function [Out1,Out2]=qsynth(Action,In1,In2)
% Dick Benson
% Design single terminated elliptic passive LC low pass filters.
% Copywrite 2001-2010 The MathWorks, Inc.
% [L,C] = qsynth('getLC');
if nargin ==0
Action = 'init';
end;
if ~strcmp(Action,'init')
Hqsynth_ = get(gcf,'userdata');
end
% handle index definitions
i_f1 = 1;
i_topology = 2;
i_order = 3;
i_synthpb = 4;
i_ripl = 5;
i_ripv = 6;
i_stopl = 7;
i_stopv = 8;
i_ax1 = 9;
i_pl1 = 10;
i_pl2 = 11;
i_fcl = 12;
i_fcv = 13;
i_lv = 14;
i_cv = 15;
i_lcl = 16;
i_testpb = 17;
if strcmp(Action,'init')
Hqsynth_(i_f1)= figure('Color',[0 0 0] ,'Name','Qsynth: Single Terminated Ladder Elliptic Filter',...
'Position',[20 20 640 440],...
'Resize','off',...
'Color',[0 0 1],...
'NumberTitle','off','visible','on');
% ###### userdata contains vector of handles if desired
Hqsynth_(i_topology)=uicontrol('Style','popup','visible','on',...
'String','RIN=1,RL=inf|RIN=0,RL=1',...
'Position',[10 400 105 20],...
'BackgroundColor',[0 0 0],...
'ForeGroundColor',[0 1 1],...
'Value',1,...
'callback','qsynth(''clear'')',...
'HorizontalAlignment','Left');
Hqsynth_(i_order)=uicontrol('Style','popup','visible','on',...
'String','Order:3|Order:5|Order:7|Order:9|Order:11',...
'Position',[10 380 105 20],...
'BackgroundColor',[0 0 0],...
'ForeGroundColor',[0 1 1],...
'Value',4,...
'HorizontalAlignment','Left');
Hqsynth_(i_ripl) = uicontrol('Style','text','visible','on',...
'String','Ripple (dB):',...
'Position',[10,355,60,18],...
'BackGroundColor',[1 1 1]*0.8,...
'ForeGroundColor',[0 0 0],...
'HorizontalAlignment','left');
Hqsynth_(i_ripv) = uicontrol('Style','edit','visible','on',...
'Position',[70,355,45,18],...
'String','1',...
'BackgroundColor',[1 1 0],...
'ForeGroundColor',[0 0 0],...
'HorizontalAlignment','center',...
'Max',1);
Hqsynth_(i_stopl) = uicontrol('Style','text','visible','on',...
'String','Stop (dB):',...
'Position',[10,330,60,18],...
'BackGroundColor',[1 1 1]*0.8,...
'ForeGroundColor',[0 0 0],...
'HorizontalAlignment','left');
Hqsynth_(i_stopv) = uicontrol('Style','edit','visible','on',...
'Position',[70,330,45,18],...
'String','60',...
'BackgroundColor',[1 1 0],...
'ForeGroundColor',[0 0 0],...
'HorizontalAlignment','center',...
'Max',1);
Hqsynth_(i_fcl) = uicontrol('Style','text','visible','on',...
'String','Cutoff (Hz):',...
'Position',[10,305,60,18],...
'BackGroundColor',[1 1 1]*0.8,...
'ForeGroundColor',[0 0 0],...
'HorizontalAlignment','left');
Hqsynth_(i_fcv) = uicontrol('Style','edit','visible','on',...
'Position',[70,305,45,18],...
'String','1.0e6',...
'BackgroundColor',[1 1 0],...
'ForeGroundColor',[0 0 0],...
'HorizontalAlignment','center',...
'Max',1);
Hqsynth_(i_lcl) = uicontrol('Style','text','visible','on',...
'String',' L C',...
'Position',[10,280,165,18],...
'BackGroundColor',[1 1 1]*0.8,...
'ForeGroundColor',[0 0 0],...
'HorizontalAlignment','left');
Hqsynth_(i_lv) = uicontrol('Style','edit','visible','on',...
'Position',[10,35,85,240],... % was 80
'String','',...
'BackgroundColor',[1 1 0],...
'ForeGroundColor',[0 0 0],...
'HorizontalAlignment','left',...
'Max',14);
Hqsynth_(i_cv) = uicontrol('Style','edit','visible','on',...
'Position',[100,35,85,240],... % was 95,35,80
'String','',...
'BackgroundColor',[1 1 0],...
'ForeGroundColor',[0 0 0],...
'HorizontalAlignment','left',...
'Max',14);
Hqsynth_(i_ax1)=axes('Units','pixels','Position',[240,80,370,300],...
'Box','on',...
'visible','on',...
'NextPlot','add',...
'DrawMode','fast',...
'Color',[0 0 0],...
'TickDir','out',...
