Oscillation circuit, oscillation method, and adjustment method for oscillation circuit

Abstract

The present application provides an oscillation circuit, an oscillation method, and an adjustment method of the oscillation circuit. A high-precision oscillation circuit is provided. An oscillation circuit (100) includes an oscillator (20) that generates a first oscillation signal (S XOSC ) by oscillating a resonator (10); and a phase-locked loop circuit (30) that adjusts a ratio of a first frequency (f XOSC ) of the first oscillation signal (S XOSC ) to a second frequency (f VCO ) of a second oscillation signal (S VCO ) output from a voltage-controlled oscillator (35), and controls the oscillator (20) based on an input voltage, i.e., a loop filter voltage (V C ), of the voltage-controlled oscillator (35).

Description

Technical Field

[0001] This disclosure relates to an oscillation circuit, an oscillation method, and an adjustment method for the oscillation circuit. Background Technology

[0002] Previously, it was known that a secondary vibration with a frequency higher than the primary vibration occurred in a crystal oscillator (refer to...). Figure 13 This causes the oscillator circuit used to dampen the oscillator used to make the crystal oscillator oscillate (for example, see Patent Document 1).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2020-136870 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] However, conventional oscillator circuits rely on secondary vibrations, which occur at lower frequencies and sporadically compared to the main vibration, to allow the oscillator to decay. Therefore, to detect secondary vibrations with high accuracy, the frequency determination threshold is adjusted while actually reproducing the secondary vibration for each individual vibration. However, this is difficult because the secondary vibrations occur at low frequencies. Consequently, adjusting the frequency determination threshold for each individual vibration becomes challenging, leading to insufficient detection accuracy for secondary vibrations.

[0008] The purpose of this disclosure, made in view of the above, is to provide a high-precision oscillation circuit.

[0009] Solution for solving the problem

[0010] One embodiment of the oscillation circuit includes: an oscillator that causes a resonator to oscillate to generate a first oscillation signal; and a phase-locked loop circuit that adjusts the ratio of a first frequency of the first oscillation signal to a second frequency of a second oscillation signal output from a voltage-controlled oscillator, and controls the oscillator based on the input voltage of the voltage-controlled oscillator, i.e., the loop filter voltage.

[0011] One embodiment of the oscillation method includes the following steps: an oscillator causes a resonator to oscillate to generate a first oscillation signal; a phase-locked loop circuit adjusts the ratio of a first frequency of the first oscillation signal to a second frequency of a second oscillation signal output from a voltage-controlled oscillator; and the phase-locked loop circuit controls the oscillator according to the input voltage of the voltage-controlled oscillator, i.e., the loop filter voltage.

[0012] One embodiment of the oscillation circuit adjustment method includes an oscillation circuit comprising an oscillator, a phase-locked loop circuit, and a control unit, comprising the following steps: the oscillator oscillates a resonator to generate a first oscillation signal; a first adjustment step in which the control unit adjusts the ratio of a first frequency of the first oscillation signal to a second frequency of a second oscillation signal output from the voltage-controlled oscillator such that the loop filter voltage input to the voltage-controlled oscillator of the phase-locked loop circuit becomes a voltage equivalent to the secondary oscillation; a second adjustment step in which the control unit adjusts a first threshold based on the loop filter voltage adjusted in the first adjustment step; a third adjustment step in which the control unit adjusts the ratio of the first frequency of the first oscillation signal to the second frequency of the second oscillation signal output from the voltage-controlled oscillator such that the loop filter voltage adjusted in the first adjustment step becomes a voltage equivalent to the primary oscillation; and a fourth adjustment step in which the control unit adjusts a second threshold based on the loop filter voltage adjusted in the third adjustment step.

[0013] The effects of the invention

[0014] According to this disclosure, a high-precision oscillation circuit can be provided. Attached Figure Description

[0015] Figure 1 This is a diagram illustrating an example of the structure of the oscillating circuit according to the first embodiment.

[0016] Figure 2 This is a diagram illustrating an example of the structure of the oscillating circuit according to the first embodiment.

[0017] Figure 3A This is a diagram illustrating an example of the relationship between the loop filter voltage and the oscillation frequency of a voltage-controlled oscillator in a phase-locked loop circuit as previously discussed.

[0018] Figure 3B This is a diagram illustrating an example of the relationship between the loop filter voltage and the oscillation frequency of the voltage-controlled oscillator in the phase-locked loop circuit according to the first embodiment.

[0019] Figure 4 This is a timing diagram illustrating an example of the operation of the oscillation circuit according to the first embodiment.

[0020] Figure 5 This is a flowchart illustrating an example of the oscillation method according to the first embodiment.

[0021] Figure 6 This is a diagram illustrating an example of the structure of the oscillation circuit according to the second embodiment.

[0022] Figure 7AThis is a timing diagram illustrating an example of the operation of a previously discussed oscillator circuit.

[0023] Figure 7B This is a timing diagram illustrating an example of the operation of a previously discussed oscillator circuit.

[0024] Figure 8 This is a diagram illustrating an example of the structure of the oscillation circuit according to the third embodiment.

[0025] Figure 9 This is a timing diagram illustrating an example of the operation of the oscillation circuit according to the third embodiment.

[0026] Figure 10 This is a diagram illustrating an example of the structure of the oscillation circuit according to the fourth embodiment.

[0027] Figure 11A This is a diagram illustrating an example of the relationship between the loop filter voltage and the oscillation frequency of the voltage-controlled oscillator in the phase-locked loop circuit according to the fourth embodiment.

[0028] Figure 11B This is a diagram illustrating an example of the relationship between the loop filter voltage and the oscillation frequency of the voltage-controlled oscillator in the phase-locked loop circuit according to the fourth embodiment.

[0029] Figure 12 This is a diagram illustrating an example of the structure of the oscillation circuit according to the fifth embodiment.

[0030] Figure 13 This is a diagram illustrating an example of the impedance characteristics of a crystal oscillator.

[0031] Figure 14 This is a flowchart illustrating an example of an adjustment method for the oscillating circuit according to the first embodiment. Detailed Implementation

[0032] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In principle, the same reference numerals are used to label the same constituent elements, and repeated descriptions are omitted.

[0033] In this specification, "primary vibration equivalent voltage" refers to the loop filter voltage when the resonator exhibits primary vibration. "Secondary vibration equivalent voltage" refers to the loop filter voltage when the resonator exhibits secondary vibration.

[0034] Furthermore, in this specification, "primary vibration mode" refers to the mode in which the oscillation signal of the oscillator coincides with the primary vibration occurring in the resonator. "Secondary vibration mode" refers to the mode in which the oscillator's oscillation signal coincides with the secondary vibration occurring in the resonator. "Power-off mode" refers to the mode in which the oscillator's oscillation signal decays. However, these terms are merely for convenience and should not be interpreted restrictively.

[0035] <First Implementation Method>

[0036] [Oscillator Circuit]

[0037] Reference Figure 1 and Figure 2 An example of the structure of the oscillation circuit 100 according to the first embodiment will be described.

[0038] The oscillation circuit 100 includes a resonator 10, an oscillator 20, a PLL (Phase Locked Loop) circuit 30, a storage unit 40, and an interface unit 50. The phase-locked loop circuit 30 includes a first frequency divider 31, a phase comparator 32, a charge pump 33, an attenuation control circuit 34, a voltage-controlled oscillator 35, and a second frequency divider 36. The oscillation circuit 100 is connected to a control unit 200 located outside the oscillation circuit 100 via input / output terminals SDIO and input terminal SCL. Furthermore, in... Figure 1 In this specification, the case where the control unit 200 is located outside the oscillation circuit 100 is given as an example, but the control unit 200 may also be located inside the oscillation circuit 100. Furthermore, in this specification, the first frequency divider 31 and the second frequency divider 36 are sometimes collectively referred to as frequency divider circuits.

