Injectable biotelemetry CMOS chip for identification and temperature measurement system

The development of a custom CMOS LSI circuit is described as a part of a telemetric device providing means of studying the relation between animal stress and body temperature on an automatic basis. The read only device is injectable and is capable of transponding on a close range information on both identity and temperature. The integrated circuit consists of two main parts. One part is a custom designed analog-to-digital convertor, which converts in the window ranging from 35 to 41 °C a PWM (Pulse Width Modulated) temperature signal [1][2] into a 6 bit code with an accuracy of 0.1 °C. The code memory and transponder form the second part of this circuit, which is entirely digital. Its programmable memory contains 42 bits of information code. On request, it will, woken up by a 132 kHz carrier, transmit a 50 bit code containing the temperature and identification data to a nearby receiver at 66 kHz, having a range of 0.5 m. Special merits of the circuit are low power consumption (30 ¿W during conversion, 2.4 mW during transmission) and low operating voltage (3 V).