Ultra Fast Frequency Hopping Transceiver Design and Implementation for Secure Wireless Communication

Abstract

Frequency hopping spread spectrum (FHSS) is used in a completely new way to pro- vide processing gain for the rst time.To improve the in-band blocker handling capability of the receiver the processing gain is realized in RF domain. The RF transceiver system is designed to provide 20dB of processing gain before any amplication occurs in receiver chain. This enables the receiver to reduce any in-band blocker by 20dB before the LNA and provide self-interference cancelation for the local transmitter that is located on the same chip. This enhances the dynamic range of the receiver above what has been possi- ble before. Since this is the rst attempt to build such a system, no system level analysis existed prior to this work. So on top of IC design, system level design and modeling of the system is presented as well. Two major circuits were developed before this system was feasible. First, an ultra- fast front-end band-pass lter was designed to perform the correlation function. This circuit needs to switch frequency in extremely short periods of time, i.e. 20ns. Secondly, since the correlator circuit hopping speed depends on a fast-hopping LO signal, a signal generator sub-system was developed to generate the LO o a constant frequency RF signal. This sub-system consists of a digital oscilator, DAC, and an injection locked oscillator (ILO) that is used as a high-Q band-pass lter that can in theory switch frequency instantaneously. The digital nature of the LO generation circuits and the ILO's ability to move fast in frequency domain enables the sub-system to generate ultra- fast hopping LO signals. The system is designed to accommodate 470Kbps in various wireless channel environ- ments while providing 20dB of processing gain. This translates into 50 Mhop/s frequency hopping speed that is more than 300 times faster than the state of the art. The RF met- rics of developed components and system level performance are proven in silicon and measurements are reported. The results are presented here and in top conferences and journal papers.