout fed back from the voltage amplifier 170 is input to the inverting input terminal (−) of the transconductance amplifier 150 .

The resistance unit 160 is an IV conversion resistance that converts the current Iadd into a voltage Vr and outputs the voltage Vr. A current Iadd input to the resistance unit 160 is a sum of the current Igm output from the transconductance amplifier 150 and the current Ic output from the temperature compensation unit 140 .

The voltage amplifier 170 amplifies the output (voltage Vr) of the resistor section 160 and outputs the control voltage Vout. The control voltage Vout output from the voltage amplifier 170 is input to the oscillation circuit 20 and fed back to the transconductance amplifier 150 . Control voltage Vout can be expressed by the following equation using transconductance Gm of transconductance amplifier 150 , resistance value R of resistor section 160 , and gain Gv of voltage amplifier 170 .

In the above equation, if GvGmR>>1, the control voltage Vout can be expressed by the following equation.

In the above equation, the control voltage Vout is determined by the reference voltage Vin, the transconductance Gm, and the current Ic. In other words, the performance of adjustment device 100 is determined by the performance of reference voltage generator 120 , transconductance amplifier 150 and temperature compensator 140 .

Next, the configuration of transconductance amplifier 150 will be described in more detail with reference to FIG. FIG. 3 is a circuit diagram schematically showing the configuration of the transconductance amplifier according to this embodiment.

The transconductance amplifier 150 includes a transistor M51, a transistor M52, a transistor M53, a transistor M54, and a transistor M55. The transistors M51, M52 and M55 are N-type MOSFETs, and the transistors M53 and M54 are P-type MOSFETs. The transistor M55 corresponds to a tail current source that supplies the tail current Iss.

The output (reference voltage Vin) of the reference voltage generator 120 is input to the gate of the transistor M51. A feedback (control voltage Vout) from the voltage amplifier 170 is input to the gate of the transistor M52. The source of transistor M52 is connected to the source of transistor M51. A tail current Iss is supplied to each source of the transistors M51 and M52. The gate and drain of the transistor M53 are connected together and connected to the drain of the transistor M51. The gate of transistor M54 is connected to the gate of transistor M53, and the drain of transistor M54 is connected to the drain of transistor M52. A node provided between the drain of the transistor M52 and the drain of the transistor M54 is connected to the output terminal, and the drains of the transistors M52 and M54 output current Igm. A power supply voltage Vdd is supplied to the sources of the transistors M53 and M54. A reference current Iref is input to the gate of the transistor M55, and the source of the transistor M55 is grounded. Transistor M55 forms part of a current mirror and copies reference current Iref to output tail current Iss. The drain of transistor M55 provides tail current Iss to the respective sources of transistors M51 and M52.

An analytical expression for the transconductance amplifier 150 shown in FIG. 3 can be expressed by the following expression.

ΔI _D : Igm
ΔV _in : Vin-Vout
μ _n : field effect mobility of each of transistors M51 and M52 C _ox : gate capacitance per unit area of each of transistors M51 and M52 W: channel width of each of transistors M51 and M52 L: channel length of each of transistors M51 and M52 Iss: tail current

Next, with reference to FIG. 4, the configuration of reference current generator 110 will be described in more detail. FIG. 4 is a circuit diagram schematically showing the configuration of the reference current generator according to this embodiment.

The reference current generator 110 includes a transistor M11, a transistor M12, a transistor M13, a transistor M14, and a switched capacitor 115. The transistors M11 and M12 are N-type MOSFETs, and the transistors M13 and M14 are P-type MOSFETs. The switched capacitor 115 functions like a resistive element with a resistance value Rs.

A switched capacitor 115 is connected to the source of the transistor M11. The respective gates of transistors M11 and M12 are connected together and connected to the drain of transistor M12. The source of transistor M12 is grounded. The gate and drain of the transistor M13 are connected together, and are connected to the drain of the transistor M11 and the gate of the transistor M14. The drain of transistor M14 is connected to the drain of transistor M12. A power supply voltage Vdd is supplied to each source of the transistors M13 and M14. A node provided between the drain of the transistor M12 and the drain of the transistor M14 is connected to the output terminal, and the drains of the transistors M12 and M14 output the reference current Iref to the transistor M55 of the transconductance amplifier 150.