[0039] The resonator 10 is an oscillator that generates a primary vibration known as the C mode or a secondary vibration known as the B mode. For example, it can be an SC-cut crystal oscillator, an AT-cut crystal oscillator, a MEMS (Micro Electro Mechanical Systems) oscillator, or a ceramic oscillator. The resonator 10 is connected to the oscillator 20 via connection terminals X1 and X2. For example, in the case where the resonator 10 is an SC-cut crystal oscillator, the frequency of the secondary vibration is approximately 10% higher than the frequency of the primary vibration.

[0040] Oscillator 20 causes resonator 10 to oscillate, generating an oscillation signal (first oscillation signal) S. XOSC Oscillator 20 will generate the oscillation signal S. XOSC The output is sent to the phase-locked loop circuit 30.

[0041] Furthermore, the oscillator 20 is controlled based on the control signal XO_PD input from the phase-locked loop circuit 30. For example, when the control signal XO_PD input from the phase-locked loop circuit 30 switches from "low voltage" to "high voltage", the oscillator 20 will oscillate the signal S. XOSC Switching from secondary vibration mode to power-off mode (refer to...) Figure 4 ).

[0042] The phase-locked loop circuit 30 adjusts the division ratio M1 of the first frequency divider 31 and the division ratio M2 of the second frequency divider 36 appropriately based on the first memory data stored in the storage unit 40 to control the oscillation signal S. XOSC Frequency (first frequency) f XOSC The multiplication ratio is adjusted. For example, the phase-locked loop circuit 30 adjusts the multiplication ratio to make the oscillation signal S generated by the oscillator 20 more responsive. XOSC frequency f XOSC The oscillation signal (second oscillation signal) S output from the voltage-controlled oscillator 35 VCO Frequency (second frequency) f VCO The ratio is 1:1 or 10:11. Furthermore, the value of the multiplication ratio is not particularly limited; the control unit 200 can adjust the multiplication ratio to any value by appropriately setting the first memory data. In the accompanying drawings, the case where (M1, M2) is (10div, 11div) is described as an example, but the value of the division ratio M1 or division ratio M2 is not particularly limited. The division ratio M1 or division ratio M2 can, for example, be any integer. The division ratio M1 or division ratio M2 can, for example, be a fractional division ratio implemented using a fractional divider.

[0043] The first memory data is used to adjust the oscillation signal S. XOSC frequency f XOSC The adjustment data for the multiplication ratio. The first memory data may be, for example, data representing the division ratio M1 of the first frequency divider 31, or data representing the division ratio M2 of the second frequency divider 36.

[0044] In addition, the phase-locked loop circuit 30 uses the second memory data stored in the storage section 40 to convert the input voltage of the voltage-controlled oscillator 35, i.e., the loop filter voltage V, into the input voltage V of the voltage-controlled oscillator 35. C The voltage V equivalent to the principal oscillation C1 Larger and more powerful than the secondary vibration equivalent voltage V C2 The small voltage, i.e., the first threshold V TH1 (Equivalent voltage of the main oscillation V) C1 <First threshold V TH1 <Equivalent voltage V of secondary vibration C2 The comparison generates a control signal XO_PD for controlling the oscillator 20. Alternatively, the phase-locked loop circuit 30 uses data from the third memory stored in the storage unit 40 to compare the input voltage of the voltage-controlled oscillator 35, i.e., the loop filter voltage V. C The voltage V equivalent to the principal oscillation C1 The small voltage, i.e., the second threshold V TH2 (second threshold V) TH2 <Equivalent voltage V of principal oscillation C1The comparison is performed, thereby generating a control signal XO_PD for controlling oscillator 20. Phase-locked loop circuit 30 outputs the control signal XO_PD to oscillator 20. Additionally, the loop filter voltage V... C First threshold V TH1 Second threshold V TH2 Alternatively, the input signal can be a digital value generated by a digital circuit instead of a voltage. Furthermore, the voltage-controlled oscillator 35 can also be configured as a digitally controlled oscillator that sets the input signal to a digital value instead of a voltage.

[0045] First threshold V TH1 Second threshold V TH2 The value of V is not specifically limited. In this specification, the second threshold V is listed as an example. TH2 <First threshold V TH1 The case was given as an example and explained, but of course it could also be the first threshold V. TH1 <Second threshold V TH2 Additionally, this specification provides examples of the oscillation frequency of the voltage-controlled oscillator 35 relative to the loop filter voltage V. C The case of an increase with the increase of [variable name] is illustrated as an example; however, the oscillation frequency of the voltage-controlled oscillator 35 can also be relative to the loop filter voltage V. C The increase leads to a decrease.

[0046] The second memory data is used to determine whether to attenuate the oscillator 20, that is, whether to reduce the oscillation signal S of the oscillator 20. XOSC Data for determining power-off mode (refer to) Figure 4 The second memory data could, for example, represent the first threshold V. TH1 The second memory data can be data that is pre-entered manually into the control unit 200 and set by the control unit 200 based on that experimental data. Alternatively, the second memory data can also be data set by the control unit 200 using a program for determining the measured value. There are no particular limitations on the method for setting the second memory data.

[0047] The third memory data is the signal S used to determine whether to oscillate the oscillator 20, that is, whether to de-oscillate the oscillator 20. XOSC Data for determining the power outage mode (refer to) Figure 4 The third memory data could, for example, represent the second threshold V. TH2 The third memory data can be data that is pre-entered manually into the control unit 200 and set by the control unit 200 based on that experimental data. Alternatively, the third memory data can also be data set by the control unit 200 using a program for determining the measured value. There are no particular limitations on the method for setting the third memory data.

[0048] For example, in the loop filter voltage V C Greater than the first threshold V TH1 In this case, the phase-locked loop circuit 30 generates a control signal XO_PD to attenuate the oscillator 20, thereby causing the oscillator 20 to attenuate. For example, when the loop filter voltage V... C Less than the second threshold V TH2 In this case, the phase-locked loop circuit 30 generates a control signal XO_PD to make the oscillator 20 oscillate.

[0049] The storage unit 40 may be, for example, a non-volatile memory or a one-time memory. The storage unit 40 stores first memory data, second memory data, and third memory data. The storage unit 40 can store any information used in the operation of the oscillation circuit 100. The storage unit 40 obtains the first memory data, second memory data, and third memory data from the control unit 200 via the interface unit 50. Furthermore, the various data stored in the storage unit 40 are preferably appropriately utilized in accordance with product testing, product shipping, and other appropriate needs.

[0050] An interface unit 50 is disposed between the storage unit 40 and the control unit 200, which is located outside the oscillation circuit 100, and is used to provide a communication interface. The interface unit 50 may be, for example, a serial interface such as an I2C interface or an SPI interface.

[0051] The controller 200 sets first memory data, second memory data, and third memory data. For example, the control unit 200 sets data representing the division ratio M1 of the first frequency divider 31 and data representing the division ratio M2 of the second frequency divider 36. For example, the control unit 200 sets data representing the first threshold V. TH1 Data, representing the second threshold V TH2 The control unit 200 outputs the first memory data, the second memory data, and the third memory data to the storage unit 40 via the interface unit 50.

[0052] The oscillation circuit 100 according to the first embodiment corresponds to the oscillation signal S generated by the oscillator 20. XOSC frequency f XOSC The multiplication ratio is adjusted based on the input voltage of the voltage-controlled oscillator 35, i.e., the loop filter voltage V. C This controls the oscillator 20. Thus, although the input is the main oscillation, it is also possible to virtually generate secondary oscillations that are lower frequency and occur sporadically compared to the main oscillation, for high-precision determination of the loop filter voltage V corresponding to the secondary oscillation. C The voltage threshold can be adjusted, thus enabling a high-precision oscillation circuit 100.

[0053] Phase-locked loop circuit

[0054] Reference Figure 2 An example of the structure of the phase-locked loop circuit 30 according to the first embodiment will be described.

[0055] The first frequency divider 31 uses the data from the first memory to divide the oscillation signal S by a division ratio M1. XOSC Frequency division is performed to generate the frequency-divided signal S. XOSC / DIV Frequency division signal S XOSC / DIV The frequency of the oscillation signal S XOSC frequency f XOSC The frequency is obtained by multiplying by (1 / M1). The first frequency divider 31 divides the frequency signal S... XOSC / DIV The output is sent to phase comparator 32. The first frequency divider 31 can be, for example, a known integer frequency divider, fractional frequency divider, etc. In addition, the division ratio M1 can be any value.

