A monitoring circuit for accurately monitoring a voltage level from each of a plurality of battery cells of a battery pack includes an analog to digital converter and a processor. The transmitter includes a digital modulator adapted to provide a digital modulated RF signal based on a multi-bit representation of data and a multi-bit representation of a carrier wave. The SOI substrate is pressured against the substrate by using a pressurizing member and the plurality of sealing windows of the SOI substrate is bonded to the substrate via a low melting point glass member arranged around the plurality of semiconductor elements. A bulb either is self-enclosed or an envelope sealed by a window or lens covering the chamber aperture.