International Journal of Electrical Electronics & Computer Science Engineering Volume 2, Issue 1 (February, 2015), ISSN : 2348-2273 Available Online at www.ijeecse.com 8 Highly Efficient Power Amplifier Co-Design with Circular Microstrip Antenna Deeksha Bajpai 1 , Amit Chaudhary 2 , Sandeep Kumar 3 1 M.Tech Scholar, IMS Engineering College, Ghaziabad, India 2 Assistant. Professor, IMS Engineering College, Ghaziabad, India 3 Assistant. Professor, GIMS Engineering College, Greater Noida, India deeksharkgit@gmail.com Abstract: This paper categories in three module in first module schematic and parameter of power amplifier is defined and in second module design the circular patch antenna and in third module the circular patch antenna co-design with power amplifier. The micro-strip antenna is a small electrically thin patch having numerous of advantages i.e. light weight, inexpensive, and easily integration with active devices for improving system reliability. One of the major goals of this work is to overcome the challenges faced by CMOS technology in the design of a higher output power, high-efficiency, fully integrated, and good linearity. To achieve best efficiency and high output power, this work designed the CMOS Power and the power amplifier at 31GHz frequency. This Work will make possible through the guidance in using the ADS tool facility (0.09 μm Technology) for simulations. The performance parameters of the amplifiers which have been estimated are trade off with others that should overcomes a multidimensional optimization problem of the designers Precisely, this work in hand takes up the objective “It is necessary to examine closely the design process of analogy circuits and to identify those principles that will increase design productivity & the designer’s chances for success”. I. INTRODUCTION The rapid progress in personal wireless communication devices has made the development of the electrically small antennas (ESAs) the centre of many research interests. A large variety of miniature antennas, such as printed dipoles, dielectric resonance antennas, micro strip patch antennas, inverted L antennas, inverted F antennas, planar inverted F antennas, etc. has been developed with the emergence of mobile handheld devices. The success of these devices largely relies on the progress and innovation in dielectric materials, the optimization of size, gain, bandwidth, or matching for miniature antennas. In addition to the many common requirements in ESAs for conventional handheld devices, such as low cost, light weight, compact, gain and bandwidth performance, antennas in ultra wireless wideband communication technology. Therefore, the brief detail of circular patch compact antenna and new co-design technique (Antenna with PA) has been explained the following subsection. The main idea consists to design "simultaneously" PA and antenna in order to optimize the whole system. This implies first to interface both distinct designers communities and their tools. Practically a joint simulation platform (ADSR) makes the interface between calculated impedances from EM simulator (Ansoft HFSS) for the antenna and from circuit design tool (ADSR) for the PA. Then, for both components, several key parameters have been judiciously selected for their ability to modify and control the complex impedance profile versus frequency. A set of parametric co-simulations is processed. The available degrees of freedom are used to optimise different performances of the whole system "Antenna- PA" such as the transducer gain, the noise figure. This platform is mainly used as a circuit-based interface between antenna circuit model and PA circuit model. It is useful to take into account the wire bonding inductive effect. II. CIRCULAR SHAPED MICROSTRIP ANTENNA (CMSA) The micro-strip antenna is a small electrically antenna that has a number of advantages over the other antennas i.e. lightweight, inexpensive, and easy to integrate with active devices to improve the system reliability. In this, we have design a rectangular patch antenna that is resonant at 31 GHz with new type of micro-strip feeding and simulated in ADS tool. All the design work taken a RT durroid substrate with thickness of t = 0.2431 mm at the height h = 10mil above a lossless ground conducting layer. The dielectric between metal layers is assumed to have ∈  = 2.36 and tan = .002. At 31 GHz, a 310Ω feed line given these parameters would have a width and length is 2mm and 0.7mm respectively and the final dimensions of the patch are a length L = 2.2mm and a width W = 2.4mm respectively. Figure.1 Geometry of circular Patch antenna