A versatile single/differential quasi-digital converter for portable sensing applications

This paper presents a new high performance 1.2 V - 0.18 μm CMOS voltage-to-frequency converter (VFC) that can be used either in single or differential mode to digitize sensor read-out signals in wireless sensor network applications. The proposed VFC works properly over the entire input range with output frequencies ranging between 0.0 and 0.9 MHz, which allows the sensor node microcontroller optimally perform the final digitalization. It achieves high linearity (0.009% linearity error) with low power consumption (72 μW) for a temperature range of -40 to 120°C) and supply voltage variations of 30%.