2-die wafer-level chip scale packaging enables the smallest TCXO for mobile and wearable applications

Real-time clocking for space-constrained mobile and wearable applications require low-power 32.768 kHz references with small form-factor and tight frequency stability, at a competitive price built in an ultra-high volume capable manufacturing process. Legacy 32 kHz quartz-based technology has reached the limits of miniaturization, performance and cost. In this work, a temperature compensated 32 kHz MEMS-based oscillator (TCXO), in a 1.55 mm × 0.85 mm × 0.55 mm form factor, with ±5 ppm frequency stability over -40°C to 85°C, will be presented. The combination of wafer-level chip scale packaging (WL-CSP) and silicon MEMS technology has enabled the smallest and best-in-class 32 kHz clocking solution for very high volume applications. The underlying MEMS system packaging and test technologies will be presented along with the electrical and reliability results.