[0056] The voltage-controlled oscillator 35 generates a frequency f that is proportional to the input voltage. VCO The oscillation signal S VCO The voltage-controlled oscillator 35 will generate the oscillation signal S. VCO The output is sent to the second frequency divider 36.

[0057] The second frequency divider 36 uses the data from the first memory to divide the oscillation signal S by a division ratio M2. VCO Frequency division is performed to generate the frequency-divided signal S. VCO / DIV Frequency division signal S VCO / DIV The frequency of the oscillation signal S VCO frequency f VCO The frequency is obtained by multiplying by (1 / M²). The second frequency divider 36 divides the frequency signal S... VCO / DIV The output is sent to phase comparator 32. The second frequency divider 36 can be, for example, a known integer frequency divider, fractional frequency divider, etc. In addition, the division ratio M2 can be any value.

[0058] Phase comparator 32 takes the frequency division signal S input from the first frequency divider 31 as input. XOSC / DIV The phase of the signal is the same as the divided signal S input from the second frequency divider 36. VCO / DIV The phases are compared, and a phase comparison signal S corresponding to the phase difference is generated. COM (For example, a pulsed UP signal, a pulsed DOWN signal). Phase comparator 32 compares the phase signal S. COM The output is sent to charge pump 33. Phase comparator 32 can be, for example, a known mixer, XOR detector, TDC (Time to Digital Converter), etc.

[0059] The charge pump 33 is based on the phase comparison signal S input from the phase comparator 32. COMA charge pump current is generated at node 33N for charging or discharging. The charge pump 33 may be composed of, for example, a constant current source 331a, a switching transistor 332a, a switching transistor 332b, a constant current source 331b, etc.

[0060] The attenuation control circuit 34 detects the input voltage of the voltage-controlled oscillator 35, i.e., the loop filter voltage V. C Based on the loop filter voltage V C The control signal XO_PD for controlling the oscillator 20 is generated using data from the second and third memory. The attenuation control circuit 34 outputs the control signal XO_PD to the oscillator 20.

[0061] The attenuation control circuit 34 can be composed of, for example, comparator 341, comparator 342, SR latch circuit 343, etc.

[0062] Comparator 341 converts the loop filter voltage V C With the first threshold V TH1 The comparison is performed, and the comparison result is output to the set terminal of the SR latch circuit 343. For example, comparator 341 sets the loop filter voltage V. C Greater than the first threshold V TH1 A high-level signal is generated under the condition that the loop filter voltage V C The first threshold V TH1 A low-level signal is generated under the following conditions.

[0063] Comparator 342 converts the loop filter voltage V C With the second threshold V TH2 The comparison is performed, and the comparison result is output to the reset terminal of the SR latch circuit 343. For example, comparator 342 resets the loop filter voltage V. C The second threshold V TH2 Under the above conditions, a high-level signal is generated, and the loop filter voltage V... C Less than the second threshold V TH2 A low-level signal is generated under these conditions.

[0064] The SR latch circuit 343 generates a control signal XO_PD based on the comparison results input from comparator 341 and comparator 342. For example, the SR latch circuit 343 acquires the loop filter voltage V... C Greater than the first threshold V TH1 In the case of this comparison result, a control signal XO_PD is generated to attenuate the oscillator 20. For example, the SR latch circuit 343 acquires the loop filter voltage V C Less than the second threshold V TH2Based on this comparison result, a control signal XO_PD is generated to make the oscillator 20 oscillate.

[0065] Here, refer to Figure 3A and Figure 3B The loop filter voltage V when the resonator 10 is an SC-cut crystal oscillator C [V] and the frequency f of the voltage-controlled oscillator VCO The relationship of [Hz] will be explained.

[0066] Figure 3A This illustrates the inability to handle oscillating signals S as previously discussed. XOSC frequency f XOSC The loop filter voltage V in the phase-locked loop circuit 30', which adjusts the multiplication ratio, is... C [V] and the oscillation signal S output from the voltage-controlled oscillator VCO frequency f VCO The relationship of [Hz].

[0067] Figure 3B This embodiment illustrates the capability to process oscillation signal S. XOSC frequency f XOSC The loop filter voltage V in the phase-locked loop circuit 30, whose multiplication ratio is adjusted, is... C [V] and the oscillation signal S output from the voltage-controlled oscillator VCO frequency f VCO The relationship between [Hz].

[0068] according to Figure 3A It is known that the frequency multiplication ratio of the previously involved phase-locked loop circuit 30' is fixed at 1. Therefore, in order to make the loop filter voltage V... C The equivalent voltage V of the main vibration C1 Frequency f VCO With the frequency f of the main vibration mode XOSC For consistency, resonator 10 must be in a state of dominant oscillation, in order to ensure the loop filter voltage V C The equivalent voltage V of the secondary vibration C2 Frequency f VCO The frequency of the secondary vibration mode is 1.1×f XOSC For this to be consistent, resonator 10 must be in a state of secondary vibration.

[0069] On the other hand, according to Figure 3B As can be seen, the phase-locked loop circuit 30 involved in this embodiment can switch the frequency multiplication ratio to 1 or 1.1, so regardless of the loop filter voltage V C The equivalent voltage V of the main vibration C1 Frequency f VCO With the frequency f of the main vibration modeXOSC When they are consistent, it is still at the loop filter voltage V C The equivalent voltage V of the secondary vibration C2 Frequency f VCO The frequency of the secondary vibration mode is 1.1×f XOSC When they are in sync, the resonator 10 can be in a state of main oscillation.

[0070] As described above, the phase-locked loop circuit 30 of the oscillation circuit 100 involved in this embodiment corresponds to the oscillation signal S. XOSC frequency f XOSC The multiplication ratio is adjusted, and the frequency is detected to control the decay of the oscillator 20. Therefore, even without waiting for secondary vibrations that occur sporadically and at a lower frequency than the main vibration, as in conventional oscillator circuits, a state as if the resonator 10 were experiencing secondary vibrations can be virtually reproduced, and the oscillator 20 can be appropriately controlled. Thus, a high-precision oscillator circuit 100 can be achieved.

[0071] (Time series diagram)

[0072] Reference Figure 4 The timing diagram shown illustrates an example of the operation of the oscillation circuit 100 according to the first embodiment.

[0073] During the period from time t0 to time t1, the attenuation control circuit 34 detects the loop filter voltage V. C The voltage rises, maintaining the control signal XO_PD at a "low voltage". The oscillation signal S of oscillator 20... XOSC It is a secondary vibration mode.

[0074] At time t1, the attenuation control circuit 34 detects the loop filter voltage V. C Compared to the first threshold V TH1 (Equivalent voltage of the main oscillation V) C1 <First threshold V TH1 <Equivalent voltage V of secondary vibration C2 The large voltage switches the control signal XO_PD from "low voltage" to "high voltage". The oscillation signal S of oscillator 20... XOSC The vibration mode changed to the power-off mode.

[0075] During the period from time t1 to time t2, the attenuation control circuit 34 detects the loop filter voltage V. C The voltage drops, maintaining the control signal XO_PD at a "high voltage". The oscillation signal S of oscillator 20... XOSC It is in power-off mode.

[0076] At time t2, the attenuation control circuit 34 detects the loop filter voltage V. C Compared to the second threshold V TH2(second threshold V) TH2 <Equivalent voltage V of principal oscillation C1 The small value switches the control signal XO_PD from "high voltage" to "low voltage". The oscillation signal S of oscillator 20... XOSC The power outage mode has been deactivated.

[0077] During the period from time t2 to time t3, the attenuation control circuit 34 detects the loop filter voltage V. C The voltage rises, maintaining the control signal XO_PD at a "low voltage". The oscillation signal S of oscillator 20... XOSC It is a secondary vibration mode.

