Enhancing temperature stability in reference clock applications with resonator arrays

Abstract

The invention relates to enhancing temperature stability in reference clock applications with resonator arrays. Embodiments herein relate to a reference clock including an array of resonators having different flip temperatures. The resonator may be, for example, a micro-electro-mechanical system (MEMS) resonator having different doping concentrations, or a quartz crystal resonator having different cut angles. In particular, for MEMS resonators, the flip temperature can be adjusted by providing overlying oxide layers of different thicknesses. In another aspect, the resonators are silicon-based piezoelectric resonators having different finger pitch to thickness ratios. A control circuit obtains a sensed temperature from the temperature sensor and selects one of the resonators having a flipped temperature in a temperature range corresponding to the sensed temperature. Each resonator may have a flipping temperature in a different temperature range. The resonators may have separate drivers, or have a common driver.

Description

Technical Field

[0001] The present application relates generally to clock generators and, more particularly, to clock generators using resonators. Background Art

[0002] A clock generator is an electronic oscillator that generates a clock signal on an integrated circuit or chip. The clock signal, also known as a reference clock, is provided to synchronize the operation of different circuits on the chip. In some cases, other clocks are derived from the reference clock and distributed on the chip. In general, the reference clock can be distributed to one or more chips. The clock generator may include, for example, a quartz crystal resonator or a microelectromechanical systems (MEMS) resonator, which vibrates at a specific resonant frequency when stimulated by a signal from a driver. However, maintaining a stable frequency of the clock signal under different conditions faces various challenges. Summary of the invention

[0003] One aspect of the present disclosure provides an apparatus. The apparatus includes: a group of resonators having different flip temperatures; at least one driver; a group of switches for coupling the at least one driver to the group of resonators; and a control circuit coupled to the group of switches, wherein the control circuit is used to obtain a temperature from a temperature sensor, classify the temperature into a selected temperature range among a plurality of temperature ranges, and control the group of switches to couple the at least one driver to a first selected resonator having a flip temperature in the selected temperature range among the group of resonators.

[0004] Another aspect of the present disclosure provides an apparatus. The apparatus includes: at least one driver for driving a first resonator having a first flip temperature and a second resonator having a second flip temperature, the second flip temperature being different from the first flip temperature; a set of switches coupled to the at least one driver; and a control circuit coupled to the set of switches, wherein the control circuit is used to: obtain a temperature from a temperature sensor; when the temperature is in a first temperature range corresponding to the first flip temperature, control the set of switches to couple the at least one driver to the first resonator; and when the temperature changes to a second temperature range corresponding to the second flip temperature, control the set of switches to couple the at least one driver to the second resonator.

[0005] Another aspect of the present disclosure provides an apparatus. The apparatus includes: a memory for storing instructions; and a processor for executing the instructions, so that: a temperature is obtained from a temperature sensor; a temperature is determined to be in a first temperature range; and based on the determination that the temperature is in the first temperature range, a set of switches is controlled to couple at least one driver to a first resonator in a set of resonators, wherein the first resonator has a flip temperature in the first temperature range.

[0006] Another aspect of the present disclosure provides a method. The method includes: obtaining a temperature from a temperature sensor; determining that the temperature is in a first temperature range; and based on determining that the temperature is in the first temperature range, controlling a set of switches to couple at least one driver to a first resonator in a set of resonators, wherein the first resonator has a flip temperature in the first temperature range.

[0007] Another aspect of the present disclosure provides a non-transitory machine-readable storage medium. The medium includes machine-readable instructions. When these instructions are executed, a processor or other circuit or computing device performs a method. The method includes: obtaining a temperature from a temperature sensor; determining that the temperature is in a first temperature range; and based on determining that the temperature is in the first temperature range, controlling a set of switches to couple at least one driver to a first resonator in a set of resonators, wherein the first resonator has a flip temperature in the first temperature range, wherein the set of resonators has different flip temperatures. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The embodiments of the present disclosure will be more fully understood through the detailed description given below and through the drawings of various embodiments of the present disclosure, however the detailed description and drawings should not be understood as limiting the present disclosure to specific embodiments but are only for illustration and understanding.

[0009] Figure 1 An example reference oscillator circuit 100 having one driver and three resonators is depicted in accordance with various embodiments.

[0010] Figure 2 An example reference oscillator having a separate driver for each of three resonators is depicted in accordance with various embodiments.

[0011] Figure 3A Depicted are example graphs of frequency drift versus temperature for an uncompensated MEMS resonator in accordance with various embodiments.

[0012] Figure 3B An example resonator device 305 is depicted that includes a MEMS resonator 311 formed on a substrate 310 and an oxide layer 312 formed on the MEMS resonator 311 , according to various embodiments.

[0013] Figure 3C An example resonator device 345 is depicted that includes interdigitated electrodes 350 and 360 in a MEMS resonator formed on a substrate 340 .

[0014] Figure 4 Depicted are various embodiments of Figure 1 and Figure 2Example plot of frequency drift versus temperature for a consistent resonator array.

[0015] Figure 5 Another example graph of frequency drift versus temperature for a resonator array according to various embodiments is depicted.

[0016] Figure 6 An example reference oscillator having one driver and two resonators is depicted in accordance with various embodiments.

[0017] Figure 7 Depicted are various embodiments of Figure 6 Example plot of frequency drift versus temperature for a consistent resonator array.

[0018] Figure 8 Depicted are various embodiments Figure 6 Example plots of the output voltage (Xout) versus time of a reference oscillator with a second resonator added at different times.

[0019] Fig. 9 A flow chart is depicted of an example process for selecting a resonator in an array of resonators in accordance with various embodiments.

[0020] Fig.10 Depicted are various embodiments of Fig. 9 Example switching signal during a consistent transition.

[0021] Fig.11 Illustrations illustrate examples of components that may be present in a computing system 1150 for implementing the techniques (eg, operations, processes, methods, and approaches) described herein. DETAILED DESCRIPTION

[0022] As mentioned at the outset, there are various challenges in maintaining a stable frequency of a clock signal in an oscillator circuit.

[0023] Reference oscillators are essentially feedback amplifiers that utilize a frequency selective component (e.g., a quartz or MEMS resonator) in the feedback loop. This component only allows signals to pass at its resonant frequency, which creates a forward loop and generates a sine wave oscillation at the same frequency as the resonator. The thermal stability of the oscillator depends largely on the stability of the frequency selective component.

[0024] These oscillators may be arranged in, for example, an integrated circuit, a system in package (SiP), a system on a chip (SoC), or a stacked tile / chiplet design that includes multiple integrated circuits / chips in the same package.

[0025] To meet consumer demand for high performance and low power, computing systems require high-frequency reference oscillators with low jitter and minimal power consumption. Quartz resonators offer better thermal stability than MEMS resonators, but their resonant frequencies are limited to a few hundred MHz, and they cannot be fabricated on complementary metal-oxide semiconductor (CMOS) chips, resulting in increased routing parasitics. These parasitics are particularly critical for high-frequency reference clock applications. On the other hand, MEMS resonators are suitable for high-frequency reference clock applications. They can achieve resonant frequencies up to several GHz and can potentially be fabricated on the same chip as the oscillator driver, resulting in smaller parasitics. However, for the commercial temperature range of -40°C to 80°C, their thermal stability falls in the range of several thousand ppm (parts per million), while the thermal stability of quartz crystals under the same conditions is less than 100 ppm.

[0026] One possible solution involves active temperature compensation techniques, such as baking or temperature sensing, combined with frequency correction through fractional phase-locked loops (PLLs). However, these techniques can increase the overall power budget, reduce performance, and increase manufacturing complexity. The need for high vacuum packaging may also increase the cost of the oscillator. In addition, the fractional PLL approach may increase the overall jitter of the reference clock due to the additional PLL. In addition, although the PLL can generate any frequency, this is at the expense of power consumption and jitter degradation.

[0027] Another possible solution is to use passive temperature compensation techniques, such as adding dopants to the resonator material layer, or adding additional positive temperature coefficient of elasticity (TCE) layers, such as silicon dioxide, to the resonator structure. However, these techniques may also have limitations in achieving the desired level of temperature stability. For example, the final temperature stability may still be greater than that of a quartz crystal, which may be a concern for some applications.

