Dual resonator structure for oven-controlled MEMS oscillators, including related apparatuses
An apparatus comprises a microelectromechanical system (MEMS) including a semiconductor body. The semiconductor body comprises a first resonator, a second resonator, a supporting portion, and one or more heating elements of a heater. 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. The one or more heating elements of the heater are on, or in, the supporting portion.
1 . An apparatus comprising:
a microelectromechanical system (MEMS) including a semiconductor body, the semiconductor body comprising:
a first resonator, the first resonator to resonate at a first resonating frequency that is generally frequency-stable over a predetermined temperature range;
a second resonator, the second resonator to resonate at a second resonating frequency that is generally linearly decreasing or increasing as temperature increases over the predetermined temperature range;
a supporting portion, the supporting portion to support both the first resonator and the second resonator, the supporting portion adjacent and interposed between the first resonator and the second resonator; and
one or more heating elements of a heater distributed on, or in, the supporting portion.
2 . The apparatus of claim 1 , comprising:
a thermally-insulating enclosure of an oven, the thermally-insulating enclosure containing the first resonator, the second resonator, and the supporting portion including the one or more heating elements of the heater.
3 . The apparatus of claim 2 , wherein the apparatus comprises an oven-controlled MEMS timing device.
4 . 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.
5 . 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 resonator and the second resonator.
6 . The apparatus of claim 1 , wherein the second resonator to resonate at a second resonating frequency that is generally linearly decreasing as temperature increases over the predetermined temperature range.
7 . 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.
8 . The apparatus of claim 7 , comprising:
at least first and second conductive vias coupled to the one or more heating elements.
9 . The apparatus of claim 1 , wherein:
the first resonator comprises an outer portion of the semiconductor body, and
the second resonator comprises a central portion of the semiconductor body.
10 . The apparatus of claim 9 , wherein:
the first resonator comprises a multi-beam resonator, and
the second resonator comprises a multi-ring resonator.
11 . The apparatus of claim 1 , wherein the semiconductor body comprises a single crystal silicon.
12 . The apparatus of claim 1 , comprising:
a single die comprising the semiconductor body.
13 . An apparatus comprising:
an oven-controlled microelectromechanical system (MEMS) timing device comprising:
a microelectromechanical system including a semiconductor body, the semiconductor
body comprising:
a first resonator, the first resonator comprising an outer portion of the semiconductor body, the first resonator 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 comprising a central portion of the semiconductor body, the second resonator 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;
a supporting portion to support both the first resonator and the second resonator; and
one or more heating elements of a heater on, or in, the supporting portion.
14 . The apparatus of claim 13 , comprising:
a thermally-insulating enclosure of an oven, the thermally-insulating enclosure containing the first resonator, the second resonator, and the supporting portion including the one or more heating elements of the heater.
15 . The apparatus of claim 14 , comprising:
at least first and second conductive vias coupled to the one or more heating elements of the heater.
16 . The apparatus of claim 15 , wherein the microelectromechanical system is on a first die, the apparatus comprising:
the oven-controlled MEMS timing device 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.
17 . The apparatus of claim 13 , wherein the supporting portion is adjacent and interposed between the first resonator and the second resonator.
18 . The apparatus of claim 16 , comprising:
the electronic circuitry comprising:
a temperature control circuitry, the temperature control circuitry to control a voltage or current of the one or more heating elements to maintain a temperature of the semiconductor body at a predetermined temperature, and to adjust the voltage or current of the one or more heating elements 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.
19 . The apparatus of claim 18 , wherein the predetermined temperature comprises a turnover temperature of the first resonator.
20 . The apparatus of claim 13 , wherein:
the first resonator having a first temperature coefficient of frequency, and
the second resonator having a second temperature coefficient of frequency, the second temperature coefficient of frequency different from the first temperature coefficient of frequency.
21 . The apparatus of claim 13 , 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 resonator and the second resonator.
22 . The apparatus of claim 13 , the second resonator to resonate at the second resonating frequency that is generally linearly decreasing as temperature increases over the predetermined temperature range.
23 . The apparatus of claim 13 , wherein:
a temperature offset between the first resonator and the second resonator is zero or negligible, and
a thermal gradient between the first resonator and the second resonator is zero or negligible.
24 . The apparatus of claim 13 , wherein:
the first resonator comprises a multi-beam resonator, and
the second resonator comprises a multi-ring resonator.
25 . The apparatus of claim 16 , wherein the semiconductor body comprises a single crystal silicon.
26 . An apparatus comprising:
an oven-controlled microelectromechanical system (MEMS) timing device comprising:
a microelectromechanical system including a semiconductor body, the semiconductor body comprising:
a multi-beam resonator, the multi-beam resonator to resonate at a first resonating frequency that is generally frequency-stable over a predetermined temperature range, the multi-beam resonator comprising an outer portion of the semiconductor body;
a multi-ring resonator, the multi-ring resonator to resonate at a second resonating frequency that decreases as temperature increases over the predetermined temperature range, the multi-ring resonator comprising a central portion of the semiconductor body;
a supporting portion to support both the multi-beam resonator and the multi-ring resonator; and
one or more heating elements of a heater on, or in, the supporting portion.
27 . The apparatus of claim 26 , comprising:
a thermally-insulating enclosure of an oven, the thermally-insulating enclosure containing the multi-beam resonator, the multi-ring resonator, and the supporting portion including the one or more heating elements of the heater.
28 . The apparatus of claim 27 , comprising:
at least first and second conductive vias coupled to the one or more heating elements of the heater.