VOLUME 1, ISSUE 10, DECEMBER 2012

Abstract: In the latest portable two-way radio design, processors have been widely used as the main ‘heart’ to control the whole operations of the radio during idle, receiving (Rx) and transmit (Tx) modes instead of Applications Specific Integrated Circuits (ASIC). By integrating processor into the design, various powerful applications could be offered to the customers but at the cost of additional power consumptions even if the radio is at idle mode. Ultimately, processors are well known to be more power hungry compared to ASIC. This will post even greater challenge for the radio designers to meet the battery life specification, in which is an essential & critical customer requirement for communications during critical public safety or rescue missions. This paper attempts to investigate the fundamental significant factors that determine the power consumptions of the CMOS based processor. HSPICE current consumption simulations with various combinations of voltage, frequency, load capacitance and temperature values are performed on a modeled CMOS buffer circuit, the simplest logic circuit available in a processor design. Design of Experiments (DOE) method was used to analyze the measured current consumptions at various combinations, determine the significant factors related to current consumptions of CMOS buffer circuit and derive the current consumption transfer function for the buffer circuit. Current consumptions saving of up to 88.30 % was found out to be feasible in CMOS based design by addressing the key significant factors identified in the earlier DOE analysis. Once all the significant factors affecting the current consumption of CMOS based design are known, various related power saving features that are offered by the processors in the market will be discussed for adoption into portable two way radio design.

Keywords: CMOS, Current consumption, DOE, power.