[0028] The solution provided herein addresses the above and other challenges. In one aspect, the solution provides an array of resonators with similar frequencies but different turnover temperatures. The turnover temperature is a specific temperature on a second-order curve of a temperature coefficient of frequency (TCF) versus temperature graph at which the polarity of the frequency change changes from positive to negative (the maximum point in the TCF versus temperature curve). Based on the number of resonators in the array, the temperature range is divided into smaller parts. For example, if there are three resonators, the entire temperature range is divided into three smaller parts, each corresponding to a resonator. Each resonator is optimized to provide a turnover temperature in the middle of each smaller part. The solution also includes a temperature sensor and a circuit for switching between resonators to select which resonator is connected to the oscillator driver at different temperature ranges. As a result, very high frequency stability, such as less than 100 parts per million (ppm), can be achieved. These solutions take advantage of the fact that the frequency drift of MEMS-based resonators (e.g., piezoelectric resonators, piezoelectric resonators on silicon, and silicon resonators) versus temperature follows a second-order quadratic curve, with the frequency drift being minimal over a temperature range close to the resonator's flip temperature. For example, the resonator may be a MEMS resonator, which typically measures about 200 μm x 200 μm. For example, an array of three such resonators would measure less than 1 mm x 1 mm, which is smaller than a typical single quartz crystal.

[0029] For MEMS resonators in particular, the flip temperature can be adjusted by providing a silicon oxide capping layer of varying thickness or by adding dopants to the silicon resonator. For quartz crystals, the flip temperature can be adjusted by selecting an appropriate angle for the crystal. The control circuit obtains a sensed temperature from a temperature sensor and selects one of the resonators having a flip temperature corresponding to the sensed temperature. Each resonator may correspond to a different temperature range. The resonators may have separate drivers, or may have a common driver. Transitions between resonators may involve injecting the signal of the current driver into the newly selected resonator to speed up the startup time and minimize phase differences during switching.

[0030] The solution provided herein overcomes the limitations of MEMS resonators in the context of reference clock applications, thereby facilitating the implementation of reference clocks in the GHz range. High frequency reference clocks advantageously exhibit reduced jitter and faster startup times compared to low frequency reference clocks.

[0031] These and other features will become further apparent from the discussion below.

[0032] Figure 1 An example reference oscillator circuit 100 having one driver 150 (single driver) and three resonators 110, 120, and 130 is depicted in accordance with various embodiments. The block diagram is a block diagram of a reference oscillator having an array of MEMS resonators connected as frequency selective components. The term oscillator is generally used to refer to the combination of a driver and a resonator. The resonators are arranged in parallel in an array 105. Generally, the array may include at least two resonators. In one approach, the resonators are of the same type. The driver may drive one or more resonators simultaneously. In one approach, a set of switches 103 is provided, including switches SW1, SW2, and SW3, for routing drive or excitation signals from the driver to the resonators 110, 120, and 130, respectively. The set of switches may be controlled by a control circuit 102, which in turn is responsive to temperature data / readings from a temperature sensor 101. The control circuit may include a memory 102a for storing instructions and a processor 102b for executing the instructions to provide the functionality described herein.

[0033] Examples of temperature sensors include silicon bandgap temperature sensors, thermistors, resistance temperature detectors, and thermocouples. A silicon bandgap temperature sensor includes a forward biased pn junction in which the change in base to emitter voltage corresponds to the device temperature. A thermistor is a passive component that changes resistance with temperature. A resistance temperature detector is made of pure materials such as platinum, nickel, or copper and has a highly predictable resistance-temperature relationship. A thermocouple is made of two different electrical conductors that form an electrical junction at different temperatures. Due to the thermoelectric Seebeck effect, a thermocouple generates a voltage that depends on temperature. MEMS-based temperature sensors can also be used. In general, any type of temperature sensor can be used.

[0034] In one embodiment, the switches include transistors that can be turned on (conducting) or off (non-conducting) by controlling their control gate voltages. In another embodiment, the switches include relay switches. When turned on, each switch couples the driver to path 111, 121, or 131 to excite resonators 110, 120, or 130, respectively, and forms a closed feedback loop with the driver. The switches are coupled to the driver and coupled to each other at path 151. Path 151 is coupled to resistor R and path 153, which carries the output signal Xout (reference clock signal) of the driver. The voltage on path 151 is applied to the control gate of the first transistor T1 connected in series with the second transistor T2. The transistors connected in series are coupled to a power supply node 152. Path 151 is also coupled to ground via switch SW4 and a first variable capacitor C1. Path 153 is coupled to ground via a second variable capacitor C2 and is coupled to the input of an amplifier controller 155. The output of the amplifier controller is coupled to a power supply node 156 via a path 157 and a switch SW5, which is controlled by an enable (EN) signal. EN is used to enable the driver 150. Path 157 is coupled to the control gate of transistor T2. In this implementation, T1 is an n-type metal-oxide-semiconductor field-effect transistor (MOSFET) and T2 is a p-type MOSFET.

[0035] The resonator is coupled to the various paths and switches on a first side and to a common path 160 on an opposing second side, which in turn is coupled to a point 161 between T1 and T2. For example, the resonator 110 may have a first side 110a and a second side 110b, respectively. The resonator 120 may have a first side 120a and a second side 120b, respectively. The resonator 130 may have a first side 130a and a second side 130b, respectively. For example, the opposing sides may be electrodes.

[0036] Circuit 100 thus replaces a single resonator with an array of resonators characterized by different flip temperatures. In one possible implementation, the resonator is a MEMS resonator. In another possible implementation, the resonator is a quartz crystal. The entire temperature range of circuit operation can be divided into smaller segments, such as Figure 4 , Figure 5 and Figure 7As shown in , and based on the temperature measured by a temperature sensor (which can be an undoped resonator or another type of temperature sensor), one of the resonators with a flip temperature in the range will be linked to the oscillator driver. For example, the frequency of a mechanical resonator can be affected by temperature. By comparing the frequency change of one resonator to another resonator, the corresponding temperature change can be measured.

[0037] Additionally, variable load capacitors can be used to adjust the center frequency of an array of resonators so that they are similar at room temperature. For example, the center frequency of a mechanical resonator is its natural resonant frequency and is independent of the flip temperature. The goal is to have the same natural resonant frequency for all resonators in the array. However, during the fabrication process, slight variations in dimensions can cause the natural resonant frequencies (center frequencies) of the resonators in the array to differ slightly. In order to achieve the desired frequency consistency, calibration is performed. This involves adjusting the resonator by adding a load so that its resonant frequency reaches the exact value desired. A variable load capacitor is employed for this purpose because it allows for fine tuning and precise adjustment of the resonant frequency of each resonator in the array.

[0038] The driver 150 in this example is a Pierce oscillator, but other driver architectures may be used. In addition, the number of resonators in the array may be optimized based on the desired level of stability. The greater the number of resonators, the greater the stability in terms of a stable oscillation frequency.

[0039] In an oscillator circuit, a resonator and a driver work together to generate and maintain oscillations at a desired frequency. The resonator determines the frequency of the oscillation, while the driver provides the energy necessary to maintain the oscillation. A resonator is a component that exhibits resonance at a specific frequency. When driven at this frequency, it can store and exchange energy between capacitive elements to produce oscillations. The driver is an active component, such as an operational amplifier, that provides energy to the resonator to compensate for energy losses in the circuit. It can amplify the signal generated by the resonator and provide the power necessary to maintain the oscillation. The driver also shapes the waveform and ensures the stability and reliability of the oscillation.

[0040] The oscillator circuit includes a feedback loop that connects the output of the driver back to the resonator. This feedback loop enables the circuit to maintain oscillation by constantly reinforcing the natural frequency of the resonator. The driver amplifies the signal from the resonator and feeds it back into the resonator, effectively providing positive feedback. This feedback helps to compensate for energy losses and maintain the desired oscillation frequency.

[0041] When power is initially applied to the oscillator circuit, it will begin to oscillate on its own, but the start-up time will be relatively long, e.g., milliseconds. Instead, an initial signal can be provided to initiate oscillations, shortening the start-up time, e.g., to microseconds. This can be accomplished by injecting a small signal or noise into the resonator, allowing the driver to amplify it and establish oscillations. Once oscillations have been initiated, the feedback loop takes over and maintains the oscillations.

[0042] Figure 2 An example reference oscillator 200 having a separate driver for each of the three resonators is depicted in accordance with various embodiments. In this example, a first driver, driver 1 210, may be coupled to the first resonator 110 via respective switches SW1 and paths 111 and 211, a second driver, driver 2 220, may be coupled to the second resonator 120 via respective switches SW2 and paths 121 and 221, and a third driver, driver 3 230, may be coupled to the third resonator 130 via respective switches SW3 and paths 131 and 231. Each driver may have a Figure 1 The driver 150 of FIG. 1 is similarly configured, but the drivers are independently operated when driving each resonator. The choice of whether to have a common driver or separate drivers can be based on, for example, the technology selected for switching between resonators, which will be discussed further below.