A reference current Iref output from the reference current generator 110 shown in FIG. 4 can be expressed by the following equation.

μ _n : Field-effect mobility of each of the transistors M11 to M14 C _ox : Gate capacitance per unit area of each of the transistors M11 to M14 W: Channel width of each of the transistors M11 to M14 L: Channel length of each of the transistors M11 to M14 K: Size ratio between the transistors M11 and M12, that is, K transistors of W/L are arranged in parallel for M11
M11:M12=K(W/L):(W/L)
Rs: equivalent resistance value of switched capacitor 115

Assuming that Iref obtained by the above formula is the tail current Iss, the transconductance Gm of the transconductance amplifier 150 can be expressed by the following formula.

As described above, in this embodiment, the oscillation device 1 includes the adjustment device 100 and the oscillator 30 . Regulating device 100 outputs a control voltage Vout that regulates the frequency of oscillator 30 . The adjustment device 100 includes a temperature compensation section 140 , a transconductance amplifier 150 , a resistance section 160 and a voltage amplifier 170 . The temperature compensator 140 outputs a current Ic corresponding to temperature. Transconductance amplifier 150 outputs current Igm. Resistance unit 160 converts current Iadd, which is the sum of current Ic and current Igm, into voltage Vr. Voltage amplifier 170 amplifies voltage Vr and outputs control voltage Vout. Control voltage Vout is supplied to oscillator 30 and fed back to transconductance amplifier 150 .
According to this, when the transconductance Gm of the transconductance amplifier 150, the resistance value R of the resistor section 160, and the gain Gv of the voltage amplifier 170 satisfy the relationship of GvGmR>>1, the control voltage Vout can be determined by the input to the transconductance amplifier 150, the output of the temperature compensation section 140, and the transconductance Gm of the transconductance amplifier 150. Compared to transistors, capacitors, and the like, resistance elements are subject to large performance deviations due to manufacturing errors and large temperature changes in performance. Since the adjustment device 100 can output the control voltage Vout that does not include the resistance value R as a parameter, it is possible to suppress manufacturing errors in frequency adjustment accuracy and temperature changes. If the transconductance amplifier 150 is configured so that the parameter for determining the transconductance Gm does not include the resistance value, manufacturing errors in frequency adjustment accuracy and temperature changes can be further suppressed.

Some or all of the embodiments of the present invention will be added below, and their effects will be described. In addition, the present invention is not limited to the following additional remarks.

According to one aspect of the present invention, there is provided an adjustment device that includes a temperature compensating unit that outputs a current corresponding to temperature, a transconductance amplifier that outputs the current, a resistor unit that converts a current obtained by adding the output of the temperature compensating unit and the output of the transconductance amplifier to a voltage, and a voltage amplifier that amplifies the output of the resistor unit and feeds back the output voltage to the transconductance amplifier, and adjusts the frequency of the oscillator by the output of the voltage amplifier.
According to this, the manufacturing error and temperature change of the voltage output from the adjustment device are reduced. Therefore, the temperature compensation accuracy of the adjusting device is improved.

As one aspect, it further includes a reference voltage generator that generates a reference voltage, and the transconductance amplifier converts a differential voltage between the output of the reference voltage generator and the output of the voltage amplifier into a current.

As one aspect, the temperature compensating unit further includes a temperature detecting unit that outputs a voltage corresponding to temperature, the temperature compensating unit has a plurality of temperature compensating circuits that compare the output of the reference voltage generating unit and the output of the temperature detecting unit and outputs a current, and the output of the temperature compensating unit is a current obtained by adding the respective outputs of the plurality of temperature compensating circuits.

As one aspect, the transconductance amplifier includes a first transistor whose gate receives the output of the reference voltage generator, a second transistor whose gate receives feedback from the voltage amplifier and outputs a current from its drain, and a tail current source that supplies tail currents to each of the first transistor and the second transistor.

As one aspect, the tail current source further includes a reference current generator that generates a reference current, and the tail current source includes a third transistor having a gate to which the reference current is input and a drain to which the tail current is supplied.

