Question

A real 40MHz sinewave is sampled at 100M Hz. (a) List all frequencies up to 200MHz that would alias into 40MHz. (b) Specify the appropriate cutoff frequency for the filter that should be employed by the 100MHz A/D converter. (This is not dependent in this particular input; I mean if you built a 100MHz A/D converter, what should the cutoff frequency be for this filter). (c) Specify the input signal frequency on the following scales (with units): analog radian frequency, normalized digital radian frequency, as a fraction of the sampling rate, and as a fraction of the Nyquist bandwidth.

Answer 1

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(b) Geven ds = 100 tulity to nyanist aitwia to eliminate atasaug By ry amist aitria 12.27 Vmax Imax= tsp = 50 MHz Cutoff frequency - fn-50 MHg 10 Given f= 40m Heg - In andersom frequency I w: 20 = 80M Ti rad Hz - In digital madian frequency at for an 1 277 40 271 = 0.8T As a fraction of sampling 100 Fs frequency 404 a 0.4 THOM Is nist band suidth. y AA a 50 MHz tms. As a fraction of nyquist band suidth. Ny amerte Bend tuidi e ifm, 50 m tay. . Bond nidth =