US-12627258-B2 - Dual resonator structure for temperature-compensated oscillators, including related apparatuses

US12627258B2US 12627258 B2US12627258 B2US 12627258B2US-12627258-B2

Abstract

An apparatus comprises a micromechanical system including a semiconductor body. The semiconductor body comprises a first resonator, a second resonator, and a supporting portion. The first resonator is to resonate at a first resonating frequency that is generally frequency-stable over a predetermined temperature range. The second resonator is to resonate at a second resonating frequency that is generally linearly decreasing or increasing as temperature increases over the predetermined temperature range. The supporting portion is to support both the first resonator and the second resonator.

Inventors

Seungbae Lee

Assignees

MICROCHIP TECHNOLOGY INCORPORATED

Dates

Publication Date: 20260512
Application Date: 20240829

Claims (20)

1 . An apparatus comprising: a microelectromechanical system including a semiconductor body, the semiconductor body comprising: a first resonator, the first resonator including first resonating portions to resonate at a first resonating frequency that is generally frequency-stable over a predetermined temperature range; a second resonator, the second resonator including second resonating portions to resonate at a second resonating frequency that is generally linearly decreasing or increasing as temperature increases over the predetermined temperature range; and a supporting portion, the supporting portion to support both the first resonator and the second resonator, the supporting portion including a first connecting portion to the first resonator and a second connecting portion to the second resonator, the first connecting portion surrounding respective portions of respective perimeters of the first resonating portions of the first resonator, the second connecting portion surrounding respective portions of respective perimeters of the second resonating portions of the second resonator.
2 . The apparatus of claim 1 , wherein: the first resonator has a first temperature coefficient of frequency; and the second resonator has a second temperature coefficient of frequency, the second temperature coefficient of frequency different from the first temperature coefficient of frequency.
3 . The apparatus of claim 1 , wherein: the first resonator comprises a reference resonator; the second resonator comprises a temperature sensing resonator; and the supporting portion mechanically and thermally couples the first resonating portions of the first resonator and the second resonating portions of the second resonator.
4 . The apparatus of claim 1 , wherein the semiconductor body comprises: at least one first drive electrode of the first resonator; at least one first sense electrode of the first resonator; at least one second drive electrode of the second resonator; and at least one second sense electrode of the second resonator.
5 . The apparatus of claim 1 , wherein: respective ones of the first resonating portions of the first resonator have a first shape and a first size; respective ones of the second resonating portions of the second resonator have a second shape and a second size; the second shape is substantially the same as the first shape; and the second size is substantially the same as the first size.
6 . The apparatus of claim 5 , wherein the first resonator and the second resonator are substantially symmetric about a lateral axis of the semiconductor body.
7 . The apparatus of claim 1 , wherein the first resonator and the second resonator are orientated at a differential orientation angle with respect to one another.
8 . The apparatus of claim 7 , wherein: the first resonating portions of the first resonator resonate at the first resonating frequency to exhibit a first acoustic wave propagation in a first direction; the second resonating portions of the second resonator resonate at the second resonating frequency to exhibit a second acoustic wave propagation in a second direction; and the first direction and the second direction are non-parallel.
9 . The apparatus of claim 1 , comprising: a single supporting anchor to anchor the semiconductor body, the single supporting anchor in substantially a center of the supporting portion.
10 . The apparatus of claim 1 , wherein the first connecting portion surrounds about twenty-five (25) percent or more of the respective portions of the respective perimeters of the first resonating portions of the first resonator, and the second connecting portion surrounds about twenty-five (25) percent or more of the respective portions of the respective perimeters of the second resonating portions of the second resonator.
11 . The apparatus of claim 10 , wherein the first resonating frequency exhibits a change or delta in frequency over the predetermined temperature range that is less than a predetermined amount.
12 . The apparatus of claim 11 , wherein the predetermined amount is 600 parts-per-million over the predetermined temperature range of −40-90° C.
13 . The apparatus of claim 1 , wherein the second resonating portions of the second resonator are to resonate at the second resonating frequency that is generally linearly decreasing as temperature increases over the predetermined temperature range.
14 . The apparatus of claim 1 , wherein the semiconductor body comprises a single crystal silicon.
15 . The apparatus of claim 1 , comprising: a single die comprising the semiconductor body.
16 . The apparatus of claim 1 , wherein respective ones of the first resonator and the second resonator comprise a dual-ring resonator including a first ring, a second ring, and a coupling beam to couple the first ring and the second ring.
17 . The apparatus of claim 1 , wherein respective ones of the first resonator and the second resonator comprise a ring resonator, a disc resonator, a square plate resonator, a clamped-clamped resonator, a cantilever resonator, a fixed-fixed beam resonator, and a comb drive resonator.
18 . An apparatus comprising: an oscillator comprising: a microelectromechanical system including a semiconductor body, the semiconductor body comprising: a first resonator, the first resonator including first resonating portions to resonate at a first resonating frequency that is generally frequency-stable over a predetermined temperature range; at least one first drive electrode of the first resonator; at least one first sense electrode of the first resonator; a second resonator, the second resonator including second resonating portions to resonate at a second resonating frequency that is generally linearly decreasing or increasing as temperature increases over the predetermined temperature range; at least one second drive electrode of the second resonator; at least one second sense electrode of the second resonator; and a supporting portion to support both the first resonator and the second resonator, the supporting portion including a first connecting portion to the first resonator and a second connecting portion to the second resonator, the first connecting portion surrounding respective portions of respective perimeters of the first resonating portions of the first resonator, the second connecting portion surrounding respective portions of respective perimeters of the second resonating portions of the second resonator.
