Lattice Semiconductor announces its Rake Receiver reference design, targeted at basestations in wireless telecom applications. A Rake Receiver is used to counter the effects of RF multipath fading due to atmospheric absorption, ionospheric reflection and refraction, and reflection from terrestrial objects such as mountains and buildings. The technique uses several sub-receivers, each delayed slightly, in order to tune in the individual multipath components and then combine them to optimize the signal reception. The reference design uses the LatticeECP (EConomy Plus) FPGAs that combine an FPGA fabric with high-speed, dedicated DSP blocks on-chip. The reference design has the following features (one instance of the rake engine): 61.44 MHz operating frequency; interpolation of two times over-sampled input data to 1/16 of a chip resolution; handling of 16 control channels and 16 data fingers; simultaneous generation of 16 scrambling codes at chip rate; simultaneous generation of 16 Orthogonal Variable Spreading Factor (OVSF) codes; and de-scrambling and dispreading of input signals with 16 different delays.
Lattice Semiconductor Corporation