Patent ID: 7218178

Claim:
A frequency generator, comprising: a phase locked loop with a loop filter, wherein the loop filter is an active filter implemented as a biquad filter and is formed such that a transfer function of the loop filter has a pair of complex conjugated poles, wherein transfer function H PLL (s) of the phase locked loop can be represented as quotient H PLL (s)=P PLL (s)/Q PLL (s) of a numerator polynomial P PLL (s) and a denominator polynomial Q PLL (s)=q N−1,PLL s N−1 +q N−2,PLL s N−2 + . . . +q 0,PLL s 0 , wherein the transfer function Z LF (s) of the loop filter can be represented as quotient Z LF (s)=P LF (s)/Q LF (s) of a numerator polynomial P LF (s)=p 1,LF s+p 0,LF and a denominator polynomial Q LF (s)=q N−1,LF s N−1 +q N−2,LF s N−2 + . . . q 0,LF s 0 =(s−s ∞PLL,1 )·(s−s ∞PLL,2 )· . . . ·(s−s ∞PLL,N ) with the poles s ∞PLL,n , and wherein the filter is formed such that the poles s ∞PLL,n are chosen so that the phase noise of the phase locked loop has a predetermined value and the settling time of the phase locked loop is minimal.