[0043] Figure 3A An example graph of frequency drift versus temperature for an uncompensated MEMS resonator according to various embodiments is depicted. Frequency drift or sensitivity is represented by a temperature coefficient of frequency (TCF) curve. TCF is the rate at which frequency changes with temperature relative to a reference frequency. The MEMS resonator is uncompensated because no additional techniques are used to move the flip temperature to a higher level. Frequency drift can be measured in parts per million. For example, if the clock frequency is 10 MHz, a drift of -1000 ppm corresponds to a drift of -10 KHz. The MEMS resonator has quadratic temperature stability. In this example, the flip temperature is approximately -100°C. Within a small temperature range around this flip temperature, the frequency drift is negligible. However, this temperature is below the range of use for most computing devices. The flip temperature is the temperature at the peak of the graph, where the frequency drift is 0. Frequency drift increases on either side of the flip temperature.

[0044] Various techniques can be used to shift the flipping temperature of a MEMS resonator toward a higher temperature, into a desired commercial temperature range, such as -40 to 80°C. For example, for silicon resonators and silicon-based piezoelectric resonators, the flipping temperature can be shifted toward a higher temperature by including doping into the silicon layer. Example dopants include boron, antimony, arsenic, and phosphorus. Higher doping levels (doping concentrations) can shift the flipping temperature higher. For example, for phosphorus, a doping concentration of 10^19 / cm3 can increase the flipping temperature to 90°C, while no doping would result in a flipping temperature below -100°C. For example, doping concentrations between zero and 10^19 / cm3 can result in a flipping temperature from below -100°C to above 90°C. Doping is believed to affect the elastic properties of the resonator. For example, Figure 3B The silicon substrate 310 may be doped. In addition to the doping level, the flip temperature position also depends on the resonant mode shape. Therefore, at the same doping level, two different mode shapes may have two different flip temperatures. At the same or different doping concentrations, the resonators in the array may have different resonant mode shapes. In an example implementation, each resonator in the resonator group includes a microelectromechanical system (MEMS) resonator, and the doping concentration is different for each MEMS resonator.

[0045] Another technique to shift the switching temperature is to add a layer with a positive temperature coefficient of elasticity, such as silicon dioxide (SiO2), to the resonator. This technique also shifts the switching temperature to higher temperatures and is applicable to all types of MEMS resonators. For example, a Figure 3B The oxide layer 312 of the present invention. A thicker oxide layer can result in a higher shift in the flip temperature. Specifically, a lower value of the flexural stiffness ratio corresponds to a higher flip temperature, wherein the flexural ratio refers to the flexural vibration mode of the resonator and can be defined as B(Si) / B(SiO2). B(Si) is the flexural stiffness of the silicon substrate 310, and B(SiO2) is the flexural stiffness of the SiO2 layer 312. The thicker the SiO2 layer, the higher the B(SiO2), the smaller the ratio, and therefore the higher the flip temperature. The technology provided herein is applicable to all mode shapes, not just the flexural mode (bending mode) described herein. Other mode shapes, such as epitaxial mode, Lamb mode, and Lame mode, are feasible with the addition of an oxide layer. In an exemplary implementation, each resonator in the resonator group includes an oxide layer, and the thickness of each oxide layer is different.

[0046] Various types of MEMS resonators that may be used include clamped-clamped resonators, cantilever resonators, fixed-fixed beam resonators, square plate resonators, disk resonators, ring resonators, and comb-drive resonators.

[0047] Another technique to shift the switching temperature is to adjust the finger pitch-to-thickness (FP / t) ratio. For example, for silicon-based piezoelectric resonators, the location of the switching temperature depends on the FP / t ratio. See also Figure 3C Thus, the doping amount, the thickness of the oxide layer, or the FP / t ratio may be adjusted to control the location of the flip temperature. In an example implementation, each resonator in the resonator group includes a silicon-based piezoelectric resonator, and the finger pitch to thickness (FP / t) ratio is different for each silicon-based piezoelectric resonator.

[0048] By utilizing these techniques, it is possible to tailor the flip temperature of a MEMS resonator to match the desired commercial temperature range.

[0049] Figure 3B An example resonator device 305 is depicted that includes a MEMS resonator 311 formed on a substrate 310 and an oxide layer 312 formed on the MEMS resonator 311, according to various embodiments. As previously described, the thickness (Th) of the oxide layer can be adjusted to adjust the flip temperature of the resonator device.

[0050] Figure 3C An example resonator device 345 is depicted that includes interdigitated electrodes 350 and 360 in a MEMS resonator formed on a substrate 340. The electrodes include fingers, such as example adjacent fingers 351 and 361, where the finger pitch (FP) is the distance between the centers of adjacent fingers. The electrodes can be formed of a metal film whose thickness refers to the dimension out of the page. The FP / t ratio can be defined as discussed, where the ratio can be adjusted to adjust the flip temperature of the resonator device.

[0051] Figure 4 Depicted are various embodiments of Figure 1 and Figure 2 Example plots of frequency drift versus temperature for a consistent resonator array. This is a temperature stability curve for an oscillator having a resonator array. Plots 400 and 400a show the frequency drift of a first resonator (e.g. Figure 2 110), and graphs 410, 410a, and 410b represent the frequency drift of a second resonator (e.g. Figure 2 ), and plots 420 and 420a represent the frequency drift of a third resonator (e.g. Figure 2 The frequency drift of the resonator 130).

[0052] The first resonator is optimized for a low temperature range, e.g., -40 to 0°C (temperature range TR1), where plot 400 shows a minimum frequency drift, e.g., in a range 450 of 0 to -Δppm. Plot 400a shows larger frequency drifts above this temperature range. However, these larger drifts would not be achieved if the first resonator were only used within its respective temperature range. The flip temperature of the first resonator is -20°C, located in the center of TR1.

[0053] The second resonator is optimized for an intermediate temperature range, e.g., 0 to 40°C (temperature range TR2), with plot 410 representing a minimum frequency drift within range 450. Plots 410a and 410b represent larger frequency drifts below and above this temperature range, respectively. However, these larger drifts would not be achieved if the second resonator were used only within its respective temperature range. The flip temperature of the second resonator is 20°C, located in the center of TR2.

[0054] The third resonator is optimized for a high temperature range, such as 40 to 80°C (temperature range TR3), where plot 420 represents the minimum frequency drift within range 450. Plot 420a represents larger frequency drifts below this temperature range. However, if the third resonator is used only within its respective temperature range, these larger drifts will not be achieved. The flip temperature of the third resonator is 60°C, which is located in the center of TR3.

[0055] In this example, each temperature range is of equal width (e.g., 40°C), but it is also possible to have ranges of different widths. For example, the temperature ranges could be smaller near the temperature of greatest interest to provide smaller frequency drift. For example, see Figure 5 .

[0056] Furthermore, the flip temperature of each resonator is set at the center of its specified temperature range. The frequency drift of the resonator array is represented by solid lines 400, 410 and 420.

[0057] As shown in the graph, the temperature stability of an oscillator using an array of MEMS resonators can be less than 100 ppm. If desired, a larger array of resonators can be used to further enhance the thermal stability of the oscillator.

[0058] In addition, temperature hysteresis can be used to avoid undesirably frequent switching between resonators when the temperature approaches the boundary between adjacent temperature ranges (the switching temperature). By applying hysteresis, the temperature at which a given resonator switches to the oscillator driver will be offset from the switching temperature by a certain amount, so that the oscillator can remain stable near the switching temperature. This can help reduce the impact of noise and other environmental factors that may cause small fluctuations in temperature that might otherwise trigger frequent switching between resonators.

[0059] For example, arrows 430 and 431 represent hysteresis ranges or bands around switching temperatures 0°C and 40°C, respectively. For example, assume that the range is + / -2°C. Thus, when the temperature exceeds 2°C, switching from TR1 to TR2 will occur, and when the temperature drops below -2°C, switching from TR2 to TR1 will occur. Similarly, when the temperature exceeds 42°C, switching from TR2 to TR3 will occur, and when the temperature drops below 38°C, switching from TR3 to TR2 will occur. Each switching temperature has a hysteresis range associated with it, which is the temperature at the boundary between adjacent temperature ranges. The hysteresis ranges can be equal, or they can be different.

[0060] In this example, the temperature ranges are of equal width, but they can also have different widths. Figure 5 In one approach, the flip temperature may be centered within its corresponding temperature range.

[0061] When switching occurs within a temperature range, additional or alternative restrictions may be imposed by setting a timer. For example, a specified / predetermined wait time may be imposed before switching to another resonator. A timer within the control circuit 102 may provide this wait time feature. The wait time feature should be used when sudden large temperature changes are not expected, as it may reduce stability in such situations. The control circuit may also include logic for implementing a hysteresis feature.

