7. (15 points) Consider the down-conversion process from carrier frequency $f_c$ to complex
baseband signal $s(t) = x(t) + iy(t)$, such that the carrier frequency is much larger than
the baseband bandwidth, $f_c \gg B$.
(a) By considering received signal, ADC, mixer, phase shifters, filters, and amplifier blocks,
draw the block diagram of a direct down-converter.