Page 201 - DSP Integrated Circuits

186 Chapter 4 Digital Filters

4.30 Determine the required filter order and the work load if the interpolation
(case study) is done in a single step using a lattice wave digital filter.
4.31 Determine the required filter order and the work load for the interpolation
(case study). Assume that the interpolation is done in
(a) A single step using an FIR filter
(b) Two steps using FIR filters

4.32 Determine the specification of the combined interpolating and decimating
filter required when the sampling frequency is changed by a factor L/M. The
input signal is bandlimited to the band 0 to co^T < n.
4.33 Determine the specification for the digital filter required in a sample rate
converter that will increase the sampling rate by a factor 2.5. The ripple in
the passband should be less than 0.5 dB and the attenuation should be
larger than 40 dB. The bandwidth of the input signal is 200 kHz and the
sampling frequency is 1.2 MHz.
4.34 (a) Develop a multistage scheme for a sampling rate converter between DAT
(48 kHz) and CD (44.1 kHz). An FIR filter is used as a lowpass filter,
(b) Determine the reduction in work load due to multiplication by zero
values.
4.35 Write a MATLAB program that can be used to design lowpass lattice
WDFstll].

DESIGN PROJECTS

1. Develop a specification and a functional description that can be used to
design an interpolator for a CD player. Assume that the chip is to be used in
a battery-powered application that is expected to be produced in large
volumes. Compare your result with some commercial chips.
(a) Use an FIR filter approach.
(b) Use a lattice wave digital filter approach.

2. Redesign the interpolator using a ninth-order filter for the last stage and use
the computational resources that are saved to increase the order of the
allpass filter.
3. Develop a specification and a functional description that can be used to
design a simple filter bank for equalization in a CD player. Assume that the
chip is going to be used in a battery-powered application that is expected to
be produced in large volumes. Compare your result with some commercial
chips.
(a) Use a tree of complementary FIR filters.
(b) Use a tree of bireciprocal lattice wave digital filters.