[0062] The technology provided in this article is applicable to different types of resonators. In addition to MEMS resonators, the same concept of enhancing temperature stability using an array of resonators with different flip temperatures can also be applied to quartz crystals. The flip temperature of a quartz crystal is determined by the quartz cutting angle, and the desired flip temperature can be achieved by adjusting the cutting angle. Therefore, in a manner similar to MEMS resonators, an array of quartz crystals with different cutting angles and corresponding flip temperatures can be utilized. By selecting an appropriate quartz crystal from the array based on the measured temperature, the frequency stability of the oscillator can be further improved. In an example implementation, each resonator in the resonator group includes a quartz crystal resonator, and the cutting angle of each quartz crystal resonator is different.

[0063] Figure 5Another example graph depicting the relationship between frequency drift and temperature for a resonator array according to various embodiments. In this example, there are five resonators with associated temperature ranges. In addition, the widths of the temperature ranges are not all equal. This approach provides different temperature regions with different levels of frequency drift. This approach may be useful when there is a temperature region of interest where a particularly low drift is desired. In general, the smaller the temperature range, the smaller the resulting frequency drift. For example, this may be the temperature region in which the device is most commonly operated. Plots 500, 510, 520, 530, and 540 are for the first to fifth resonators, respectively, and represent the frequency drift within the first to fifth temperature ranges, respectively.

[0064] Here, the adjacent temperature ranges are TR1-TR5. For TR3, the temperature range is the smallest, for TR2 and TR4 the second largest, and for TR1 and TR5 the largest. TR3 is the central region, TR2 and TR4 are adjacent to TR3 on opposite sides of TR3, and TR1 and TR5 are adjacent to TR2 and TR5, respectively. For example, TR1 is from -40°C to -5°C, TR2 is from -5°C to 17°C, TR3 is from 17°C to 23°C, TR4 is from 23°C to 45°C, and TR5 is from 45°C to 80°C. For TR3, the amplitude of the frequency drift is Δ1, for TR2 and TR4 it is Δ2, and for TR1 and TR5 it is Δ3, where Δ1<Δ2<Δ3. The scale of the y-axis is modified to show the frequency drift in more detail. In this example, the widths of the multiple temperature ranges are unequal and include the narrowest temperature range (TR3) and adjacent wider temperature ranges (TR2 and TR4).

[0065] Figure 6 An example reference oscillator 600 having one driver 610 and two resonators 620 and 630 according to various embodiments is depicted. In one approach, the driver can be a Pierce oscillator. The driver is coupled to ground on opposite sides via load capacitors Cload1 and Cload2 and paths 611 and 612, respectively. For example, one of the resonators can be selected based on temperature. When the first switch SWV1 is closed (conducting) and the second switch SWV2 is opened (non-conducting), the first resonator 620 is selected. The driver and resonator 620 together form an oscillator, wherein the driver provides an input signal Xin (excitation signal) to one side of the resonator on paths 611, 614, and 618, and the resonator provides an output signal Xout (feedback signal) on the opposite side at the output node 613 and path 612. Xout can be provided to other circuits at the output node 613 as a reference clock signal. SWV1 can be a relay switch or an electronic switch, such as a transistor. A voltage source 616 coupled to SWV1 provides a voltage Vsrc1 to control SWV1 , such as to open and close SWV1 .

[0066] Similarly, to select the second resonator 630, SWV1 is opened and SWV2 is closed. A voltage source 617 coupled to SWV2 provides a voltage Vsrc2 to control SWV2, such as to open and close SWV2. SWV2 is coupled to the driver 610 via path 615 and to the resonator 630 via path 619.

[0067] Figure 7 Depicted are various embodiments of Figure 6 Example plot of frequency drift versus temperature for a consistent array of resonators. In this case, the array has two resonators. The first resonator is selected when the temperature is in a first temperature range TR1 from 0 to 40°C, and the second resonator is selected when the temperature is in a second temperature range TR2 from 40 to 80°C. The frequency drift of the first resonator (plot 700) is within Δ when the first resonator is selected, and the frequency drift of the second resonator (plot 710) is within Δ when the first resonator is selected. For temperatures above TR1, the frequency of the first resonator decreases (plot 700a), and for temperatures below TR2, the frequency of the second resonator decreases (plot 710a). The temperature region of 0 to 80 is considered the operating range of the device, so temperatures below 0°C or above 80°C are not considered in this example.

[0068] Figure 8 Depicted are various embodiments Figure 6 Example plot of the output voltage (Xout) of a reference oscillator versus time with a second resonator added at different times. This data is based on using Figure 6 The test was performed on an example reference oscillator 600, where the resonator is from Kyocera TM 153.6MHz crystal.

[0069] The output voltage is the oscillator output with only one resonator connected and a second resonator added at seven different switching times (indicated by arrows 830-836). The output voltage includes three peaks. The first peak is represented by graph 800, the second peak is represented by graph 810 in the case of one resonator and graph 811 in the case of two resonators, and the third peak is represented by graph 820 in the case of one resonator and graph 821 in the case of two resonators. The addition of the second resonator tends to slightly reduce the peak amplitude. However, the second resonator is advantageously kept in phase with the first resonator. While the first resonator is operating, the second resonator can be added by closing the switch of the second resonator.

[0070] The plots show that by connecting both resonators to the same oscillator driver, a smooth transition between resonators can be achieved when the temperature is within a small temperature range around the switching point (e.g., within the hysteresis range). In this scheme, only one driver is used. The first resonator is turned off after the second resonator reaches full swing. To test the feasibility of this scheme, Figure 6 consistent, for the Kyocera connected to the same oscillator driver TM Two different 153.6MHz crystals were simulated using a simplified electrical model. Initially, only one crystal was connected to the driver, and within a 20ns time frame, the switch was closed to connect the second crystal to the driver. As shown, the phase change during switching is negligible, independent of the phase when the second crystal is connected.

[0071] Fig. 9 A flow chart of an example process of selecting a resonator in a resonator array according to various embodiments is depicted. Block 900 includes sensing a temperature, such as using a temperature sensor 101 for sensing. Block 901 includes classifying the temperature into a selected temperature range corresponding to the temperature. Block 902 includes selecting a resonator corresponding to the temperature range. The selected resonator may be considered a first selected resonator and may be any resonator discussed herein. Block 903 includes driving the selected resonator, such as by closing a switch coupling a driver to the selected resonator. The selected driver may be considered a first selected driver resonator and may be any driver discussed herein. Block 904 includes sensing the temperature again. If the decision block 905 determines that a new temperature (temp.) range (Y or Yes) should be used, block 906 transitions to another resonator. If the answer to the decision block is no or N, temperature sensing continues at block 904. When the temperature crosses a transition temperature, and optionally, crosses a hysteresis band such as a transition temperature, a new temperature range should be used. In some cases, the transition to another resonator may involve a transition to another driver. In this case, the other driver can be considered as the second selected driver. The other resonator can be considered as the second selected resonator.

[0072] Various techniques can be used to provide smooth transitions between different resonators in an array, avoiding phase changes and glitches during the switching process.

[0073] First, one possible way to prevent phase errors during switching between resonators is to use injection locking. In this scheme, each resonator has its own dedicated driver, such as Figure 2As the temperature approaches the switching point, the signal from the active driver (first driver) is injected into the resonator dedicated to the next temperature range (second resonator). As the signal of the second oscillator increases, the injection intensity is gradually reduced. This technique can speed up the startup time of the next oscillator and minimize the phase difference during the switching. For example, see Fig.10 .

[0074] A second possible approach to initially switching between resonators involves connecting both resonators to the same driver simultaneously when the temperature is within a small temperature range around the switching point (e.g., in the hysteresis range), such as contacting Figure 8 When the temperature crosses the transition temperature, the transition may occur. For example, as previously described, one of the resonators may be disconnected after a specified / predetermined waiting time after the start of the transition.

[0075] A third possible approach to switching between resonators involves frequency monitoring. In this approach, each resonator requires its own dedicated driver. When the frequencies of the two oscillators reach the same value, it is time to switch to the second oscillator. The phase difference between the two oscillators can be measured, and the phase of the second oscillator can be aligned with the first. This approach eliminates phase errors during switching and does not require a temperature sensor because the switching time is determined by monitoring the oscillator frequency.

[0076] Fig.10 Depicted are various embodiments of Fig. 9 Example switching signals during a consistent transition. Initially, SWV1 is on, so the associated first resonator is driven and active, and SWV2 is off, so the associated second resonator is not driven and inactive. At t0, at the start of the transition from the first resonator to the second resonator, SWV2 begins to transition to the on position. At t1, both SWV2 and SWV1 are on, so both the first resonator and the second resonator are driven. At t2, SWV1 begins to turn off, and reaches the off position at t3. At this point, only the second resonator is driven, and the first resonator is no longer driven.

