VLSI technology is being adopted widely nowadays for biomedical applications to improve healthcare diagnosis, monitoring and cure. Analog devices such as A/D converters for biomedical applications can be of modest precision but need to be very energy efficient in order to operate for decades. CNTFET can be the future alternative to be used in various high performance, low power devices. In this paper we have presented a low power CNTFET based two stage Op-Amp for biomedical A/D converters. A sample and hold circuit is also implemented using CNTFET based Op-Amp to be used in biomedical ADCs. Simulation results of CNTET based circuits are compared with MOSFET circuits. Results indicate improvement of power consumption up to 80%. The proposed circuit simulations are carried out in HSPICE. It is concluded that CNTFET based circuits can be prime choice for low power applications.