A novel PLL-based sensor interface for resistive pressure sensors

Due to the ongoing trend towards smaller technologies, time-/frequency-to-digital conversion is gaining popularity. It benefits from the improved timing resolution in new technologies whereas voltage processing suffers from reduced signal swing and non-idealities. In this work, a new PLL-architecture for digitization of sensor signals is described which fully exploits the benefits of frequency processing. Its working principle and relevance is explored with the help of system level simulations. Thereafter a test-case for resistive sensors is implemented in XFAB 0.35u CMOS technology. An accuracy of 72 dB at 10000 samples/s is achieved.