[0077] In one approach, a common driver is provided for each resonator. When a change occurs from a first resonator to a second resonator based on temperature crossing a transition temperature, the control circuit may control the set of switches to temporarily drive both resonators simultaneously. The driver may inject its output signal into the second resonator to accelerate the start-up time of the second resonator and lock the phase of the second resonator to the phase of the first resonator. Subsequently, the switches are controlled so that the driver drives only the second resonator and stops driving the first resonator.

[0078] In one approach, a different driver is provided for each resonator. For example, a first driver is provided to drive the first resonator, and a second driver is provided to drive the second resonator. When the temperature changes from a first temperature range corresponding to a first flip temperature of the first resonator to a second temperature range corresponding to a second flip temperature of the second resonator, the control circuit controls the set of switches to couple both the first driver and the second driver to the second resonator, and then couple the second driver to the second resonator, but not couple the first driver to the second resonator.

[0079] Fig.11 An example of components that may be present in a computing system 1150 for implementing the techniques (eg, operations, processes, methods, and approaches) described herein are illustrated. The resonator arrays and associated drivers described herein may be part of a reference clock 1190.

[0080] Communications external to the computing system may go through interface circuit 1170 to external device 1172 .

[0081] A power supply 1100 (eg, a voltage converter) may provide power to one or more components of a computing system 1150 .

[0082] The memory circuit 1154 may store instructions, and the processor circuit 1152 may execute the instructions to perform the functions described herein.

[0083] The computing system 1150 may include any combination of the hardware or logic components mentioned herein. These components may be implemented as ICs, portions thereof, discrete electronic devices, or other modules, instruction sets, programmable logic or algorithms, hardware, hardware accelerators, software, firmware, or combinations thereof adapted in the computing system 1150, or as components otherwise contained within a housing of a larger system. For one embodiment, at least one processor 1152 may be packaged together with computing logic 1182 and configured to implement aspects of the various example embodiments described herein to form a system-in-package (SiP) or system-on-chip (SoC).

[0084] System 1150 includes a processor circuit in the form of one or more processors 1152. Processor circuit 1152 includes circuits such as (but not limited to): one or more processor cores and one or more of the following: cache memory, low drop-out (LDO) voltage regulator, interrupt controller, serial interface such as SPI, I2C or general programmable serial interface circuit, real time clock (RTC), timer-counter including interval and watchdog timer, general I / O, memory card controller such as secure digital / multi-media card (SD / MMC), interface, mobile industry processor interface (MIPI) interface and joint test access group (JTAG) test access port. In some implementations, processor circuit 1152 may include one or more hardware accelerators (e.g., the same or similar to acceleration circuit 1164), which may be microprocessors, programmable processing devices (e.g., FPGA, ASIC, etc.), etc. One or more accelerators may include, for example, computer vision and / or deep learning accelerators. In some implementations, the processor circuit 1152 may include on-chip memory circuitry, which may include any suitable volatile and / or non-volatile memory, such as DRAM, SRAM, EPROM, EEPROM, flash memory, solid-state memory, and / or any other type of memory device technology, such as those discussed herein.

[0085] The processor circuit 1152 may include, for example, one or more processor cores (CPUs), application processors, GPUs, RISC processors, Acorn RISC Machine (ARM) processors, CISC processors, one or more DSPs, one or more FPGAs, one or more PLDs, one or more ASICs, one or more baseband processors, one or more radio-frequency integrated circuits (RFICs), one or more microprocessors or controllers, multi-core processors, multi-threaded processors, ultra-low voltage processors, embedded processors, or any other known processing elements, or any suitable combination of these. The processor (or core) 1152 may be coupled to or may include a memory / storage device, and may be configured to execute instructions stored in the memory / storage device to enable various applications or operating systems to run on the platform 1150. The processor (or core) 1152 is configured to operate application software to provide specific services to users of the platform 1150. In some embodiments, the (one or more) processors 1152 may be (or may be configured to) be (one or more) dedicated processors / controllers configured to operate according to various embodiments herein.

[0086] As an example, the processor(s) 1152 may include Core based architecture TM Processors such as i3, i5, i7, i9 based processors; Microcontroller-based processors such as Quark TM 、Atom TM Or other MCU-based processors; (one or more) Processor(s), processor, or available from Santa Clara, California However, any number of other processors may be used, such as one or more of the following: Advanced Micro Devices (AMD) Architecture, such as (one or more) or Processor, Accelerated Processing Unit (APU), MxGPU, (one or more) processor, etc.; from The company's (one or more) A5-A12 and / or S1-S4 processors, from Snapdragon(s) from technology companies TM or Centriq TM processor, (One or more) Open Multimedia Applications Platform (OMAP) TM Processors; MIPS-based designs from MIPS Technologies Inc., such as the MIPS Warrior M-class, Warrior I-class, and Warrior P-class processors; ARM-based designs licensed from ARM Holdings plc, such as the ARM Cortex-A, Cortex-R, and Cortex-M series processors; and processors manufactured by Cavium TM Provided by the company In some implementations, the processor(s) 1152 may be part of a system on a chip (SoC), a system-in-Package (SiP), a multi-chip package (MCP), etc., where the processor(s) 1152 and other components are formed as a single integrated circuit, or a single package, such as from Edison TM or Galileo TM SoC Board. Other examples of processor(s) 1152 are mentioned elsewhere in this disclosure.

[0087] The system 1150 may include or be coupled to an acceleration circuit 1164, which may be embodied by one or more AI / ML accelerators, neural compute sticks, neuromorphic hardware, FPGAs, arrangements of GPUs, one or more SoCs (including programmable SoCs), one or more CPUs, one or more digital signal processors, dedicated ASICs (including programmable ASICs), PLDs (such as complex PLDs (CPLDs) or high complexity PLDs (HCPLDs)), and / or other forms of specialized processors or circuits designed to perform one or more specialized tasks. These tasks may include AI / ML processing (e.g., including training, inference, and classification operations), visual data processing, network data processing, object detection, rule analysis, and the like. In an FPGA-based implementation, the acceleration circuit 1164 may include logic blocks or logic architectures and other interconnected resources that may be programmed (configured) to perform various functions, such as the processes, methods, functions, and the like of the various embodiments discussed herein. In such an implementation, the acceleration circuit 1164 may also include a memory unit (e.g., EPROM, EEPROM, flash memory, static memory (e.g., SRAM, antifuse, etc.) for storing logic blocks, logic architectures, data, etc. in a LUT, etc.

[0088] In some implementations, the processor circuit 1152 and / or the acceleration circuit 1164 may include hardware elements specifically customized for machine learning and / or artificial intelligence (AI) functions. In these implementations, the processor circuit 1152 and / or the acceleration circuit 1164 may be or may include an AI engine chip that, once loaded with appropriate weighting and training code, can run many different kinds of AI instruction sets. Additionally, or alternatively, the processor circuit 1152 and / or the acceleration circuit 1164 may be or may include (one or more) AI accelerators, which may be one or more of the above-mentioned hardware accelerators designed for hardware acceleration of AI applications. As an example, these processors or accelerators may be a cluster of the following: artificial intelligence (AI) GPU, The company developed the tensor processing unit (TPU), The Real AI Processor (RAP TM ), Nervana provided by the company TM Neural Network Processor (NNP), Movidius TM Myriad TM XVision Processing Unit (VPU), based on PX TM GPU, Provided NM500 chip, Hardware3 provided by the company, Provided by Epiphany TM In some embodiments, the processor circuit 1152 and / or the acceleration circuit 1164 and / or the hardware accelerator circuit may be implemented as (one or more) AI acceleration coprocessors, such as Provided Hexagon 685DSP, PowerVR2NX Neural Net Accelerator (NNA) provided, The Neural Engine core inside the A11 or A12 Bionic SoC, The neural processing unit (NPU) within the HiSilicon Kirin 970 provided, etc. In some hardware-based implementations, the individual subsystems of the system 1150 can be operated by various AI acceleration coprocessors, AI GPUs, TPUs or hardware accelerators (e.g., FPGAs, ASICs, DSPs, SoCs, etc.), etc., which are configured with appropriate logic blocks, (one or more) bitstreams, etc. to perform their respective functions.

[0089] The system 1150 also includes a system memory 1154. Any number of memory devices may be used to provide a fixed amount of system memory. As an example, the memory 1154 may be or may include volatile memory, such as random access memory (RAM), static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), Dynamic Random Access Memory (DRAM) Dynamic Random Access Memory, ), and / or any other desired type of volatile memory device. Additionally or alternatively, the memory 1154 may be or may include a non-volatile memory, such as a read-only memory (ROM), an erasable programmable ROM (EPROM), an electrically erasable programmable (EEPROM), a flash memory, a non-volatile RAM, a ferroelectric RAM, a phase-change memory (PCM), a flash memory, and / or any other desired type of non-volatile memory device. Access to the memory 1154 is controlled by a memory controller. Individual memory devices may have any number of different package types, such as a single die package (SDP), a dual die package (DDP), or a quad die package (QDP). Any number of other memory implementations may be used, such as different types of dual inline memory modules (DIMMs), including but not limited to microDIMMs or MiniDIMMs.

