Wireless system -on -chip sensor design for radiotherapy applications

This research is focused on the development of a novel miniaturized wireless dosimeter for cancer patient radiotherapy. During radiotherapy treatment, cancerous region of the body are exposed to high energy radiation. The knowledge of the exact amount of radiation penetrating the body is essential for a successful treatment. Too little radiation will be ineffective and too much can seriously harm the patient. The device used to measure the radiation dose is called a dosimeter. Present dosimeters have numerous limitations. Most are either limited in sensitivity or are susceptible to temperature and environmental variations, thus leading to inaccurate measurements. The existing dosimeters are wired, large in size, non-wearable and require high operating voltages. The wires deflect and scatter the radiation away from the targeted region during the irradiation process. To alleviate the abovementioned problems, a miniaturized wireless dosimeter System on Chip (SoC) solution is proposed.;To complete the wireless sensor system, a novel miniaturized receiver (RX) SoC has been designed. This is the smallest reported 5 GHz receiver (1.3 mm2) with an on-chip antenna in a standard IBM 0.13 μm CMOS process. It incorporates a low noise amplifier (LNA) with unique on-chip antenna impedance matching and a fully differential Delay Lock Loop (DLL) circuit. The miniaturization is achieved by placing the circuits inside a meandered antenna. The co-design methodology for on-chip antenna and LNA is described. Such a methodology resulted in very wideband impedance matching without the need for matching elements. The LNA is completely differential, consumes only 8 mW of power with a noise figure of 2.9 dB and provides a gain of 21 dB. The total gain of the antenna and receiver chip is -15 dB and it consume 14 mW of power. Design tradeoffs and measurement challenges of the SoC RX are described in detail.;The results of this research demonstrate the feasibility of low power wireless radiation sensors, and provide a basis for the development of other wireless biomedical devices.;The foremost requirement of a wireless dosimeter is a miniaturized, highly sensitive and reliable low power radiation sensor. In this dissertation new radiation sensors have been designed in standard low cost CMOS process (DALSA 0.8 μm CMOS). Several innovative radiation sensors have been realized to (i) improve sensitivity, (ii) reduce operating voltage, (iii) reject environmental and process changes, and (iv) enable wireless operation. A fully integrated SoC dosimeter having radiation sensors with signal processing and readout circuits fabricated on the same chip has been demonstrated for the first time. The sensitivity of the sensor has been improved by more than 10% by reducing the capacitance to the floating gate (FG) and using elevated metal shielding. Both the enhanced sensitivity of the sensors and the presence of an identical FG reference permit low voltage operation. The radiation sensors have been characterized for sensitivity, and stability using measurements, simulations and mathematical analysis. The use of an identical FG reference also eliminates the effects of environmental and process changes. The dosimeter has been designed for integration with a transmitter (TX) chip to transmit the sensor data in a wireless fashion. The integrated SPE on the sensor chip conditions the signal and converts it to the desired control signal that modulates the TX waveform. The entire wireless dosimeter is 0.5 cm2 in size and consumes 5.3 mW of power.