Transmitter And Components Design In Uwb-Rfid System

Ultral-Wideband enabled Radio Frequency Identification (UWB-RFID) is a kind of RFID technology which combines with UWB technology. The information of identification and exchange datas are transmited by UWB signals. UWB-RFID not only retains the original characteristics of RFID such as high efficiency and reliability, but also has new fuctions like precision tag location and chipless tags. Unlike UWB or RFID, There is no standard on UWB-RFID technology now. Hence, there are many ways to realisize UWB-RFID system. For transmitter of the UWB-RFID reader, the structures are also different. The transmitter structures are selected by the specific application and any kind of structures has a great contribution to the development of UWB-RFID.In this papper, a brief introduction to the UWB-RFID transmitter structures is given and a transmitter which includes a gaussian pulse modulation module and a pulse forming network is designed. The gaussian pulse modulation module has two step recovery diodes and can generate195ps pulse width,2.7V amplitude gaussian pulse. The pulse forming network is made of a3GHz to5GHz ultra-wideband bandpass filter. Based on the traditional short-circuited stubs UWB bandpass filter, a new medthod to design a UWB bandpass filters is provided. By intronduce a cross coupling between the input and output short circuited stub, a pair of transmission zeros, which can improve frequency selectivity, are appeared. Two new UWB bandpass filter are designed in this paper to form the gaussian pulse which comes from the guassian pulse modulation module. Finnal, a5order differential guassin pulse with3GHz to5GHz bandwidth is obtained.