[0090] The storage circuit 1158 provides persistent storage of information such as data, applications, operating systems, etc. In one example, the storage circuit 1158 can be implemented via a solid-state disk drive (SSDD) and / or a high-speed electrically erasable memory (commonly referred to as "flash memory"). Other devices that can be used for the storage circuit 1158 include flash memory cards, such as SD cards, microSD cards, XD picture cards, etc., and USB flash drives. In one example, the memory device may be or may include a memory device using chalcogenide glass, a multi-threshold level NAND flash memory, a NOR flash memory, a single-level or multi-level phase change memory (PCM), a resistive memory, a nanowire memory, a ferroelectric transistor random access memory (FeTRAM), an antiferroelectric memory, a memory including a magnetoresistive random access memory (MRAM) of memristor technology, a phase change RAM (PRAM), a resistive memory including a metal oxide substrate, an oxygen vacancy substrate and a conductive bridge random access memory (CB-RAM), or a spin transfer torque (STT)-MRAM, a device based on a spin electronic magnetic junction memory, a device based on a magnetic tunneling junction (MTJ), a device based on a domain wall (DW) and a spin orbit transfer (SOT), a memory device based on a thyristor, a hard disk drive (HDD) drive, HDD), micro HDD, or a combination of these, or any other memory. Memory circuit 1154 and / or storage circuit 1158 may also include and Three-dimensional (3D) cross-point (XPOINT) memory.

[0091] The memory circuit 1154 and / or the storage circuit 1158 are configured to store computing logic 1183 in the form of software, firmware, microcode, or hardware-level instructions to implement the techniques described herein. The computing logic 1183 may be employed to store a working copy and / or permanent copy of programming instructions, or data used to create programming instructions, for use with various components of the operating system 1150 (e.g., drivers, libraries, application programming interfaces (APIs), etc.), the operating system of the system 1150, one or more applications, and / or for implementing the embodiments discussed herein. The computing logic 1183 may be stored or loaded into the memory circuit 1154 as instructions 1182 or data used to create instructions 1182, and then accessed by the processor circuit 1152 for execution to implement the functions described herein. The processor circuit 1152 and / or the acceleration circuit 1164 access the memory circuit 1154 and / or the storage circuit 1158 via the interconnect (IX) 1156. The instructions 1182 direct the processor circuit 1152 to perform a particular sequence of actions or flow, for example, as described in the flowchart(s) and block diagram(s) regarding the operations and functions previously depicted. The various elements may be implemented by assembly instructions or a high-level language supported by the processor circuit 1152, which may be compiled into instructions 1188, or data used to create instructions 1188, for execution by the processor circuit 1152. A permanent copy of the programming instructions may be placed into a persistent storage device of the storage circuit 1258, for example, at the factory or in the field, via a distribution medium (not shown), via a communication interface (e.g., from a distribution server (not shown)), over the air (OTA), or any combination of these.

[0092] IX 1156 couples processor 1152 to communication circuitry 1166 for communication with other devices, such as a remote server (not shown), etc. Communication circuitry 1166 is a hardware element, or a collection of hardware elements, for communicating over one or more networks 1163 and / or with other devices. In one example, communication circuitry 1166 is or includes transceiver circuitry configured to implement wireless communication using any number of frequencies and protocols, such as Institute of Electrical and Electronics Engineers (IEEE) 802.11 (and / or its variants), IEEE 802.23.4, and / or Low energy ( low energy, BLE), , LoRaWAN TM(Long Range Wide Area Network), cellular protocols such as 3GPP LTE and / or Fifth Generation (5G) / New Radio (NR), etc. Additionally or alternatively, the communication circuit 1166 is or includes one or more network interface controllers (NICs) to enable wired communications using, for example, an Ethernet connection, a Controller Area Network (CAN), a Local Interconnect Network (LIN), DeviceNet, ControlNet, Data Highway+, or PROFINET, etc.

[0093] IX 1156 also couples processor 1152 to interface circuitry 1170 for connecting system 1150 to one or more external devices 1172. External devices 1172 may include, for example, sensors, actuators, positioning circuits (e.g., global navigation satellite system (GNSS) / Global Positioning System (GPS) circuits), client devices, servers, network appliances (e.g., switches, hubs, routers, etc.), integrated photonics devices (e.g., optical neural network (ONN) integrated circuits (ICs), etc.), and / or other similar devices.

[0094] In some optional examples, various input / output (I / O) devices may be present in or connected to the system 1150, which are referred to as input circuits 1186 and output circuits 1184. The input circuits 1186 and output circuits 1184 include one or more user interfaces designed to enable a user to interact with the platform 1150, and / or peripheral component interfaces designed to enable peripheral components to interact with the platform 1150. The input circuit 1186 may include any physical or virtual device for accepting input, including, in particular, one or more physical or virtual buttons (e.g., reset buttons), physical keyboards, keypads, mice, touch pads, touch screens, microphones, scanners, headsets, and the like. The output circuit 1184 may be included to show information or otherwise convey information, such as sensor readings, (one or more) actuator positions, or other similar information. Data and / or graphics may be displayed on one or more user interface components of the output circuit 1184. Output circuitry 1184 may include any number and / or combination of audio or visual displays, including, in particular, one or more simple visual outputs / indicators (e.g., binary status indicators (e.g., light emitting diodes (LEDs)) and multi-character visual outputs, or more complex outputs such as display devices or touch screens (e.g., liquid crystal displays (LCDs)). Display, LCD), LED display, quantum dot display, projector, etc.), where output of characters, graphics, multimedia objects, and the like is generated or produced from the operation of platform 1150. Output circuitry 1184 may also include speakers and / or other audio emitting devices, (one or more) printers, and the like. Additionally or alternatively, (one or more) sensors may be used as input circuitry 1184 (e.g., image capture devices, motion capture devices, etc.) and one or more actuators may be used as output device circuitry 1184 (e.g., actuators to provide tactile feedback, etc.). Peripheral component interfaces may include, but are not limited to, non-volatile memory ports, USB ports, audio jacks, power supply interfaces, and the like. In some embodiments, in the context of the present system, display or console hardware may be used to provide output to and receive input to an edge computing system; manage components or services of an edge computing system; identify the state of an edge computing component or service; or perform any other number of management or administrative functions or service use cases.

[0095] The components of the system 1150 may communicate via the IX 1156. The IX 1156 may include any number of technologies including ISA, extended ISA, I2C, SPI, point-to-point interface, power management bus (PMBus), PCI, PCIe, PCIx, UPI, Accelerator Link, CXL, CAPI, OpenCAPI, QPI, UPI, OPA IX, RapidIO TM System IX, CCIX, Gen-Z Consortium IX, HyperTransport Interconnect, NVLink, a Time-Trigger Protocol (TTP) system, a FlexRay system, PROFIBUS, and / or any number of other IX technologies provided. IX 1156 can be a proprietary bus used, for example, in a SoC-based system.

[0096] The number, capabilities, and / or capacity of the elements of the system 1150 may vary, depending on whether the computing system 1150 is used as a fixed computing device (e.g., a server computer in a data center, a workstation, a desktop computer, etc.) or a mobile computing device (e.g., a smart phone, a tablet computing device, a laptop computer, a gaming console, an IoT device, etc.). In various implementations, the computing device system 1150 may include one or more components of a data center, a desktop computer, a workstation, a laptop computer, a smart phone, a tablet device, a digital camera, a smart appliance, a smart home hub, a network appliance, and / or any other device / system that processes data.

[0097] The techniques described herein may be performed in part or in whole by software or other instructions provided in a machine-readable storage medium (e.g., memory). The software is stored as processor-executable instructions (e.g., instructions that implement any other process discussed herein). The instructions associated with the flow charts (and / or various embodiments) and executed to implement embodiments of the disclosed subject matter may be implemented as part of an operating system or a specific application, component, program, object, module, routine, or other sequence of instructions or organization of sequences of instructions.

[0098] The storage medium may be a tangible, non-transitory machine-readable medium, such as read-only memory (ROM), random access memory (RAM), flash memory devices, floppy disks and other removable disks, magnetic storage media, optical storage media (e.g., Compact Disk Read-Only Memory (CD ROMS), Digital Versatile Disk (DVD)), and the like.

[0099] The storage medium may be included in, for example, a communication device, a computing device, a network device, a personal digital assistant, a manufacturing tool, a mobile communication device, a cellular phone, a notebook computer, a tablet device, a game console, a set-top box, an embedded system, a TV (television), or a personal desktop computer.

[0100] Some non-limiting examples of various embodiments are given below.

