Compact wideband CMOS receiver frontends for wireless communication

Abstract Wireless communication is an integral part of our daily life, the mobile phone is an example of a very popular wireless communication device. A communication link consists of a transmitter, a receiver and the transmission medium, which air or vacuum for a wireless link. Part of the receiver is the receiver frontend. The receiver frontend amplifies the weak, high frequency, signal received at the receiver antenna and brings the signal down in frequency. Using further signal processing,including analog-to-digital conversion for modern standards, the message sent by the transmitter can be recovered. There is an increasing demand for wideband receiver frontends. This is due to the emerge of wideband wireless standards (UWB) and due to the desire for flexible radios (SDR), which can comply to multiple existing and future communication standards. Existing receiver topologies are generally narrowband and not suited for wideband operation, consequently there is a need for new wideband receiver topologies. For low cost solutions, compact receiver topologies implemented in mainstream CMOS technology are preferred. In this thesis, wideband receiver operation between a few hundreds of megahertz up to around ten gigahertz, with an input bandwidth of at least a few gigahertz is aimed at. For wideband receivers the required gain, input impedance and noise figure are in the same order as for traditional narrowband receivers. The challenge in wideband receivers is to meet all these specifications across its entire bandwidth. Due to the wideband nature there are many ABSTRACT iv interferer combinations that lead to in-band distortion in wideband receivers, resulting in challenging linearity requirements. At the start of this research project, the noise canceling technique was identified as a suitable candidate to implement wideband receiver frontends. In a preceding research project a number of noise canceling topologies were generated. One of these topologies, the CG-CS topology, is especially useful as it implements two basic receiver frontend functions, low noise amplification and single-ended to differential conversion (balun), into one circuit core. Three designs are implemented during this research project. The CG-autotrafo-CS design, based on the CG-CS topology, yields a lowpower, wideband, low-noise amplifier (LNA) and uses an on-chip transformer. The second designs, the Balun-LNA is also based on the CG-CS topology. This is a wideband LNA design that simultaneously achieves noise canceling, distortion canceling and a well-balanced output signal. The BLIXER topology is a further evolution of the CG-CS topology. Next to balun and LNA-functionality complex frequency down-conversion is realized, all in a single wideband circuit core. During the course of this project, the interest in circuits in wideband LNAs and receiver frontends has increased significantly. Only two circuit techniques found in literature are suitable to implement compact wideband LNAs: negative feedback and noise canceling. From the two LNAs described in this thesis especially the Balun-LNA compares favorably to other designs found in literature. The BLIXER stands out on area and RF-bandwidth when compared with other wideband receiver frontends, while other characteristics are competitive. The BLIXER topology is very suitable for the implementation of compact wideband receiver frontends for wireless communication.