ZPLANE(Z,P) plots the zeros Z and poles P (in column vectors) with the
    unit circle for reference.

S平面 Z P 点plot：
PZMAP  Pole-zero map of LTI models.

pzmap, zp2tf, tf2zp, roots 求零极点图

  See also pole, zero, sgrid, zgrid, rlocus, ltimodels.

pi=3.1415926;
% P=bodeoptions;
% P.Grid='on';
% P.XLim={[10      40000]};
% P.XLimMode={'manual'};
% P.FreqUnits='HZ';

%input stage:
gm = 1e-3;
s = tf('s');
%MOS cascode
r2 = 20e3; %
gm2=5e-4;

%boost device
Au = 10^(40/20) ; %boost = 40dB
GBu = 100e6*2*pi; %boost GB bandwidth, f*2*pi
H_boost = Au/(1+Au/GBu*s); %one pole only

%current source
r1 = 20e3; %
c1 = 50e-15; %parasitic cap
% c1 = 0;
Z1 = -1*r1/(1+s*r1*c1);

%rout:
rout = r1+Z1-Z1*(H_boost - 1)*gm2;
zpk_rout = zpk(rout);
%figure(1); bode(rout,[6.28 6.28e10]) ;grid on;

%impedance out:
% GBORG = 500e6; AORG=10^(40/20);
%cload = 1/((r1+r2+gm2*r1*r2*Au)*GBORG*2*pi)
cload = 5e-12 ;

zout = rout/(1+rout*cload*s);
tf_total = 1*zout;

%plot:
zpk_out = zpk(tf_total);
figure(1); bode(tf_total,[6.28 6.28e10]) ;grid on;

% figure(3);pzmap(tf_total);grid on; 
Ptotal = pole(tf_total);Ptotal_choose= [];
j=1;
for i = 1:length(Ptotal)
        if abs(Ptotal(i))< 1e9 
        Ptotal_choose(j) = Ptotal(i);
        j=j+1;
        end
end

Ztotal = zero(tf_total);Ztotal_choose=[];
j=1;
for i = 1:length(Ztotal)
        if abs(Ztotal(i))< 1e9
        Ztotal_choose(j) = Ztotal(i);
        j=j+1;
        end
end
 Ptotal_choose = Ptotal_choose / 6.28
 Ztotal_choose = Ztotal_choose / 6.28
 figure(2);pzmap(Ztotal_choose,Ptotal_choose);
--by ycc 版权所有