APPARATUS AND METHOD FOR PHASE LOCKED LOOP BANDWIDTH EXPANSION

摘要

An apparatus for PLL bandwidth expansion including a compensation filter and a phase locked loop, where the compensation filter is programmed with a compensation function derived based on programmable coefficients and parameters of a transmitting device, a frequency response of the phase locked loop, and a wanted frequency response.

主权项

1. An apparatus for phase locked loop (“PLL”) bandwidth expansion comprising:
a transmitting device including a compensation filter and a PLL installed in front of the compensation filter, the compensation filter configured to be programmed with a compensation function having filter coefficients, wherein the filter coefficients are set from programmable coefficients and parameters of a transmitting device, and wherein a function of the compensation filter (“Fcomp(s)”) is:Fcomp(s)=y0·(s5+s4·x4+s3·x3+s2·x2+s·x1+x0)x1·(s5+s4·z4+s3·z3+s2·z2+s·z1+z0),wherex0=a·KφA·b·wn2·KvcoNx0=KφA·b·wn2·KvcoNx2=wn2·b,x3=wn2+2ξ·wn·bx4=wn2+2ξ·wn·by0=wa4y1=b1·wa3y2=b2·wa2y3=b3·waz0=y0·x0x1z1=y0+y1·x0x1z2=y1+y2·x0x1z3=y2+y3·x0x1z4=y3+x0x1 and where s is a Laplace transform operator (jw), x0, x1, x2, x3, x4, y0, y1, Y2, y3, z0, z1, Z2, z3, and z4, are the filter coefficients, and Kφ, Kvco, A, N, a, b, wn, wa, and ξ are the programmable coefficients and parameters such that Kφ includes phase detector gain, Kvco includes voltage controlled oscillator gain, A includes a gain value, N includes a variable divider value, a includes a ‘zero’, b includes a ‘pole’, wn includes a filter natural frequency, wa is a desired bandwidth, and ξ includes a damping factor, and wherein a frequency response of the PLL combined with the compensation filter (“Freq(s)”) is:Freq(s)=wa4s4+s3·b3·wa+s2·b2·wa2+s·b1·wa3+wa4.