A Discrete Implementation of a Semi-Floating Gate Amplifier for Resonating Sensor Front-End

The growing need of electronic sensors and transducers in modern and portable applications requires to research new design methods, which aim to lower the power consumption and reduce the occupied area of the sensor interface circuitry. In this work we present the implementation of a semi-floating gate amplifier (SFGA) to realize a compact and low power resonating sensor front-end. The prototype has been fabricated by using the commercial integrated circuit CD4007UBE and tested with a power supply of 3.3V. Measurement results show that the main trade-off of this circuit is between gain and bandwidth. The maximum values recorded for these two parameters are: 150VN and 2MHz respectively. The circuit has been tested with an input sinusoidal signal and then connected to a Butterworth Van Dike (BvD) load. This type of load is commonly used to mimic the behavior of a real resonating transducer. The average current absorbed by the amplifier during the normal operation is $6\mu A$ leading to a static power consumption of $19.8\mu W$. These values refer to a read-out frequency of 100Hz.