ORTLAND, Ore.—Micro-electro-mechanical system (MEMS) resonators can now be integrated inside a semiconductor vendor's own plastic packages, eliminating the need for an external time base like a quartz crystal for real-time clocks. The world's first MEMS resonator for real-time clocks is being offered as a bare-die to CMOS chip makers by SiTime Corp.
"Semiconductor makers can wirebond our resonator die to their own chip inside a plastic package," said Piyush Sevalia, vice president of marketing at SiTime (Sunnyvale, Calif.). "We eliminate the need for an external quartz crystal for real-time clocks."
The quartz resonator market already tops $2 billion, according to SiTime, which claims that chip makers use them to create real-time clocks for microprocessors, microcontrollers, low power radios, sensor nodes, watches, SmartCards and application-specific standard products for portable, handheld and other consumer applications.
SiTime's novel MEMS resonator can be wirebonded to any CMOS die inside its package to eliminate external quartz crystals.
SiTime claims the low price and ten-times smaller size of its resonators will enable nearly any application using a quartz crystal for a real-time clock today to replace it with a cheaper, easier-to-use MEMS resonator that can be incorporated inside existing chip packages, thereby reducing a chip count. SiTime supplies all the necessary intellectual property (IP) for the amplification and compensation circuitry that conditions the raw resonator output for five parts-per-million (5 ppm) accuracy.
"Quartz requires all sorts of special tooling and packaging techniques making it more and more expensive if you integrate it with a plastic package," said Sevalia. "But for MEMS an inexpensive heterogeneous plastic package works just fine—our resonators is just another silicon die."
SiTime now markets MEMS resonators, oscillators and complete clock generator chips. The company has no announced customers yet, but claims to have already formed key partnerships with semiconductor makers for its new SiT1052 resonator.
The SiT1052 uses a basic clock frequency of 524 kHz that it divides by 16 to achieve a standard 32.768 kHz real-time resonator that can be combined with an SoC, ASIC or ASSP using wire-bonding or flip-chip plastic packaging. The half-millimeter square die—supplied on wafers with a known-good-die map—can withstand shocks 10-times greater than quartz crystals, according to SiTime, namely 70 Gs of vibration and up to 50,000 Gs of shock.