C3.1 - A Time-Based Capacitive to Digital Converter With Fast Data Acquisitions and High Resolution
- Event
- SENSOR+TEST Conferences 2009
2009-05-26 - 2009-05-28
Congress Center Nürnberg - Band
- Proceedings SENSOR 2009, Volume I
- Chapter
- C3 - Sensor Electronics III
- Author(s)
- A. Heidary, G. Meijer - Technical University Delft, Delft, Netherlands
- Pages
- 297 - 300
- DOI
- 10.5162/sensor09/v1/c3.1
- ISBN
- 978-3-9810993-4-8
- Price
- free
Abstract
This paper presents an integrated interface with a fast data-accusation rate for capacitive sensor. Based on the results of an anlysis of the Charge-Transfer Process, the maximum frequency, for which the systematic errors are still within a certain limit, has been calculated. It is shown how the noise of the applied relaxation oscillator can be reduced by using a preamplifier with the minimum required bandwidth in front of the comparator. Further improvement is obtained by reducing the noise of integrator current in the applied relaxation oscillator. The interface has been designed for implementation in 0.7µm standard CMOS technology. Simulation results show that for a 5 pF sensor capacitance with a parasitic capacitance of 50 pF and a measurement time of 100 µs, a resolution of 14 bits can be achieved while power consumption is less than 5 mW.