Get a detailed look at the top eight reasons to design with SiTime’s MEMs Oscillators over Quartz Resonators including ease of use, quality and reliability, and availability in any frequency. Watch the video now to explore the list of benefits MEMs Oscillators can offer your design.
However, oscillators which pair the resonator with an oscillator IC into one integrated timing device offer several benefits compared to crystals. In this module, we'll cover the top eight reasons to use MEMS Oscillators instead of quartz crystals.
Let's take a look at reason number one. Simplifying system design. On the surface, oscillator design using quartz crystals might seem straight forward, especially considering the maturity of this technology, but there are myriad of design parameters to consider in order to match the crystal to the oscillator circuit. Because an oscillator circuit requires close matching with the resonator to the oscillator circuit, crystal vendors cannot guarantee startup of the crystal.
By contrast, oscillators are completely integrated solution and the oscillator manufacturer matches the quartz resonator to the oscillator circuit. Startup is therefore guaranteed by SiTime. Reason number two, MEMS oscillators offer much better quality and reliability. Quality is very important, not only because company reputations are at stake but rework can be very costly.
Environmental stresses and outdoor applications must be especially robust. The process involved in tuning a crystal to a required frequency is complicated and is susceptible to contamination. In contrast, SiTime's MEMS devices use standard semiconductor batch techniques and the MEMS is vacuum-sealed with an Epi-Seal process to ensure the structure is completely encapsulated and free from contamination.
Reason number three. MEMS' low frequency oscillator solutions consume 65% less space on the board. SiTime's 1508 package oscillators are completely integrated solution and do not require external components such as power supply decoupling caps. The 1508 footprint is smaller than the smallest quartz crystal footprint. And when taking into account load capacitors that are needed for the 32 kHz quartz crystal, the total board area of the crystal solution is almost three times larger.
Reason Number four. Oscillators can drive multiple loads saving cost and further reducing board space. An oscillator is an active circuit with an output driver that is usually capable of driving two to three loads depending on the drive strength. This allows the oscillator to replace several crystals reducing system cost and board area.
Reason number five. MEMS oscillators are much less sensitive to EMI. Electromagnetic energy, which is common in most systems, can be picked up by exposed PCB traces which connect the quartz resonator to the IC containing the oscillator circuit. This noise can be coupled into the oscillator circuit and passed to the output, potentially adding jitter and noise to the system.
By contrast, MEMS oscillators have no exposed PCB connections between the MEMS resonator and IC containing the oscillator. And the bond wires that connect the MEMS resonator to the CMOS IC are extremely short. This results in MEMS oscillators having up to 11.3 dBm lower sensitivity than quartz resonators.
Reason number six. MEMS oscillators are much less sensitive to vibration. Vibration can be caused by things like environmental stresses such as wind, a cooling fan, or from general use of a vehicle. A key reason MEMS oscillators are resistant to shock and vibration is because MEMS resonators have approximately 1,000 to 3,000 times lower mass than quartz resonators. This graph shows the vibration sensitivity is greater with MEMS oscillators than 10 times that of quartz.
Reason number seven, MEMS oscillators are readily available in any frequency. Quartz suppliers are susceptible to longer lead times due to package constraint and the time it takes to cut the crystals. In contrast, the output frequency of MEMS oscillators the phase-locked loop to different multiplication values, enabling a very wide frequency range with six digits of accuracy. Samples can be available as early as one day with standard lead time on factory program parts being four to six weeks.
Reason number eight. Qualification efforts can be reduced with MEMS oscillators. This is important since component qualification can consume significant time and resources. SiTime products are based on a programmable platform which allows each device within a product family to generate a wide range of frequencies, supply voltages and stabilities. In contrast, each crystal frequency requires a different quartz blank. And if a design requires frequencies above 16 MHz, a different technology than fundamental mode quartz is often used.
In summary, MEMS oscillators offer many benefits relative to quartz resonators. Simple to design in, better reliability, and smaller package sizes are just a few key reasons to consider using MEMS oscillators in your design.