[0101] Example 1 includes a device comprising: a group of resonators having different flipping temperatures; at least one driver; a group of switches for coupling the at least one driver to the group of resonators; and a control circuit coupled to the group of switches, wherein the control circuit is used to obtain a temperature from a temperature sensor, classify the temperature into a selected temperature range among a plurality of temperature ranges, and control the group of switches to couple the at least one driver to a first selected resonator among the group of resonators having a flipping temperature within the selected temperature range.

[0102] Example 2 includes the apparatus of Example 1, wherein each of the resonators has a flip temperature in a different temperature range among the plurality of temperature ranges.

[0103] Example 3 includes the apparatus of Example 1 or 2, wherein the plurality of temperature ranges are unequal in width and include a narrowest temperature range and an adjacent wider temperature range.

[0104] Example 4 includes the apparatus of any of Examples 1-3, wherein the at least one driver comprises a set of drivers, the set of drivers comprising a different driver for each resonator in the set of resonators.

[0105] Example 5 includes the apparatus of any of Examples 1-4, wherein the control circuit is to control the set of switches to couple the at least one driver to a second selected resonator in the set of resonators when the temperature crosses a transition temperature and a hysteresis band of the transition temperature.

[0106] Example 6 includes the apparatus of any of Examples 1 to 5, wherein each resonator in the set of resonators comprises a microelectromechanical system (MEMS) resonator, and the doping concentration is different for each MEMS resonator.

[0107] Example 7 includes the apparatus of any of Examples 1-5, wherein each resonator in the set of resonators comprises a quartz crystal resonator, and the cut angle of each quartz crystal resonator is different.

[0108] Example 8 includes the apparatus of any of Examples 1-6, wherein each resonator in the set of resonators comprises an oxide layer, and a thickness of each oxide layer is different.

[0109] Example 9 includes the apparatus of any of Examples 1 to 5, wherein each resonator in the set of resonators comprises a silicon-based piezoelectric resonator, and for each silicon-based piezoelectric resonator, a finger pitch to thickness (FP / t) ratio is different.

[0110] Example 10 includes the apparatus of any of Examples 1-9. Also included is at least one of an integrated circuit, a system on a chip, a system in a package, or a computing device, in which the set of resonators, the at least one driver, the set of switches, and the control circuit are provided.

[0111] Example 11 includes a device comprising: at least one driver for driving a first resonator having a first flip temperature and a second resonator having a second flip temperature, the second flip temperature being different from the first flip temperature; a set of switches coupled to the at least one driver; and a control circuit coupled to the set of switches, wherein the control circuit is used to: obtain a temperature from a temperature sensor; when the temperature is in a first temperature range corresponding to the first flip temperature, control the set of switches to couple the at least one driver to the first resonator; and when the temperature changes to a second temperature range corresponding to the second flip temperature, control the set of switches to couple the at least one driver to the second resonator.

[0112] Example 12 includes an apparatus as described in Example 11, wherein: the at least one driver includes a first driver and a second driver; and the control circuit is used to control the set of switches so that: when the temperature is in a first temperature range, the first driver is coupled to the first resonator; and when the temperature changes to the second temperature range, the set of switches is controlled to couple both the first driver and the second driver to the second resonator, and then couple the second driver to the second resonator, but the first driver is not coupled to the second resonator.

[0113] Example 13 includes the apparatus of Example 12, wherein, when the temperature changes to the second temperature range, the first driver injects a signal into the second resonator to achieve at least one of: accelerating a startup time of the second resonator, or locking a phase of the second resonator to a phase of the first resonator.

[0114] Example 14 includes the apparatus of Example 12 or 13, wherein the control circuit is to couple both the first driver and the second driver to the second resonator during a specified waiting period.

[0115] Example 15 includes the apparatus of any of Examples 11-14, wherein the at least one driver comprises a single driver, and the control circuit is to: when the temperature is in the first temperature range, control the set of switches to couple the single driver to the first resonator; and when the temperature changes to the second temperature range, control the set of switches to couple the single driver to both the first resonator and the second resonator, and then couple the single driver to the second resonator but not to the first resonator.

[0116] Example 16 includes the apparatus of Example 15, wherein the single driver injects a signal into the second resonator to achieve at least one of: accelerating a startup time of the second resonator, or locking a phase of the second resonator to a phase of the first resonator.

[0117] Example 17 includes a device comprising: a memory for storing instructions; and a processor for executing the instructions so as to: obtain a temperature from a temperature sensor; determine that the temperature is within a first temperature range; and based on determining that the temperature is within the first temperature range, control a set of switches to couple at least one driver to a first resonator in a set of resonators, wherein the first resonator has a flip temperature within the first temperature range.

[0118] Example 18 includes the apparatus of Example 17, wherein the set of resonators have different flipping temperatures.

[0119] Example 19 includes an apparatus as described in Example 17 or 18, wherein the processor is used to execute the instructions to control the set of switches to couple the at least one driver to a second resonator in the set of resonators when the temperature changes to a second temperature range, wherein the second resonator has a flipping temperature in the second temperature range.

[0120] Example 20 includes the apparatus of Example 19, wherein the processor is configured to execute the instructions to control the set of switches to simultaneously couple the at least one driver to both the first resonator and the second resonator when the temperature transitions from the first temperature range to the second temperature range.

[0121] Example 21 includes a method comprising: obtaining a temperature from a temperature sensor; determining that the temperature is within a first temperature range; and based on determining that the temperature is within the first temperature range, controlling a set of switches to couple at least one driver to a first resonator in a set of resonators, wherein the first resonator has a flip temperature within the first temperature range.

[0122] Example 22 includes the method of Example 21, wherein the set of resonators have different flipping temperatures.

[0123] Example 23 includes a method as described in Example 21 or 22, further comprising: when the temperature changes to a second temperature range, controlling the set of switches to couple the at least one driver to a second resonator in the set of resonators, wherein the second resonator has a flipping temperature in the second temperature range.

[0124] Example 24 includes the method of Example 23, further comprising controlling the set of switches to simultaneously couple the at least one driver to both the first resonator and the second resonator when the temperature transitions from the first temperature range to the second temperature range.

[0125] Example 25 includes the method as described in Example 23 or 24, further comprising: controlling the set of switches so that the at least one driver achieves at least one of the following: accelerating the start-up time of the second resonator, or locking the phase of the second resonator to the phase of the first resonator.

[0126] Example 26 includes a non-transitory machine-readable storage device including machine-readable instructions that, when executed, cause a processor or other circuit or computing device to implement a method as described in any of Examples 21-25.

[0127] Example 27 includes a computer program comprising instructions that, when executed by a computer, cause the computer to perform the method as described in any one of Examples 21-25.

[0128] In the detailed description herein, reference is made to the accompanying drawings, which form a part of this document, wherein like reference numerals designate like parts throughout, and in the accompanying drawings, embodiments that may be implemented are illustrated by way of illustration. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. Therefore, the following detailed description should not be understood in a limiting sense, and the scope of the embodiments is defined by the appended claims and their equivalents.

[0129] Various operations may be described in sequence as multiple discrete actions or operations in a manner that is most helpful for understanding the claimed subject matter. However, the order of description should not be interpreted as meaning that these operations must be order-dependent. These operations may not be performed in the order presented. The operations described may be performed in an order different from the described embodiments. Various additional operations may be performed and / or the operations described may be omitted in additional embodiments.

[0130] The terms "substantially," "close," "roughly," "approximately," and "about" generally refer to within + / -10% of a target value. Unless otherwise indicated, the use of ordinal adjectives "first," "second," and "third," etc., to describe common objects simply indicates that different instances of similar objects are referenced, and is not intended to imply that the objects so described must be in a given sequence in time, space, ranking, or in any other manner.

[0131] For purposes of this disclosure, the phrases "A and / or B" and "A or B" mean (A), (B), or (A and B). For purposes of this disclosure, the phrases "A, B, and / or C" mean (A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C).

[0132] The description may use the phrases "in one embodiment" or "in an embodiment", each of which may refer to one or more identical or different embodiments. In addition, the terms "including", "comprising", "having", etc. used in embodiments of the present disclosure are synonymous.

[0133] As used herein, the term "circuitry" may refer to, be a part of, or include an Application Specific Integrated Circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group), a combinational logic circuit, and / or other suitable hardware components that provide the described functionality. As used herein, a "computer-implemented method" may refer to any method performed by one or more processors, a computer system having one or more processors, a mobile device such as a smart phone (which may include one or more processors), a tablet device, a laptop computer, a set-top box, a game console, and the like.

