Chill out with MEMS TCXOs at high temperatures : Page 3 of 4

June 09, 2020 //By Gary Giust, of SiTime Corp.
Chill out with MEMS TCXOs at high temperatures
Gary Giust, of SiTime Corp. (Santa Clara, Calif.), explains why a MEMS-based timing device fulfilling the role of a temperature-compensated crystal oscillator (TCXO) is a good choice for high-temperature applications that demand reliability.

The physics of a MEMS resonator is very different to that of quartz. Its inherent qualities offer several advantages over quartz TCXOs in outdoor mounted electronic systems.

The first is availability. MEMS precision TCXOs rated up to +105°C ambient temperature are readily available. Figure 2 shows how typical quartz OCXOs' stability falls sharply above 85°C. However, the TCXO devices remain stable well above their maximum rated operating ambient temperature range of 105°C, extending all the way up to +125°C.

The MEMS TCXO also provides high stability and improved dynamic performance in extreme conditions caused by limited air flow, temperature changes, mechanical shock, vibration, noise from power supplies, and EMI.

Figure 2: Comparison of stability beyond rated temperature of three typical OCXOs versus multiple SiTime Elite TCXOs

MEMS TCXOs also do not experience frequency jumps and activity dips when temperatures rise. Figure 3 shows the “graceful degradation” of MEMS TCXOs operating outside of their maximum temperature range.

Figure 3: The graceful degradation of production-trimmed precision MEMS TCXOs ensures operation during extremes of temperatures.

The graph shows the frequency stability-over-temperature performance of an SiT5356 ±100 ppb MEMS TCXO as it operates from -60°C and up to +125°C; far beyond its rated operating ambient temperature range (-40°C to +105°C).

Stability remains similar - only slightly reduced - enabling the MEMS oscillator to continue to function until a later time when the ambient temperature drops back within the normal operating range.

Finally, because it is 100 percent silicon, a MEMS resonator is inherently higher quality and more reliable than quartz-based devices. These characteristics increase the quality and reliability of the networks in which they are deployed.

Next: Conclusions

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