A sequential multiplexer is connected as shown in figure. Each time the multiplexer receives the clock, it switches to the next channel (From $6$ it goes to $1$). If the input signals are
$A=5 \cos 2 \pi\left(4 \times 10^3 t\right)$
$B=2 \cos 2 \pi\left(3.8 \times 10^3 t\right)$
$C=6 \cos 2 \pi\left(2.2 \times 10^3 t\right)$
$D=4 \cos 2 \pi\left(1.7 \times 10^3 t\right)$
he minimum clock frequency should be _________ $\mathrm{KHz}$.