[0134] The terms "coupled," "communicatively coupled," and their derivatives are used herein. The term "coupled" may mean that two or more elements are in direct physical or electrical contact with each other, may mean that two or more elements are in indirect contact with each other, but still cooperate or interact with each other, and / or may mean that one or more other elements are coupled or connected between the elements allegedly coupled to each other. The term "directly coupled" may mean that two or more elements are in direct contact with each other. The term "communicatively coupled" may mean that two or more elements are in contact with each other by means of communication, including by wires or other interconnections, by wireless communication channels or links, and the like.

[0135] References in the specification to "an embodiment", "one embodiment", "some embodiments" or "other embodiments" mean that the particular features, structures or characteristics described in connection with these embodiments are included in at least some embodiments, but not necessarily in all embodiments. The various appearances of "an embodiment", "one embodiment" or "some embodiments" do not necessarily all refer to the same embodiment. If the specification states that a component, feature, structure or characteristic "may", "might" or "could" be included, it is not necessary to include that component, feature, structure or characteristic. If the specification or claims refer to "an" element, it does not mean that there is only one of that element. If the specification or claims refer to "an additional" element, it does not exclude that there is more than one of that additional element.

[0136] In addition, features, structures, functions or characteristics may be combined in any appropriate manner in one or more embodiments. For example, the first embodiment may be combined with the second embodiment wherever the specific features, structures, functions or characteristics associated with the two embodiments are not mutually exclusive.

[0137] Although the present disclosure has been described in conjunction with its specific embodiments, many alternatives, modifications and variations of such embodiments will be apparent to those skilled in the art from the foregoing description. The embodiments of the present disclosure are intended to encompass all such alternatives, modifications and variations falling within the broad scope of the appended claims.

[0138] In addition, for simplicity of illustration and discussion, and in order not to obscure the present disclosure, known power / ground connections to integrated circuit (IC) chips and other components may or may not be shown in the given figures. In addition, the arrangement may be shown in block diagram form to avoid obscuring the present disclosure, and also taking into account the fact that the specific details of the implementation of such block diagram arrangements are highly dependent on the platform in which the present disclosure is to be implemented (i.e., such specific details should be fully within the scope of those skilled in the art). Where specific details (e.g., circuits) are set forth to describe example embodiments of the present disclosure, it should be clear to those skilled in the art that the present disclosure may be implemented without these specific details, or with variations of these specific details. The specification should therefore be considered illustrative, not restrictive.

[0139] An abstract is provided that will allow the reader to ascertain the nature and gist of the technical disclosure. The abstract is submitted with the understanding that it will not be used to limit the scope or meaning of the claims. The appended claims are hereby incorporated into the detailed description, with each claim standing on its own as a separate embodiment.

Claims

1. A device comprising: A set of resonators having different flipping temperatures; at least one drive; a set of switches for coupling the at least one driver to the set of resonators; as well as A control circuit coupled to the set of switches, wherein the control circuit is used to obtain a temperature from a temperature sensor, classify the temperature into a selected temperature range among a plurality of temperature ranges, and control the set of switches to couple the at least one driver to a first selected resonator among the set of resonators having a flip temperature within the selected temperature range.

2. The device according to claim 1, wherein: Each of the resonators has a switching temperature in a different temperature range among the plurality of temperature ranges.

3. The device according to claim 1 or 2, wherein: The plurality of temperature ranges are unequal in width and include a narrowest temperature range and an adjacent wider temperature range.

4. The device according to claim 1 or 2, wherein: The at least one driver includes a set of drivers including a different driver for each resonator in the set of resonators.

5. The device according to claim 1 or 2, wherein: The control circuit is configured to control the set of switches to couple the at least one driver to a second selected resonator in the set of resonators when the temperature crosses a transition temperature and a hysteresis band of the transition temperature.

6. The device according to claim 1 or 2, wherein: Each resonator in the set of resonators comprises a microelectromechanical system (MEMS) resonator, and the doping concentration is different for each MEMS resonator.

7. The device according to claim 1 or 2, wherein: Each resonator in the set of resonators comprises a quartz crystal resonator, and the cut angle of each quartz crystal resonator is different.

8. The device according to claim 1 or 2, wherein: Each resonator in the set of resonators includes an oxide layer, and a thickness of each oxide layer is different.

9. The device according to claim 1 or 2, wherein: Each resonator in the set of resonators comprises a thickness Lame mode silicon-based piezoelectric resonator, and for each thickness Lame mode silicon-based piezoelectric resonator, a finger pitch to thickness (FP / t) ratio is different.

10. The apparatus of claim 1 or 2, further comprising at least one of an integrated circuit, a system on a chip, a system in a package, or a computing device, in which the set of resonators, the at least one driver, the set of switches, and the control circuit are disposed.

11. An apparatus comprising: at least one driver for driving a first resonator having a first switching temperature and a second resonator having a second switching temperature, the second switching temperature being different from the first switching temperature; a set of switches coupled to the at least one driver; as well as a control circuit coupled to the set of switches, wherein the control circuit is configured to: Get the temperature from the temperature sensor; controlling the set of switches to couple the at least one driver to the first resonator when the temperature is in a first temperature range corresponding to the first flip temperature; and When the temperature changes to a second temperature range corresponding to the second switching temperature, the set of switches is controlled to couple the at least one driver to the second resonator.

12. The apparatus of claim 11, wherein: The at least one driver includes a first driver and a second driver; and The control circuit is used to control the set of switches so that: coupling the first driver to the first resonator when the temperature is in a first temperature range; and When the temperature changes to the second temperature range, the set of switches is controlled to couple both the first driver and the second driver to the second resonator, and then the second driver is coupled to the second resonator but the first driver is not coupled to the second resonator.

13. The device of claim 12, wherein: When the temperature changes to the second temperature range, the first driver injects a signal into the second resonator to achieve at least one of the following: accelerating a startup time of the second resonator, or locking a phase of the second resonator to a phase of the first resonator.

14. The device according to claim 12 or 13, wherein: The control circuit is used to couple both the first driver and the second driver to the second resonator during a specified waiting period.

15. The device according to claim 12 or 13, wherein: The at least one driver comprises a single driver, and the control circuit is used to: controlling the set of switches to couple the single driver to the first resonator when the temperature is in the first temperature range; and When the temperature changes to the second temperature range, the set of switches is controlled to couple the single driver to both the first resonator and the second resonator, and then the single driver is coupled to the second resonator but not to the first resonator.

16. The device of claim 15, wherein: The single driver injects a signal into the second resonator to at least one of: speed up a startup time of the second resonator, or lock a phase of the second resonator to a phase of the first resonator.

17. An apparatus comprising: Memory, used to store instructions; as well as A processor is used to execute the instructions so that: Get the temperature from the temperature sensor; determining that the temperature is within a first temperature range; and Based on determining that the temperature is in the first temperature range, a set of switches is controlled to couple at least one driver to a first resonator in a set of resonators, wherein the first resonator has a flip temperature in the first temperature range.

18. The device of claim 17, wherein: The set of resonators have different switching temperatures.

19. The device according to claim 17 or 18, wherein: The processor is used to execute the instructions to control the set of switches to couple the at least one driver to a second resonator in the set of resonators when the temperature changes to a second temperature range, wherein the second resonator has a flip temperature in the second temperature range.

20. The device of claim 19, wherein: The processor is used to execute the instructions to control the set of switches to simultaneously couple the at least one driver to both the first resonator and the second resonator when the temperature transitions from the first temperature range to the second temperature range.

21. A method comprising: Get the temperature from the temperature sensor; determining that the temperature is within a first temperature range; and Based on determining that the temperature is in a first temperature range, a set of switches is controlled to couple at least one driver to a first resonator in a set of resonators, wherein the first resonator has a flip temperature in the first temperature range.

22. A non-transitory machine-readable storage medium comprising machine-readable instructions which, when executed, cause a processor or other circuit or computing device to perform a method comprising: Get the temperature from the temperature sensor; determining that the temperature is within a first temperature range; and Based on determining that the temperature is in a first temperature range, a set of switches is controlled to couple at least one driver to a first resonator in a set of resonators, wherein the first resonator has a flipping temperature in the first temperature range, wherein the set of resonators have different flipping temperatures.

23. The non-transitory machine-readable storage medium of claim 22, wherein: The method further includes controlling the set of switches to couple the at least one driver to a second resonator in the set of resonators when the temperature changes to a second temperature range, wherein the second resonator has a flip temperature in the second temperature range.

24. The non-transitory machine-readable storage medium of claim 23, wherein: The method also includes controlling the set of switches to simultaneously couple the at least one driver to both the first resonator and the second resonator when the temperature transitions from the first temperature range to the second temperature range.

25. The non-transitory machine-readable storage medium of claim 23 or 24, wherein: The method further includes controlling the set of switches so that the at least one driver at least one of: accelerating a startup time of the second resonator, or locking a phase of the second resonator to a phase of the first resonator.

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