[0078] At time t3, the loop filter voltage V was detected. C Compared to the first threshold V TH1 The large voltage switches the control signal XO_PD from "low voltage" to "high voltage". The oscillation signal S of oscillator 20... XOSC The vibration mode changed to the power-off mode.

[0079] During the period from time t3 to time t4, the attenuation control circuit 34 detects the loop filter voltage V. C The voltage drops, maintaining the control signal XO_PD at a "high voltage". The oscillation signal S of oscillator 20... XOSC It is in power-off mode.

[0080] At time t4, the attenuation control circuit 34 detects the loop filter voltage V. C Compared to the second threshold V TH2 The small value switches the control signal XO_PD from "high voltage" to "low voltage". The oscillation signal S of oscillator 20... XOSC The power outage mode has been deactivated.

[0081] After time t4, the attenuation control circuit 34 detects the loop filter voltage V. C The convergence of the dominant oscillation is equivalent to the voltage V. C1 The control signal XO_PD is maintained at a "low voltage". The oscillation signal S of oscillator 20... XOSC It is the main vibration mode.

[0082] As described above, the phase-locked loop circuit 30 repeatedly causes the oscillation signal S of the oscillator 20 to... XOSC For power-off mode, and to release the oscillation signal S of oscillator 20 XOSC The power-off mode continues until the loop filter voltage V... C The convergence of the dominant oscillation is equivalent to the voltage V. C1 Thus, even when using a relatively inexpensive resonator that is prone to causing secondary vibration modes, it is possible to achieve an oscillation circuit 100 that can stably maintain oscillations in the primary vibration mode.

[0083] (Operation of the oscillation circuit)

[0084] Reference Figure 5 An example of an oscillation method of the oscillation circuit 100 according to the first embodiment will be described.

[0085] In step S101, the oscillation circuit 100 causes the resonator 10 to oscillate, thereby generating an oscillation signal S. XOSC .

[0086] In step S102, the oscillation circuit 100 adjusts the oscillation signal S generated by the oscillator 20. XOSC frequency f XOSC With the oscillation signal S output from the voltage-controlled oscillator 35 VCO frequency f VCO The ratio is adjusted. Furthermore, it can be said that the oscillation circuit 100 is in standby mode until the phase-locked loop circuit 30 completes its phase-locking operation and the loop filter voltage V... C It converges to a fixed value.

[0087] In step S103, the oscillation circuit 100 determines the loop filter voltage V. C Is it greater than the first threshold V? TH1 At the loop filter voltage V C Greater than the first threshold V TH1 In the case of (step S103 → Yes), the oscillation circuit 100 performs the processing of step S104. Under the loop filter voltage V... C The first threshold V TH1 In the following cases (step S103 → No), the oscillation circuit 100 performs the processing of step S105.

[0088] In step S104, the oscillation circuit 100 attenuates the oscillator 20. The oscillation signal S of the oscillator 20... XOSC Switch to power-off mode.

[0089] In step S105, the oscillation circuit 100 determines the loop filter voltage V. C Whether it converges to the main oscillation equivalent voltage V C1 At the loop filter voltage V C The convergence of the dominant oscillation is equivalent to the voltage V. C1 In the case of (step S105 → Yes), the oscillation circuit 100 ends the process. The loop filter voltage V... C The voltage V of the non-convergent dominant oscillation is equivalent to... C1 If the condition is not met (step S105 → No), the oscillation circuit 100 performs step S103 again. Here, it is determined that the loop filter voltage V is... C The equivalent voltage V of the main vibration C1The condition is that the loop filter voltage V C The first threshold V TH1 The following is the second threshold V TH2 above.

[0090] In step S106, the oscillation circuit 100 determines the loop filter voltage V. C Is it less than the second threshold V? TH2 At the loop filter voltage V C Less than the second threshold V TH2 In the case of (step S106 → Yes), the oscillation circuit 100 performs the processing of step S107. Under the loop filter voltage V... C The second threshold V TH2 In the above case (step S106 → No), the oscillation circuit 100 continues to process step S104.

[0091] In step S107, the oscillation circuit 100 causes the oscillator 20 to oscillate. The oscillation signal S of the oscillator 20... XOSC The power-off mode is deactivated. Furthermore, in the event of a secondary vibration mode, the system can transition to the primary vibration mode by repeating the cycle of steps S103 → S104 → S106 → S107 → S103 → ...

[0092] (Adjustment method for secondary vibration / primary vibration determination threshold)

[0093] Reference Figure 14 An example of the adjustment method of the oscillation circuit 100 according to the first embodiment will be described.

[0094] In step S201, the oscillation circuit 100 (e.g., oscillator 20) causes the resonator 10 to oscillate, thereby generating an oscillation signal S. XOSC .

[0095] In step S202, the oscillation circuit 100 (e.g., the control unit 200) adjusts the frequency multiplication ratio of the phase-locked loop circuit 30 when the oscillator 20 is performing main oscillation, so that the loop filter voltage V generated when the oscillator 20 is performing secondary oscillation and the frequency multiplication ratio of the phase-locked loop circuit 30 is 1:1 is generated. C1 (First adjustment step). For example, the frequency multiplication ratio can be 1:1.

[0096] In step S203, the oscillation circuit 100 (e.g., the control unit 200) uses the loop filter voltage V obtained in step S202. C1 The first threshold V is adjusted in a manner that allows for the detection of secondary vibrations. TH1(Second adjustment step). For example, given the characteristic that the oscillation frequency of the voltage-controlled oscillator 35 increases monotonically relative to the loop filter voltage, the first threshold V can be adjusted. TH1 Adjust to loop filter voltage V C1 The following will be the loop filter voltage V. C1 Is it the first threshold V? TH1 The above judgment signals are used as secondary vibration detection signals.

[0097] In step S204, the oscillation circuit 100 (e.g., control unit 200) uses the loop filter voltage V during the main vibration oscillation of the oscillator 20. C2 The frequency multiplication ratio of the phase-locked loop circuit 30 is adjusted in a manner that allows for the detection of oscillation convergence during the main vibration (third adjustment step). For example, the frequency multiplication ratio can be 1:1.

[0098] In step S205, the oscillation circuit 100 (e.g., the control unit 200) uses the loop filter voltage V obtained in step S204. C2 The second threshold V is adjusted in a manner that allows for the detection of convergent dominant oscillations. TH2 (Fourth adjustment step). For example, given the characteristic that the oscillation frequency of the voltage-controlled oscillator 35 increases monotonically relative to the loop filter voltage, the second threshold V can be adjusted. TH2 Adjust to loop filter voltage V C2 The following will be the loop filter voltage V. C2 Does it converge to the second threshold V? TH2 The above judgment signals are used as the main vibration convergence detection signals.

[0099] As described above, by applying the oscillation method according to the first embodiment, a high-precision oscillation circuit 100 can be achieved. Furthermore, in a conventional resonator, relative to the frequency f... OSC The fundamental oscillation mode contains harmonic oscillation modes, the frequency of which is the frequency f of the fundamental oscillation mode. OSC Integer multiples of M f OSC (M is an integer greater than 2). For example, if (primary, secondary) = (1 f OSC ,2 f OSC ), (Main, Sub) = (2 f OSC 3 f OSC If the frequency of the secondary vibration mode is higher than the frequency of the primary vibration mode, then it is used as the first threshold V. TH1 Second threshold V TH2The frequency division ratios M1 and M2 can be optimized to suppress secondary vibrations. For example, in (primary, secondary) = (1... f OSC ,2 f OSC In the case of [missing information], by selecting the division ratio M1 as 1 and the division ratio M2 as 2, even if the resonator oscillates in the main vibration mode, the loop filter voltage can be made to be equivalent to the voltage V in the secondary vibration mode. C1 Therefore, the first threshold V can be adjusted with high precision. TH1 Furthermore, by selecting a division ratio M1 of 1 and a division ratio M2 of 1, the loop filter voltage can be made equivalent to the voltage V of the dominant vibration mode. C2 Therefore, the second threshold V can be... TH2 Adjust to the optimal value.

