A new pipelined-interleaved structure for FIR Hilbert Transformers based on Frequency Transformation technique

Finite Impulse Response (FIR) Hilbert Transformers (HTs) have a high complexity when they are designed with a very sharp transition band and a small ripple. This complexity is dominated by multipliers, the most expensive elements in a digital filter. Frequency Transformation (FT) is a technique to design FIR filters with repeated simple identical subfilters, which can be used to reduce the overall number of distinct multipliers. In this paper an efficient structure based on the Pipelining Interleaving (PI) technique, where only one time-shared subfilter is employed, is proposed for FT-based HTs. The overall number of required multipliers is the same as the number of distinct multipliers used in the FT-based design. It is shown by mean of examples that the HTs designed with the proposed structure require less number of multipliers than previous FT-PI-based existing methods.