A temperature-insensitive nonlinear silicon bulk acoustic oscillator
Abstract
We demonstrate a temperature-stable oscillator based on frequency Duffing in a degenerately doped silicon bulk acoustic wave resonator, transduced by a thin aluminum scandium nitride (AlScN) layer. The resonator operates in the cross-sectional Lamé (X-Lamé) mode at 64.7 MHz, exhibiting an ultra-high quality factor (Q) of 110 000 and a first-order temperature coefficient of frequency (TCF1) compensation. Additionally, the resonator provides amplitude-dependent frequency tunability through elastic Duffing. A secondary cross-sectional square-extensional (X-SE) mode at 92 MHz, with high linear temperature sensitivity, enables in situ temperature sensing. An oscillator is constructed with autonomous loop-gain control, leveraging the X-SE mode to compensate for the second-order TCF(TCF2) of the X-Lamé mode through nonlinear Duffing. This results in a frequency reference with a third-order temperature characteristic, featuring an insensitive region around the inflection points, with a TCF3 of 7 ppb/°C3. An overall frequency drift of ±1.88 ppb is measured for this weakly nonlinear oscillator over 1.47 °C temperature range near the 56 °C inflection point, showing an order of magnitude reduction in instability compared to the linear operation mode.
Article Details
Journal Info
Applied Physics Letters
American Institute of Physics
Authors (12)
S. Dabas
Electrical and Computer Engineering Department, University of Florida 2 , Gainesville, Florida 32611,
S. Mishra
B. Jabbari
Electrical and Computer Engineering Department, University of Michigan 1 , Ann Arbor, Michigan 48109,
D. Mo
Electrical and Computer Engineering Department, University of Florida 1 , Gainesville, Florida 32611,
R. Kundu
Electrical and Computer Engineering Department, University of Florida 1 , Gainesville, Florida 32611,
E. Ezike
Electrical and Computer Engineering Department, University of Florida 1 , Gainesville, Florida 32611,
S. Mondal
G. Baucom
Material Science and Engineering Department, University of Florida 3 , Gainesville, Florida 32611,
H. Kim
Z. Mi
Electrical and Computer Engineering Department, University of Michigan 1 , Ann Arbor, Michigan 48109,
B. Chatterjee
Electrical and Computer Engineering Department, University of Florida 1 , Gainesville, Florida 32611,
R. Tabrizian
Electrical and Computer Engineering Department, University of Michigan 1 , Ann Arbor, Michigan 48109,