[0100] <Second Implementation Method>

[0101] Reference Figure 6 , Figure 7A as well as Figure 7B An example of the structure of the oscillation circuit 100A according to the second embodiment will be described.

[0102] The difference between the oscillation circuit 100A in the second embodiment and the oscillation circuit 100 in the first embodiment is that the oscillation circuit 100 in the first embodiment cannot adjust the charge pump current, while the oscillation circuit 100A in the second embodiment can adjust the charge pump current. Furthermore, the other structures are the same as those in the oscillation circuit 100 in the first embodiment, so repeated descriptions are omitted.

[0103] The oscillation circuit 100A includes a resonator 10, an oscillator 20, a phase-locked loop circuit 30A, a storage unit 40A, and an interface unit 50. The phase-locked loop circuit 30A includes a first frequency divider 31, a phase comparator 32, a charge pump 33A, an attenuation control circuit 34, a voltage-controlled oscillator 35, and a second frequency divider 36.

[0104] The charge pump 33A uses data stored in the fourth memory in the storage unit 40A to appropriately adjust the charge pump current, thereby affecting the loop filter voltage V. C Rise time or loop filter voltage V C The descent time was adjusted.

[0105] The fourth memory data is used for the loop filter voltage V C Rise time or loop filter voltage V CThe adjustment data is used to adjust the fall time. The fourth memory data can be, for example, digital input data input to a switch controlling the on / off state of constant current source 331a, digital input data input to a switch controlling the on / off state of constant current source 331b, or digital-to-analog converter input data for generating the bias voltage of the transistor. Furthermore, the fourth memory data is arbitrarily set by a control unit 200 located outside the oscillation circuit 100.

[0106] For example, such as Figure 7A As shown, when the charge pump current is greater than the optimal value (e.g., around 1mA), the loop filter voltage V... C Rise time or loop filter voltage V C The descent time becomes very short. In this case, the control signal XO_PD maintains a "high voltage" for a duration T. X1 (For example, around 100 μs) becomes very short, so the oscillation signal S XOSC Unable to escape the secondary vibration mode. To avoid this state, charge pump 33A uses fourth memory data to adjust the charge pump current, so that the loop filter voltage V... C Rise time or loop filter voltage V C The descent time has become longer.

[0107] For example, such as Figure 7B As shown, when the charge pump current is less than the optimal value (e.g., around 0.1 μA), the loop filter voltage V... C Rise time or loop filter voltage V C The descent time becomes very long. In this case, the control signal XO_PD remains "high voltage" for a duration T. X2 (For example, around 1 second) becomes very long, and the oscillation signal S XOSC Convergence time T from power-off mode to main vibration mode X3 (For example, around 0.5s) also becomes very long. To avoid this state, charge pump 33A uses fourth memory data to adjust the charge pump current, making the loop filter voltage V... C Rise time or loop filter voltage V C The descent time has become shorter.

[0108] In addition to storing first memory data, second memory data, and third memory data, the storage unit 40A also stores fourth memory data. The storage unit 40A can store any information used in the operation of the oscillation circuit 100A. The storage unit 40A obtains the first memory data, second memory data, third memory data, and fourth memory data from the control unit 200 via the interface unit 50.

[0109] The oscillation circuit 100A involved in the second embodiment controls the oscillation signal S generated by the oscillator 20. XOSC frequency f XOSC The multiplication ratio is adjusted based on the input voltage of the voltage-controlled oscillator 35, i.e., the loop filter voltage V. C This controls the oscillator 20. Thus, a high-precision oscillator circuit 100A can be achieved.

[0110] Furthermore, in the second embodiment, the charge pump 33A of the oscillation circuit 100A uses fourth memory data to adjust the charge pump current, thereby enabling the loop filter voltage V to be adjusted. C Rise time or loop filter voltage V C The time of descent, in other words, the time of descent. Figure 7A and Figure 7B The loop filter voltage V shown C The slope dVc / dt[V / s] of [V] on the curve is varied to appropriately control the decay time of the oscillator 20. Thus, an oscillation signal S can be achieved. XOSC It can break away from the secondary vibration mode and shorten the loop filter voltage V by a large margin. C From the first threshold V TH1 The convergence of the dominant oscillation is equivalent to the voltage V. C1 An oscillation circuit of 100A for the specified time.

[0111] <Third Implementation Method>

[0112] Reference Figure 8 and Figure 9 An example of the structure of the oscillation circuit 100B according to the third embodiment will be described.

[0113] The difference between the oscillation circuit 100B according to the third embodiment and the oscillation circuit 100 according to the first embodiment is that the oscillation circuit 100 according to the first embodiment does not have a lock detection circuit and a power-off timer circuit, while the oscillation circuit 100B according to the third embodiment has a lock detection circuit 37 and a power-off timer circuit 38. Other than that, the structure is the same as that of the oscillation circuit 100 according to the first embodiment, so repeated descriptions are omitted.

[0114] The oscillation circuit 100B includes a resonator 10, an oscillator 20, a phase-locked loop circuit 30B, a storage unit 40B, and an interface unit 50. The phase-locked loop circuit 30B includes a first frequency divider 31, a phase comparator 32, a charge pump 33, an attenuation control circuit 34, a voltage-controlled oscillator 35, a second frequency divider 36, a lock-in detection circuit 37, and a power-off timer circuit 38.

[0115] Lock-in detection circuit 37 is based on the input signal (the aforementioned frequency division signal S) input to phase comparator 32. XOSC / DIV and frequency division signal S VCO / DIV To determine whether the phase-locked loop circuit 30B is in a locked state, that is, to determine whether the phase-locked loop circuit 30B detects an oscillation signal S. XOSC The system stabilizes in its main vibration mode and generates a detection signal LOCK. The lock detection circuit 37 outputs the detection signal LOCK to the power-off timer circuit 38. The structure of the lock detection circuit 37 is not particularly limited and can adopt a known structure.

[0116] For example, if the lock detection circuit 37 determines that the phase-locked loop circuit 30B is in a locked state, it generates a high-level signal as the detection signal LOCK and outputs it to the power-off timer circuit 38. Alternatively, if the lock detection circuit 37 determines that the phase-locked loop circuit 30B is not in a locked state, it generates a low-level signal as the detection signal LOCK and outputs it to the power-off timer circuit 38.

[0117] The power-off timer circuit 38 uses data from the fifth memory to generate a control signal PD_PLL for controlling the phase-locked loop circuit 30B, based on the detection signal LOCK input from the lock detection circuit 37.

[0118] The fifth memory data is used to determine whether to de-energize the phase-locked loop circuit 30B. For example, when the power supply voltage is set to VDD, the fifth memory data could be a voltage greater than 0.1V and less than VDD-0.1V, i.e., the third threshold V. TH3 (0.1V < third threshold V) TH3 The data is <VDD-0.1V). In addition, the fifth memory data is arbitrarily set by the control unit 200 located outside the oscillation circuit 100.

[0119] The structure of the power-off timer circuit 38 is not particularly limited. For example, it can be composed of a constant current source 381, a switching transistor 382, ​​a comparator 383, etc.

[0120] For example, when the power-off timer circuit 38 receives a high-level signal from the lockout detection circuit 37, it turns on the switching transistor 382, ​​allowing a specified current to flow from the constant current source 381 into the capacitor C3, causing the voltage of the capacitor C3 to gradually rise. This generates a ramp voltage V at the positive terminal of the comparator 383. ramp The comparator 383 converts the ramp voltage V at the positive terminal... ramp The third threshold V at the negative terminal TH3 The comparison is performed, and the control signal PD_PLL is generated based on the comparison result.

[0121] Specifically, at the ramp voltage V ramp Greater than the third threshold V TH3 In the event of a power-off, the power-off timer circuit 38 generates a high-level signal as the control signal PD_PLL, and de-energizes the phase-locked loop circuit 30B. Alternatively, under the ramp voltage V ramp The third threshold V TH3 In the following situations, the power-off timer circuit 38 generates a low-level signal as the control signal PD_PLL to prevent the phase-locked loop circuit 30B from being powered off.

