MEMS Oscillators Outperform LC Oscillators
Precision clock sources such as a XTAL, XO, Voltage Controlled Oscillator – VCXO, or TCXO require some type of resonator in order to supply an accurate, specific frequency. For decades, cost-effective clock sources have been manufactured with a quartz-crystal slice as the resonator element. However, over the past five years, there has been significant progress in the all-silicon clock timing alternative aimed at replacing the traditional quartz-crystal oscillator, especially in two technologies; MEMS (Micro-Electromechanical Systems) oscillators and the compensated LC oscillator. Both solutions are 100% silicon alternatives to the traditional quartz- crystal oscillators. With frequency stability of 100ppm over a relatively narrow 0°C to 70°C temperature range, the LC oscillator has been able to gain limited market share in some low-end consumer and computing applications where price dominates and stability and jitter performance is not critical. For all other applications where stability and jitter performance is critical, the MEMS oscillator is successfully taking more significant market share from the quartz-crystal incumbent. Once MEMS start-up innovator making an impact in the precision timing space is SiTime Corporation.SiTime’s all-silicon MEMS oscillators exceed all performance parameters compared to the LC oscillator. A basic key feature of any oscillator is frequency stability. When comparing standard oscillators, also called XO, the SiTime SiT8208 and SiT8209 guarantees less than 10 ppm (parts-per-million) over the -40°C to +85°C operating temperature range. This represents a 10x performance improvement compared to the LC oscillator’s 100ppm alternative. Furthermore, the SiTime SiT5001 TCXO family features 0.5 ppm stability over the -40°C to +85°C operating temperature range. This represents a level of performance that cannot be achieved by an LC oscillator.
SiTime’s MEMS oscillators simplify system designs and open the door to new applications. Though an LC oscillator will operate at any frequency within its range, they do not operate beyond approximately 200 MHz. SiTime’s single-ended LVTTL/CMOS compatible MEMS oscillators operate at any frequency up to 220 MHz and the differential oscillator family expands the frequency to 800 MHz. SiTime’s oscillators are all programmable to any frequency within their operating range as previously described.
In summary, the SiTime’s MEMS-based oscillators are optimized for applications that require some level of precision. They far exceed the performance of any LC oscillator and meet or exceed the performance of crystal-based oscillators.
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