This paper describes the first precision 32kHz low-power MEMS-based oscillator in production. The primary goal is to provide a small form-factor oscillator (1.5 x 0.8 mm 2) for use as a crystal replacement in space-constrained mobile devices. The oscillator generates an output frequency of 32.768kHz and its binary divisors down to 1Hz. The frequency stability over the industrial temperature range (-40°C to 85°C) is ±100ppm as an oscillator (XO) or ±3ppm with optional calibration as a temperature compensated oscillator (TCXO). Supply currents are 0.9µA for the XO and 1.0µA for the TCXO at supply voltages from 1.4V to 4.5V. The MEMS resonator is a capacitively-transduced tuning fork at 524kHz. The circuitry is fabricated in 180-nm CMOS and includes low power sustaining circuit, fractional-N PLL, temperature sensor, digital control, and low swing driver.

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In a normally functioning eye, the iris controls the pupil diameter to regulate the amount of light reaching the retina. Various iris deficiencies exist, manifesting as defects in the iris or an absence of one which result in too much light reaching the retina. Some iris deficiencies such as aniridia or leiomyoma can be mitigated with fixed or adaptive artificial irises [1]. As an alternative, adaptive transparency glasses may also alleviate this situation, however both solutions do not mimic the other normal functionality of the natural iris: adaptive aperture. To address this, we developed a fully encapsulated, self-contained artificial iris embedded in a smart contact lens. The control ASIC of the contact lens is developed in 0.18 µm 16 V BCD TSMC and has a typical power consumption of 1.9 µW from a 3 V supply voltage at office light condition.

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