[0122] For example, when the power-off timer circuit 38 receives a low-level signal from the lock-up detection circuit 37, it turns off the switching transistor 382, ​​preventing the voltage of capacitor C3 from rising. The power-off timer circuit 38 generates a low-level signal as the control signal PD_PLL to prevent the phase-locked loop circuit 30B from being powered off.

[0123] In addition to storing first memory data, second memory data, and third memory data, storage unit 40B also stores fifth memory data. Storage unit 40B can store any information used in the operation of oscillation circuit 100B. Storage unit 40B obtains the first memory data, second memory data, third memory data, and fifth memory data from control unit 200 via interface unit 50.

[0124] The oscillation circuit 100B according to the third embodiment controls the oscillation signal S generated by the oscillator 20. XOSC frequency f XOSC The multiplication ratio is adjusted based on the input voltage of the voltage-controlled oscillator 35, i.e., the loop filter voltage V. C This controls the oscillator 20. Thus, a high-precision oscillator circuit 100B can be achieved.

[0125] Furthermore, in the third embodiment, the oscillation circuit 100B de-energizes the phase-locked loop circuit 30B after detecting that it is in a locked state. That is, the oscillation circuit 100B in the third embodiment de-energizes the phase-locked loop circuit 30B in response to the oscillation signal S. XOSC Once the main vibration mode is established and stabilized, the phase-locked loop circuit 30B is de-energized. This suppresses the operating noise of the phase-locked loop circuit 30B from circulating back into the noise-sensitive oscillation circuit 100B via the power supply and components within the circuit. Furthermore, it prevents the degradation of noise characteristics, achieving a highly stable oscillation circuit 100B.

[0126] <Fourth Implementation Method>

[0127] Reference Figure 10 , Figure 11A as well as Figure 11B An example of the structure of the oscillation circuit 100C according to the fourth embodiment will be described.

[0128] The difference between the oscillation circuit 100C according to the fourth embodiment and the oscillation circuit 100B according to the third embodiment is that the attenuation control circuit 34 in the oscillation circuit 100B according to the third embodiment does not have a temperature sensor, while the attenuation control circuit 34C in the oscillation circuit 100C according to the fourth embodiment does have a temperature sensor 344. Furthermore, the other structures are the same as those in the oscillation circuit 100B according to the third embodiment, therefore, repeated descriptions are omitted.

[0129] The oscillation circuit 100C includes a resonator 10, an oscillator 20, a phase-locked loop circuit 30C, a storage unit 40B, and an interface unit 50. The phase-locked loop circuit 30C includes a first frequency divider 31, a phase comparator 32, a charge pump 33, an attenuation control circuit 34C, a voltage-controlled oscillator 35, a second frequency divider 36, a lock-in detection circuit 37, and a power-off timer circuit 38.

[0130] Attenuation control circuit 34C detects loop filter voltage V C Based on the loop filter voltage V C In addition to using data from the second and third memory, the sensor signal input from the temperature sensor 344 is also used to generate a control signal XO_PD for controlling the oscillator 20. The attenuation control circuit 34C outputs the control signal XO_PD to the oscillator 20.

[0131] The attenuation control circuit 34C can be composed of, for example, comparator 341, comparator 342, SR latch circuit 343, temperature sensor 344, etc.

[0132] Temperature sensor 344 measures the temperature of phase-locked loop circuit 30C and generates a sensor signal as the measurement result. Temperature sensor 344 outputs the sensor signal to comparator 341. For example, if temperature sensor 344 measures a low temperature (e.g., around -40°C), it outputs a sensor signal indicating the low temperature to comparator 341. Similarly, if temperature sensor 344 measures a room temperature (e.g., around 25°C), it outputs a sensor signal indicating the room temperature to comparator 341. Finally, if temperature sensor 344 measures a high temperature (e.g., around 105°C), it outputs a sensor signal indicating the high temperature to comparator 341.

[0133] Comparator 341 uses the sensor signal input from temperature sensor 344 to convert the loop filter voltage V C With the first threshold V TH1 The comparison is performed, and the comparison result is output to the set terminal of the SR latch circuit 343.

[0134] like Figure 11AAs shown, the first threshold V TH1 Its properties vary with temperature. First threshold V TH1 According to the first threshold V at low temperature TH1 _LT, the first threshold V at room temperature TH1 _RT, the first threshold V at high temperature TH1 The order of _HT increases. First threshold V TH1 The temperature characteristics can be set by the control unit 200 based on the sensor signal from the temperature sensor 344. The control unit 200 can easily obtain the first threshold voltage V by amplifying the voltage of the temperature sensor 344 with optimal gain, for example, using a known amplifier. TH1 Temperature characteristics. Furthermore, the first threshold V TH1 The temperature characteristics are not limited to a first-degree polynomial; they can also be N-degree polynomials (N being an integer greater than 2). The higher the degree, the more precise the threshold control of temperature changes. Furthermore, the first threshold V... TH1 The temperature characteristics are not limited to first-order or Nth-order polynomials; they can also be continuous functions such as trigonometric functions, exponential functions, logarithmic functions, and sigmoid functions.

[0135] like Figure 11B As shown, the principal oscillation is equivalent to the voltage V. C1 The voltage V equivalent to the secondary vibration C2 Its characteristics also vary with temperature. The principal oscillation corresponds to the voltage V. C1 According to the principal vibration equivalent voltage V at low temperature C1 _LT, equivalent voltage of principal oscillation at room temperature V C1 _RT, equivalent voltage V of principal oscillation at high temperature C1 The order of _HT increases. The secondary vibration corresponds to the voltage V. C2 According to the equivalent voltage V of the secondary vibration at low temperature C2 _LT, the equivalent voltage V of the secondary vibration at room temperature C2 _RT, equivalent voltage V of secondary vibration at high temperature C2 The order of _HT increases.

[0136] For example, in the loop filter voltage V C Greater than the equivalent voltage V of the principal vibration at lower temperatures C1 _LT is large and is equivalent to the voltage V of the secondary vibration at low temperature. C2 _LT small voltage, low temperature first threshold V TH1 _LT(V C1 _LT<V TH1 _LT<V C2 In the case of _LT), comparator 341 generates a high-level signal, under the loop filter voltage V C The first threshold V at low temperatureTH1 When the signal is below _LT, comparator 341 generates a low-level signal.

[0137] For example, in the loop filter voltage V C Greater than the principal vibration equivalent voltage V at room temperature C1 _RT is large and is greater than the equivalent voltage V of the secondary vibration at room temperature C2 _RT small voltage, first threshold V at room temperature TH1 _RT(V C1 _RT<V TH1 _RT<V C2 In the case of _RT), comparator 341 generates a high-level signal, under the loop filter voltage V C The first threshold V at room temperature TH1 When the signal is below _RT, comparator 341 generates a low-level signal.

[0138] For example, in the loop filter voltage V C Greater than the equivalent voltage V of the principal vibration at higher temperatures C1 _HT is larger than the voltage V equivalent to the secondary vibration at high temperature. C2 _HT low voltage, high temperature first threshold V TH1 _HT(V C1 _HT<V TH1 _HT<V C2 In the case of _HT), comparator 341 generates a high-level signal, under the loop filter voltage V C The first threshold V at high temperature TH1 When the signal level is below _HT, comparator 341 generates a low-level signal.

[0139] The oscillation circuit 100C according to the fourth embodiment controls the oscillation signal S generated by the oscillator 20. XOSC frequency f XOSC The multiplication ratio is adjusted based on the input voltage of the voltage-controlled oscillator 35, i.e., the loop filter voltage V. C This controls the oscillator 20. Thus, a high-precision oscillator circuit 100C can be achieved.

[0140] Furthermore, the oscillation circuit 100C according to the fourth embodiment can use a first threshold V, which is used as determination data for determining whether to attenuate the oscillator 20, as the determination data. TH1 The value is adjusted to the optimal value in response to temperature changes. This enables the oscillation circuit 100C to reduce judgment errors caused by temperature variations.