19 . The apparatus of claim 18 , wherein the microelectromechanical system is on a first die, the apparatus comprising: the oscillator comprising: an electronic circuitry, the electronic circuitry on a second die attached to the first die, the electronic circuitry comprising: a first drive circuitry, the first drive circuitry to generate a first drive signal to drive the first resonator via the at least one first drive electrode, the first drive signal having a first drive frequency; a second drive circuitry, the second drive circuitry to generate a second drive signal to drive the second resonator via the at least one second drive electrode, the second drive signal having a second drive frequency; a digital converter circuitry, the digital converter circuitry to receive a first sense signal from the first resonator via the at least one first sense electrode and to convert the first sense signal into first digital temperature data, the first sense signal having a first sense signal frequency and the first digital temperature data to represent a first temperature corresponding to the first sense signal frequency; and the digital converter circuitry to receive a second sense signal from the second resonator via the at least one second sense electrode and to convert the second sense signal into second digital temperature data, the second sense signal having a second sense signal frequency and the second digital temperature data to represent a second temperature corresponding to the second sense signal frequency.
20 . The apparatus of claim 19 , comprising: the electronic circuitry comprising: a temperature compensation circuitry, the temperature compensation circuitry to generate an adjustment signal at least partially based on a ratio of changes in the first temperature represented by the first digital temperature data and the second temperature represented by the second digital temperature data, respectively; and a phase-lock-loop circuitry, the phase-lock-loop circuitry to adjust the first sense signal frequency at least partially based on the adjustment signal for producing a temperature-compensated oscillator signal.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit under 35 U.S.C. § 119 (e) of U.S. Provisional Patent Application No. 63/580,247, filed Sep. 1, 2023, and titled “Dual Resonator Structure for Temperature-Compensated Oscillators,” the entire disclosure of which is hereby incorporated herein by reference. The subject matter of this application is also related to U.S. patent application Ser. No. 18/818,810, filed Aug. 29, 2024, the entire disclosure of which is hereby incorporated herein by reference. TECHNICAL FIELD Examples relate, generally, to resonators for timing applications. More specifically, some examples relate to microelectromechanical (MEMS) resonators for temperature-compensated oscillators, without limitation. BACKGROUND Mechanically vibrating devices are used in communication systems, as well as other systems that require a frequency reference, in a variety of applications and operational contexts. Although quartz-based resonant devices and other acoustic devices are widely used in electronic systems, traditional quartz crystal oscillators are relatively large in comparison to other components in these systems. This is especially true in applications where miniaturization is required. Due to their mechanical nature and specific fabrication processes, these devices may be more challenging to integrate with their associated electronic circuitry. Some integrated circuits (ICs) with precise timing requirements rely on an external crystal or a crystal oscillator module. On the other hand, silicon-based microelectromechanical systems (MEMS) are attractive for use as compact, single-chip integrated or directly integrated frequency references. BRIEF DESCRIPTION OF THE DRAWINGS While this disclosure concludes with claims particularly pointing out and distinctly claiming specific examples, various advantages of examples within the scope of this disclosure may be more readily ascertained from the following description when read in conjunction with the accompanying drawings, in which: FIG. 1 is a block diagram of an apparatus including a microelectromechanical system (MEMS) comprising a semiconductor body on a MEMS die, where the semiconductor body comprises a first resonator, a second resonator, and a supporting portion to support both the first resonator and the second resonator (“dual resonator structure”), according to one or more examples; FIG. 2 is a perspective view of an example of the apparatus of FIG. 1, where respective ones of the first resonator and the second resonator comprise a dual-ring resonator having first and second rings, according to one or more examples; FIG. 3 is a top-down view of the apparatus of FIG. 2, according to one or more examples; FIG. 4A is a top-down view of the apparatus of FIGS. 2 and 3, depicting a vibrating or resonating state of the first resonator that results in a first acoustic wave propagation in a first direction, according to one or more examples; FIG. 4B is a top-down view of the apparatus of FIGS. 2 and 3, depicting a vibrating or resonating state of the second resonator that results in a second acoustic wave propagation in a second direction, according to one or more examples; FIG. 5A is a top-down view of a schematic layout of the apparatus of FIGS. 2 and 3, according to one or more examples; FIG. 5B is a close-up, top-down view of a portion of the schematic layout of the apparatus of FIG. 5A, indicating gaps that may separate resonating portions or rings of the first resonator from surrounding electrode material; FIG. 6 is a perspective, partial cross-sectional view of a portion of the apparatus associated with the first resonator taken along a line A-A′ of FIG. 5B; FIG. 7 is a cross-sectional view of a portion of the apparatus associated with the first resonator also taken along a line A-A′ of FIG. 5B; FIG. 8 is a schematic block diagram of an apparatus comprising an oscillator including a dual resonator structure having a resonator and a second resonator, according to one or more examples; FIG. 9 is a block diagram of an oscillator that is known to the inventor of this disclosure; FIG. 10A is a graph of a first plot representing a relationship between a temperature coefficient of frequency (TCf) and a doping concentration for the first resonator (e.g., the reference resonator, without limitation), and a second plot representing a relationship between a frequency variation and the doping concentration for the first resonator, according to one or more examples; FIG. 10B is a graph of a plot representing a relationship between a frequency change and a temperature for the first resonator; FIG. 11A is a graph of a first plot representing a relationship between a TCf versus the doping concentration for the second resonator (e.g., temperature sensing resonator, without limitation), and a second plot representing a relationship between a frequency variation and the doping concentration for the second resonator, according to one or mor