National Conference on Innovative Paradigms in Engineering & Technology (NCIPET-2012) Proceedings published by International Journal of Computer Applications® (IJCA) 15 Mixed Signal Interface Chip for Wearable Healthcare System Chandrakant Ragit Sanjay Badjate HOD, Eletronics &Telecom’n Dept. Professor & Vice-Principal of Cummins COE for Women, Nagpur SBJIT, Nagpur ABSTRACT Smart sensors, which are created by combining sensing materials with integrated circuitry are being considered for several biomedical application such as a glucose level ,temperature ,Ecg ,etc. Practical usability of the majority of current wearable body sensor systems for multiple parameter physiological signal acquisition is limited by the multiple physical connections between sensors and the data-acquisition modules. In order to improve the user comfort and enable the use of these types of systems on active mobile subjects, a wireless body sensor system that incorporates multiple sensors on a single node is proposed [10]. The system must be suitable for longer-term monitoring of the subjects, such as continuous wear and autonomous operation up to several days without replacement of the power source. Thus power consumption is a major challenge in these applications. The sensing and read-out of the signals may draw a significant part of the power budget in today’s sensor nodes in WBAN, especially when the number of signals or channels is increasing. Thus, reducing the power required for signal extraction is an important challenge. Many system-on-chip (SoC) solutions have been presented for multiparameter sensor systems, but these do not offer application engineers the freedom of tailoring modules in their system to suit their specific application. Keywords: sensors,WBSN,health care . 1. INTRODUCTION Recently, the Wireless Body Sensor Network (WBSN) system has been a popular topic for researchers. Typical WBSN applications include the medical and health applications such as vital signs monitoring, fitness and medical care [1][2][3][4]. Such a network consists of a moderate quantity of low-power, resource-constrained miniature devices (called the sensor nodes) placed in, on or around the body which are usually wirelessly controlled by a portable central control device (called the base station by some researchers). Fig. 1 shows some typical applications in WBSN. In these applications, rather than the peer-to-peer self-organized network topologies, the single-hop star network topology and the master-slave protocol are commonly adopted to lower the system complexity and power consumption as well [1], [4]. A typical WBSN is usually composed of a portable device which serves as the master node for central around, on, or inside the human bodies that act as the slave nodes. Compared to the master node, the slave nodes have more stringent constraints in terms of power consumption and size limitation. And this work mainly focuses on the slave sensor nodes in the WBSNs.control, and a number of miniaturized sensor nodes placed Typical WBSN slave sensor nodes can be used for biomedical information acquisition, signal preprocessing, data storage, and wireless transmission (sometimes direct transmission without any preprocessing). This type of slave sensor node is called the sensing node. In addition, the function of sensor nodes can be expanded to medical treatments, such as drug delivery and nerve stimulating [5], and this type of slave sensor node is called the stimulating node. One difference between the two types of nodes is that the functions of a sensing node are usually periodically performed, while the functions of a stimulating node can be either periodical or event driven. A study has been made on these two types of WBSN nodes, and a network protocol has been proposed and implemented which meets the requirements of both, targeting the power-efficient operations. Specifically, the implemented ASIC has two standby modes. In the active standby mode, only an ultra- lowpower (ULP) timer with a low-frequency clock generator is active, and it periodically power ups the sensor node. In the passive standby mode, the whole sensor node is power silent, and a secondary passive RF receiver works as the supervisor circuit. The specifically designed passive RF receiver can harvest energy from the RF signals in the space (transmitted by the master node which is not power critical), and hence, the passive standby mode consumes zero power ideally. The active standby mode can be used for the sensing and stimulating nodes. As a contrast, the passive standby mode can find its perfect use for the stimulating nodes, since the event-driven stimulating nodes can be woken up on demand without any response latency, while consuming zero power.