A programmable multistage half-band FIR decimator for input data rates up to 2.56 MSPS

A multistage half-band FIR (finite impulse response) decimator has been implemented on a 40000-gate, 1.5-μm CMOS gate array, which dissipates 1.5 W at a clock rate of 25.6 MHz (a sampling rate of 2.56 MHz). The filter handles 20-b, 2.56-M sample/s input data. It has been tested for frequency shifting and zooming in a prototype FFT (fast Fourier transform) spectrum analyzer and has increased the frequency resolution by up to 2¹⁷ times without aliasing, resulting in frequency resolution on the order of 20 mHz; it has a 96-dB dynamic range