I am looking at Figure 13.119 in The Art of Electronics, which shows a psuedo random bit sequence generator using shift registers. I understand how this functions. It then takes taps off of the shift registers, using various resistor values to feed into an op amp circuit which then outputs the noise... The book mentions that the values are derived from sin(x) / x [I think?].

What I am asking is, how and why the resistor values used were chosen? And why this works with the op amp configuration shown?

Here is the figure for reference:

[![figure 13.119](https://i.stack.imgur.com/oOGoo.png)](https://i.stack.imgur.com/oOGoo.png)