Jakub Gronicz

Design and fabrication of a tuning fork shaped voltage controlled resonator for low-voltage applications with additional tuning electrodes

In this work a silicon voltage controlled microelectromechanical tuning fork resonator with electrostatic actuation and separate frequency tuning electrodes is presented. The released device is fab ...

A 2µA temperature compensated mems-based real time clock with ±4 ppm timekeeping accuracy

This paper presents a MEMS-based real time clock with a temperature compensation system. The implemented circuit achieves a timekeeping accuracy of ±4 ppm over -40 °C... 85 °C temperature range. It is built using a 27 kHz silicon resonator, differential PTAT temperature sensor with a 2^nd order ΣΔADC, and a DSP block for temperature frequency compensation. The circuit is powered by a 1.8V supply and draws 2 μA current. The system has been implemented using a 0.18 μm CMOS process.

A 1.8 MHz MEMS-based oscillator with synchronous amplitude limiter

This paper describes the design and simulation of a MEMS-based oscillator using a synchronous amplitude limiter. The proposed solution does not require external control signals to keep the resonator drive amplitude within the desired range. In a MEMS oscillator the oscillation amplitude needs to be limited to avoid over-driving the resonator which could cause unwanted nonlinear behavior [1] or component failure. The interface electronics has been implemented and simulated in 0.35μm HV CMOS process. The resonator was fabricated using a custom rapid-prototyping process involving Focused Ion Beam masking and Cryogenic Deep Reactive Ion Etching.

Design and implementation of a 2A temperature-compensated MEMS-based real-time clock with 4ppm timekeeping accuracy

This paper presents the design and measurements of a temperature-compensated real-time clock based on a silicon resonator. The system exhibits timekeeping accuracy of 4ppm over the 40 to 85C temperature range. The current implementation is based on a TIA-based oscillator with a 27kHz MEMS resonator, a differential PTAT temperature sensor and a 2nd order ADC. The temperature compensation is performed by an on-chip DSP block. The system consumes 2A of current and operates at 1.8V nominal supply. The resonator operates off a 1.2V DC bias without the need for a charge-pump or providing an external higher DC voltage. The integrated electronics interface has been implemented using a standard 0.18m CMOS process.

A temperature sensor with 3σ inaccuracy of +0.5/-0.75 °C and energy per conversion of 0.65 μJ using a 0.18 μm CMOS technology

We present an integrated temperature sensor, which utilises bipolar transistors present in a 0.18pm CMOS process. A bipolar transistor is biased with two different current densities consecutively to have a voltage proportional to absolute temperature (PTAT). Two such bipolars are used to achieve a differential signal. The differential PTAT signal is fed to an incremental ΔΣ ADC to have temperature information in digital domain, which is then processed with an on-chip DSP block. The whole sensor can be put into power down mode after a conversion is done. The sensor operates in the temperature range from -40 °C to +85 °C. The energy per conversion is 0.65 μJ when the sensor output rate is at 3 conversions/s. The inaccuracy of the sensor is +0.5/-0.75 °C (3σ) after three point fitting.

A MEMS-based oscillator with synchronous amplitude control

This paper describes the design and simulation of a MEMS-based oscillator with a silicon tuning fork as frequency selective element. The interface electronics include a synchronous amplitude control circuit that allows for precise control of oscillation amplitude. The nominal oscillation frequency is 1.8 MHz. The structure has been implemented using a 0.35 μm High Voltage CMOS process and operates with a nominal supply of 3.3V.