As one aspect, the reference current generator includes a fourth transistor whose gate is connected to the drain and whose drain supplies the reference current, a fifth transistor whose gate is connected to the gate of the fourth transistor, and a switched capacitor connected to the source of the fifth transistor.

As one aspect, an oscillator device comprising: a vibrator; any one of the adjustment devices described above;

The vibrator according to the present embodiment is not limited to a crystal vibrator, and may be a piezoelectric vibrator using any piezoelectric material such as a piezoelectric single crystal, a piezoelectric ceramic, a piezoelectric thin film, or a piezoelectric polymer film as a piezoelectric piece that is excited by the piezoelectric effect.

Embodiments according to the present invention are applicable to any device, such as a timing device, a sound generator, an oscillator, a load sensor, or the like, which performs electromechanical energy conversion by means of a piezoelectric effect, without particular limitation.

As described above, according to one aspect of the present invention, it is possible to provide an adjustment device with improved temperature compensation accuracy and an oscillation device including the adjustment device.

In addition, the embodiment described above is intended to facilitate understanding of the present invention, and is not intended to limit and interpret the present invention. The present invention may be modified/improved without departing from its spirit, and the present invention also includes equivalents thereof. In other words, any embodiment appropriately modified in design by a person skilled in the art is also included in the scope of the present invention as long as it has the features of the present invention. For example, each element provided in each embodiment and its arrangement, material, condition, shape, size, etc. are not limited to those illustrated and can be changed as appropriate. Moreover, each element provided in each embodiment can be combined as long as it is technically possible, and a combination thereof is also included in the scope of the present invention as long as it includes the features of the present invention.

1... Oscillation device,
10... Vibrator,
20 Oscillation circuit,
30 Oscillator,
100... Adjusting device,
110... Reference current generator,
120... Reference voltage generator,
130 ... temperature detection unit,
140 ... temperature compensator,
141 to 141N ... temperature compensation circuit,
150 ... transconductance amplifier,
160... Resistor,
170... voltage amplifier,
M51 to M55, M11 to M14...transistors,
115 ... switched capacitor,

Claims (7)

a temperature compensation unit that outputs a current according to temperature;
a transconductance amplifier that outputs current;
a resistance unit that converts a current obtained by adding the output of the temperature compensation unit and the output of the transconductance amplifier into a voltage;
a voltage amplifier that amplifies the output of the resistance unit and feeds back the output voltage to the transconductance amplifier;
with
A regulating device for regulating the frequency of an oscillator by means of the output of said voltage amplifier. further comprising a reference voltage generator that generates a reference voltage,
The transconductance amplifier converts a differential voltage between the output of the reference voltage generator and the output of the voltage amplifier into a current.
Adjusting device according to claim 1. It further comprises a temperature detection unit that outputs a voltage according to the temperature,
The temperature compensating unit has a plurality of temperature compensating circuits that compare the output of the reference voltage generating unit and the output of the temperature detecting unit and output a current,
The output of the temperature compensating unit is a current obtained by summing the respective outputs of the plurality of temperature compensating circuits.
3. Adjusting device according to claim 2. The transconductance amplifier is
a first transistor having a gate to which the output of the reference voltage generator is input;
a second transistor whose gate receives feedback from the voltage amplifier and whose drain outputs a current;
a tail current source that supplies a tail current to each of the first transistor and the second transistor;
having
4. Adjusting device according to claim 2 or 3. further comprising a reference current generator that generates a reference current;
The tail current source has a third transistor having a gate to which the reference current is input and a drain to which the tail current is supplied.
Adjusting device according to claim 4. The reference current generation unit
a fourth transistor having its gate connected to its drain and having its drain supplying the reference current;
a fifth transistor having a gate connected to the gate of the fourth transistor;
a switched capacitor connected to the source of the fifth transistor;
having
Adjusting device according to claim 5. An adjustment device according to any one of claims 1 to 6;
an oscillator;
an oscillation circuit that oscillates the oscillator at a frequency corresponding to the output of the voltage amplifier;
An oscillating device.

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