A low complexity and high modularity design for continuously variable bandwidth digital filters

Abstract

Digital filters with variable bandwidth can be used for a variety of applications. Arbitrary change in the bandwidth of a digital Finite Impulse Response (FIR) filter can be acquired using sampling rate converters (SRCs). In this paper, a SRC is proposed which is generated from Pascal structure, a fractional delay filter having low hardware complexity and high modularity. A low-pass filter having a single bandwidth sandwiched between two SRCs can contribute multiple bandwidths in such a way that each bandwidth is an arbitrary variation of the original bandwidth. A two-stage frequency response masking (FRM) approach is used for the hardware efficient design of the original low-pass filter. A low complexity and high modularity novel design for a continuously varying bandwidth of a digital FIR filter is proposed in this paper using the proposed SRC. The modularity of the Pascal structure can be used to control both pass band ripple as well as stop band attenuation of the continuously variable bandwidth FIR filter design. Different communication standards in a software-defined radio (SDR) channelizer is realised using the proposed design of continuously variable bandwidth filter.