[0141] <Fifth Implementation Method>

[0142] Reference Figure 12An example of the structure of the oscillation circuit 100D according to the fifth embodiment will be described.

[0143] The oscillation circuit 100D according to the fifth embodiment differs from the oscillation circuit 100C according to the fourth embodiment in that: the oscillation circuit 100D according to the fifth embodiment has a switching transistor SW1 between the attenuation control circuit 34C and the resistor R1, a switching transistor SW2 between the attenuation control circuit 34C and the oscillator 20, a switching transistor SW3 in the power-off timer circuit 38, and a switching transistor SW4 between the power-off timer circuit 38 and the oscillator 20. Furthermore, the other structures are the same as those of the oscillation circuit 100C according to the fourth embodiment, therefore, repeated descriptions are omitted.

[0144] The oscillation circuit 100D includes a resonator 10, an oscillator 20, a phase-locked loop circuit 30D, a storage unit 40B, and an interface unit 50. The phase-locked loop circuit 30D includes a first frequency divider 31, a phase comparator 32, a charge pump 33, an attenuation control circuit 34, a voltage-controlled oscillator 35, a second frequency divider 36, a lock-in detection circuit 37, and a power-off timer circuit 38D.

[0145] The oscillator circuit 100D has a switching transistor SW1 between the attenuation control circuit 34C and the resistor R1, a switching transistor SW2 between the attenuation control circuit 34C and the oscillator 20, a switching transistor SW3 in the power-off timer circuit 38, and a switching transistor SW4 between the power-off timer circuit 38 and the oscillator 20.

[0146] The oscillation circuit 100D uses external filters (e.g., capacitors C1, C3, etc.) appropriately based on the on / off states of switching transistors SW1, SW2, SW3, and SW4. For example, when the phase-locked loop circuit 30D is de-energized, the oscillation circuit 100D uses an external filter as a noise reduction filter for the oscillator 20. For example, when the phase-locked loop circuit 30D is not de-energized, the oscillation circuit 100D uses an external filter for the loop filter of the phase-locked loop circuit 30D or for the power-off timer circuit 38D of the phase-locked loop circuit 30D.

[0147] External filters offer a high capacity that cannot be integrated into integrated circuits. Therefore, for example, when an external filter is used for the loop filter of the phase-locked loop circuit 30D, the oscillation circuit 100D can adequately ensure that the oscillation signal S of the oscillator 20 is transmitted through the loop. XOSC The time is set to the power-off mode. Alternatively, for example, if an external filter is used in the power-off timer circuit 38D of the phase-locked loop circuit 30D, the oscillation circuit 100D can adequately ensure the waiting time until the phase-locked loop circuit 30B is powered off.

[0148] In addition, as a noise reduction node for the oscillator 20, for example, a voltage node for analog temperature compensation or an analog voltage node for annual variation correction of the oscillation frequency can be used.

[0149] The oscillation circuit 100D according to the fifth embodiment controls the oscillation signal S generated by the oscillator 20. XOSC frequency f XOSC The multiplication ratio is adjusted based on the input voltage of the voltage-controlled oscillator 35, i.e., the loop filter voltage V. C This controls the oscillator 20. Thus, a high-precision oscillator circuit 100D can be achieved.

[0150] Furthermore, the oscillation circuit 100D according to the fifth embodiment appropriately uses an external filter based on the on / off state of each switching transistor. Therefore, it is unnecessary to prepare separate filters for the oscillator 20 and for the phase-locked loop circuit 30D, thus enabling the realization of an oscillation circuit 100D with a reduced package size. Such an oscillation circuit 100D is particularly useful in applications such as small base stations.

[0151] The above-described embodiments are representative examples, but various modifications and substitutions can be made within the spirit and scope of the present invention, as will be apparent to those skilled in the art. Therefore, the present invention should not be construed as being limited to the above-described embodiments, and various modifications and alterations can be made without departing from the scope of the claims. For example, multiple structural blocks shown in the structural diagrams of the embodiments can be combined into one structural block, or a structural block can be divided. Furthermore, multiple steps shown in the flowcharts of the embodiments can be combined into one step, or a step can be divided.

[0152] Explanation of reference numerals in the attached figures

[0153] 10: Resonator; 20: Oscillator; 30: Phase-Locked Loop (PLL) circuit; 30A: PLL circuit; 30B: PLL circuit; 30C: PLL circuit; 30D: PLL circuit; 31: First frequency divider; 32: Phase comparator; 33: Charge pump; 33A: Charge pump; 34: Attenuation control circuit; 34C: Attenuation control circuit; 35: Voltage-controlled oscillator; 36: Second frequency divider; 37: Lock-in detection circuit; 38: Power-off timer circuit; 40: Storage Storage section; 40A: Storage section; 40B: Storage section; 50: Interface section; 100: Oscillator circuit; 100A: Oscillator circuit; 100B: Oscillator circuit; 100C: Oscillator circuit; 100D: Oscillator circuit; 200: Control circuit; 331a: Constant current source; 331b: Constant current source; 332a: Switching transistor; 332b: Switching transistor; 341: Comparator; 342: Comparator; 343: SR latch circuit; 344: Temperature sensor.

Claims

1. An oscillation circuit, characterized in that, have: An oscillator that causes a resonator to oscillate, thereby generating a first oscillation signal; and A phase-locked loop circuit adjusts the ratio of a first frequency of the first oscillation signal to a second frequency of the second oscillation signal output from a voltage-controlled oscillator, and controls the oscillator based on the input voltage of the voltage-controlled oscillator, i.e., the loop filter voltage. The phase-locked loop circuit further comprises: A voltage-controlled oscillator, whose input loop filter voltage is used; and A frequency divider circuit adjusts the ratio of the first frequency to the second frequency in such a way that the loop filter voltage becomes the equivalent voltage of the secondary vibration, wherein the equivalent voltage of the secondary vibration refers to the loop filter voltage when the resonator undergoes secondary vibration.

2. The oscillation circuit according to claim 1, characterized in that, The phase-locked loop circuit further includes an attenuation control circuit, which controls the oscillation of the oscillator based on the loop filter voltage. Wherein, when the loop filter voltage is greater than a first threshold, the attenuation control circuit causes the oscillator to attenuate; when the loop filter voltage is less than a second threshold, the attenuation control circuit causes the oscillator to oscillate. The first threshold is a voltage greater than the primary vibration equivalent voltage and less than the secondary vibration equivalent voltage, and the second threshold is a voltage less than the primary vibration equivalent voltage. The primary vibration equivalent voltage refers to the loop filter voltage when the resonator undergoes primary vibration.

3. The oscillation circuit according to claim 2, characterized in that, The attenuation control circuit repeatedly attenuates and oscillates the oscillator until the loop filter voltage converges to the voltage equivalent to the main oscillation.

4. The oscillation circuit according to claim 2, characterized in that, The attenuation control circuit includes a temperature sensor for measuring the temperature of the phase-locked loop circuit. The attenuation control circuit adjusts the first threshold based on the measurement results from the temperature sensor.

5. The oscillation circuit according to claim 1, characterized in that, The phase-locked loop circuit adjusts the ratio of the first frequency to the second frequency to 1:1 or the ratio of the frequency during the main vibration to the frequency during the secondary vibration.

6. The oscillation circuit according to claim 5, characterized in that, The ratio of the frequency of the primary vibration to the frequency of the secondary vibration is 10 to 11.

7. The oscillation circuit according to claim 1, characterized in that, The phase-locked loop circuit further includes a charge pump, which adjusts the rise time of the loop filter voltage rise or the fall time of the loop filter voltage fall.

8. The oscillation circuit according to claim 1, characterized in that, The phase-locked loop circuit further includes: A lock detection circuit detects whether the phase-locked loop circuit is in a locked state; and A power-off timer circuit, which, after detecting that the phase-locked loop circuit is in a locked state, de-energizes the phase-locked loop circuit.

9. The oscillation circuit according to claim 8, characterized in that, When the phase-locked loop circuit is de-energized, the oscillation circuit uses an external filter as a noise reduction filter for the oscillator. When the phase-locked loop circuit is not powered off, the oscillation circuit uses the external filter for the loop filter of the phase-locked loop circuit or the power-off timer circuit.

