Grant: Collaborative Research and Development Grants

All wireless communications base station transceivers require frequency division duplex (FDD) duplexers to isolate the transmitting band of frequencies from the receiving band. Conventional FDD duplexers consist of multiple high-order bandpass filters, each having multiple high quality poles. These filters are relatively bulky, and are not electrically reconfigurable. The vendors of Base Station Transceivers (BTS) must offer duplexers that operate in the bands that their customers are using. This results in a requirement for a large number of individual duplexer designs. If a duplexer were reconfigurable, then one device could satisfy the specifications of multiple customers. In addition, wireless network operators must adopt a specific wireless Standard and frequency band before building their network since parts of the radios, including the duplexer, are application specific. Investing in equipment that works for a single wireless standard, in a specific frequency band has inherent risks. These risks would be reduced if the radio equipment were reconfigurable for different Standards and frequencies. The proposed research presents a fundamental change to duplexer design. Requirements for high-order, high-dynamic range, low-loss, low-distortion and low-noise filtering exclude the use of a hybrid Radio Frequency-Digital Signal Processing (RF-DSP) solution in the RF front-end. Instead, we propose the use of a feed-forward configuration, with DSP in one path, and employing negative group delay to compensate for the relatively large latency inherent to the DSP.