Wireless Dosimeter: System-on-Chip Versus System-in-Package for Biomedical and Space Applications

Abstract

A new floating-gate (FG) MOSFET based wireless dosimeter system-in-package (SiP) is presented. This miniature and completely integrated wireless dosimeter SiP comprises a CMOS FG radiation sensor and transmitter (TX) in a low-temperature co-fired ceramic (LTCC) package. The design is very well suited to wireless transmission of radiation sensor data in radiotherapy and to Extra Vehicular Activity Radiation Monitoring (EVARM) in space. Two different solutions, namely system-on-chip (SoC) and SiP, are demonstrated. In the SoC, which is size and power efficient, the TX includes an on-chip loop antenna which also acts as the inductor for the VCO resonant tank circuit. The SiP solution has an LTCC antenna with optimized impedance to conjugate match the TX chip. The radiation sensor demonstrates a measured sensitivity of 5 mV/rad. The SoC module size is only 2 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , consumes 5.3 mW of power and delivers -0.9 dBm of radiated power, sufficient to communicate with a low noise receiver connected to an off-chip patch antenna placed 1.38 m away. The SiP design provides a larger communication range of 75 m at the cost of additional power consumption and size.