10. The oscillation circuit according to claim 2, characterized in that, The attenuation control circuit includes a temperature sensor for measuring the temperature of the phase-locked loop circuit. The attenuation control circuit controls the oscillator based on the measurement results of the temperature sensor.

11. The oscillation circuit according to claim 1, characterized in that, The phase-locked loop circuit further includes: A phase comparator that generates a phase comparison signal corresponding to the phase difference between the first oscillation signal and the second oscillation signal; and A charge pump, which is input to the phase comparison signal, adjusts the rise time of the loop filter voltage rise or the fall time of the loop filter voltage fall.

12. The oscillation circuit according to claim 7 or 11, characterized in that, If the charge pump current generated by the charge pump is greater than the optimal value, the charge pump adjusts the charge pump current to lengthen the rise time of the loop filter voltage or the fall time of the loop filter voltage. When the charge pump current is less than the optimal value, the charge pump adjusts the charge pump current to shorten the rise time of the loop filter voltage or the fall time of the loop filter voltage.

13. An oscillation circuit, characterized in that, have: An oscillator that causes a resonator to oscillate, thereby generating a first oscillation signal; and A phase-locked loop circuit adjusts the ratio of a first frequency of the first oscillation signal to a second frequency of the second oscillation signal output from the voltage-controlled oscillator, and controls the oscillator based on the input voltage of the voltage-controlled oscillator, i.e., the loop filter voltage. The phase-locked loop circuit further includes an attenuation control circuit, which controls the oscillation of the oscillator based on the loop filter voltage. When the loop filter voltage is greater than a first threshold, the attenuation control circuit causes the oscillator to attenuate; when the loop filter voltage is less than a second threshold, the attenuation control circuit causes the oscillator to oscillate. The first threshold is a voltage greater than the equivalent voltage of the primary oscillation and less than the equivalent voltage of the secondary oscillation, and the second threshold is a voltage less than the equivalent voltage of the primary oscillation. Wherein, the primary vibration equivalent voltage refers to the loop filter voltage when the resonator undergoes primary vibration, and the secondary vibration equivalent voltage refers to the loop filter voltage when the resonator undergoes secondary vibration.

14. The oscillation circuit according to claim 13, characterized in that, The attenuation control circuit repeatedly attenuates and oscillates the oscillator until the loop filter voltage converges to the voltage equivalent to the main oscillation.

15. The oscillation circuit according to claim 13, characterized in that, The attenuation control circuit includes a temperature sensor for measuring the temperature of the phase-locked loop circuit. The attenuation control circuit adjusts the first threshold based on the measurement results from the temperature sensor.

16. The oscillation circuit according to claim 13, characterized in that, The attenuation control circuit includes a temperature sensor for measuring the temperature of the phase-locked loop circuit. The attenuation control circuit controls the oscillator based on the measurement results of the temperature sensor.

17. An oscillation method, characterized in that, Includes the following steps: The oscillator causes the resonator to oscillate, thereby generating the first oscillation signal; The phase-locked loop circuit adjusts the ratio of the first frequency of the first oscillation signal to the second frequency of the second oscillation signal output from the voltage-controlled oscillator; and The phase-locked loop circuit controls the oscillator based on the input voltage of the voltage-controlled oscillator, i.e., the loop filter voltage. In the step of adjusting the ratio, the ratio of the first frequency to the second frequency is adjusted so that the loop filter voltage becomes the equivalent voltage of the secondary vibration, wherein the equivalent voltage of the secondary vibration refers to the loop filter voltage when the resonator undergoes secondary vibration.

18. The oscillation method according to claim 17, characterized in that, In the step of controlling the oscillator, when the loop filter voltage is greater than a first threshold, the phase-locked loop circuit causes the oscillator to attenuate; when the loop filter voltage is less than a second threshold, the phase-locked loop circuit causes the oscillator to oscillate. The first threshold is a voltage that is greater than the primary vibration equivalent voltage and less than the secondary vibration equivalent voltage, and the second threshold is a voltage that is less than the primary vibration equivalent voltage. The primary vibration equivalent voltage refers to the loop filter voltage when the resonator undergoes primary vibration.

19. The oscillation method according to claim 18, characterized in that, In the step of controlling the oscillator, the phase-locked loop circuit repeatedly causes the oscillator to decay and oscillate until the loop filter voltage converges to the voltage equivalent to the main oscillation.

20. The oscillation method according to claim 18, characterized in that, In the step of controlling the oscillator, the phase-locked loop circuit adjusts the first threshold based on the temperature measurement of the phase-locked loop circuit.

21. The oscillation method according to claim 17, characterized in that, In the step of adjusting the ratio, the phase-locked loop circuit adjusts the ratio of the first frequency to the second frequency to 1:1 or the ratio of the frequency during the main vibration to the frequency during the secondary vibration.

22. The oscillation method according to claim 21, characterized in that, The ratio of the frequency of the primary vibration to the frequency of the secondary vibration is 10 to 11.

23. The oscillation method according to claim 17, characterized in that, In the step of controlling the oscillator, the phase-locked loop circuit also controls the oscillator based on the temperature measurement results of the phase-locked loop circuit.

24. An oscillation method, characterized in that, Includes the following steps: The oscillator causes the resonator to oscillate, thereby generating the first oscillation signal; The phase-locked loop circuit adjusts the ratio of the first frequency of the first oscillation signal to the second frequency of the second oscillation signal output from the voltage-controlled oscillator; and The phase-locked loop circuit controls the oscillator based on the input voltage of the voltage-controlled oscillator, i.e., the loop filter voltage. In the step of controlling the oscillator, when the loop filter voltage is greater than a first threshold, the phase-locked loop circuit causes the oscillator to attenuate; when the loop filter voltage is less than a second threshold, the phase-locked loop circuit causes the oscillator to oscillate. The first threshold is a voltage greater than the primary vibration equivalent voltage and less than the secondary vibration equivalent voltage, and the second threshold is a voltage less than the primary vibration equivalent voltage. The primary vibration equivalent voltage refers to the loop filter voltage when the resonator is in primary vibration, and the secondary vibration equivalent voltage refers to the loop filter voltage when the resonator is in secondary vibration.

25. The oscillation method according to claim 24, characterized in that, In the step of controlling the oscillator, the phase-locked loop circuit repeatedly causes the oscillator to decay and oscillate until the loop filter voltage converges to the voltage equivalent to the main oscillation.

26. The oscillation method according to claim 24, characterized in that, In the step of controlling the oscillator, the phase-locked loop circuit adjusts the first threshold based on the temperature measurement of the phase-locked loop circuit.

27. A method for adjusting an oscillating circuit, characterized in that, The oscillation circuit includes an oscillator, a phase-locked loop circuit, and a control unit. The adjustment method of the oscillation circuit includes the following steps: The oscillator causes the resonator to oscillate, thereby generating a first oscillation signal; In the first adjustment step, the control unit adjusts the ratio of the first frequency of the first oscillation signal to the second frequency of the second oscillation signal output from the voltage-controlled oscillator in the phase-locked loop circuit so that the loop filter voltage input to the voltage-controlled oscillator of the phase-locked loop circuit becomes the secondary vibration equivalent voltage, wherein the secondary vibration equivalent voltage refers to the loop filter voltage when the resonator undergoes secondary vibration; In the second adjustment step, the control unit adjusts the first threshold based on the loop filter voltage adjusted in the first adjustment step. In the third adjustment step, the control unit adjusts the ratio of the first frequency of the first oscillation signal to the second frequency of the second oscillation signal output from the voltage-controlled oscillator in such a way that the loop filter voltage adjusted in the first adjustment step becomes the dominant oscillation voltage, wherein the dominant oscillation voltage refers to the loop filter voltage when the resonator undergoes dominant oscillation; and In the fourth adjustment step, the control unit adjusts the second threshold based on the loop filter voltage adjusted in the third adjustment step.

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