'YlimMode','auto',...
'XlimMode','auto',...
'Xcolor',[1 1 1],...
'Ycolor',[1 1 1],...
'FontSize',12);
title('Singly Terminated Elliptic Filter ','color',[1 1 1],'fontsize',9);
xlabel('Frequency in Hz','fontsize',9);
ylabel('Magnitude in dB','fontsize',9)
Hqsynth_(i_pl1) = plot(Hqsynth_(i_ax1),0,0,'clipping','on',...
'Color',[0 1 0],...
'erasemode','xor','visible','on');
Hqsynth_(i_pl2) = plot(Hqsynth_(i_ax1),0,0,'clipping','on',...
'Color',[1 0 0],...
'erasemode','xor','visible','on');
Hqsynth_(i_synthpb) = uicontrol('Style','Pushbutton',...
'Position',[10,10,105,20],...
'String','Synthesize',...
'Callback','qsynth(''synth'');');
Hqsynth_(i_testpb) = uicontrol('Style','Pushbutton',...
'Position',[120,10,105,20],...
'String','Test',...
'Callback','qsynth(''test'');');
set(Hqsynth_(i_f1),'userdata',Hqsynth_);
zoom on
elseif strcmp(Action,'synth')
fmtstr = '%8.5g';
n = get(Hqsynth_(i_order),'value')*2+1; % only odd orders supported
rp = str2num(get(Hqsynth_(i_ripv),'string'));
rs = str2num(get(Hqsynth_(i_stopv),'string'));
wn = 2*pi*str2num(get(Hqsynth_(i_fcv),'string'));
[b,a]=ellip(n,rp,rs,wn,'s');
save lpf_coefs b a
w = 0:(wn/25):10*wn;
h = freqs(b,a,w);
set(Hqsynth_(i_ax1),'Ylim',[-rs-20,5],'Xlim',[0,10*wn/(2*pi)]);
set(Hqsynth_(i_pl1),'xdata',w/(2*pi),'ydata',20*log10(h));
topology = get(Hqsynth_(i_topology),'value');
if topology ==1
% Rin = 1, Rl = inf , Vsource with 1 ohm Z0, no load
% must be odd order
m = b(2:length(b));
zeros = roots(m);
m2 = [];
n2 = [];
for i=1:length(a)
if rem(i,2)
n2=[n2,a(i),0];
else
m2=[m2,a(i),0];
end;
end;
m2=m2(1:(length(m2)-1));
% remove admittance pole @ s=inf
% z=m2/n2 y = n2/m2 yp = n2/m2-c1s
C(1) = n2(1)/m2(1); % shunt capacitor
n2 = n2 - conv(m2,[C(1),0]);
% now it gets tricky ....
for i = 1:(n-1)/2
% need an xmission zero @ w=wx
wx = j*abs(zeros(2*i)); % pick an xmission zero....
% do a partial removal of the impedance pole @ inf
% first evaluate impedance @ w=wx
zmag = polyval(m2,wx)/polyval(n2,wx);
L(2*i) = zmag/wx;
if i==1
n2=n2(3:length(n2));
end;
% this partially removes the pole
m2 = m2-conv(n2,[L(2*i),0]);
% now remaining admittance has a pole at w=wx
% remove it by shunting a series LC
% first must determine L & C values
[q,r1]= deconv(m2,[1 0 abs(wx)^2]); % r should be zero
k = n2(1);
n2p = n2/k;
n2p = n2p(1:length(n2p)-1);
L(2*i+1)=1/(k*(polyval(n2p,wx)/polyval(q,wx)));
C(2*i+1)= 1/(L(2*i+1)*(abs(wx)^2));
% then remove the addmittance.... not obvious!
[n2pp,r2] = deconv(( n2p-q/(k*L(2*i+1)) )*k,[1 0 1/(C(2*i+1)*L(2*i+1))]);
n2 = conv(n2pp,[1 0]);
m2 = q;
end;
L=L';
C=C';
elseif topology==2
% Rin=0, Rl=1 (Vsource input, 1 ohm load)
%
m = b(2:length(b)); % drop leading 0.0 term
zeros = roots(m); %
m2 = [];
n2 = [];
for i=1:length(a)
if rem(i,2)
n2=[n2,a(i),0];
else
m2=[m2,a(i),0];
end;
end;
m2=m2(1:(length(m2)-1));
for i = 1:(n-1)/2
% need an xmission zero @ w=wx
wx = j*abs(zeros(2*i)); % pick an xmission zero....
% do a partial removal of the impedance pole @ inf
% first evaluate impedance @ w=wx
zmag = polyval(n2,wx)/polyval(m2,wx);
L(2*i-1) = zmag/wx;
% this partially removes the pole
n2 = n2-conv(m2,[L(2*i-1),0]);
% now remaining admittance has a pole at w=wx
% remove it by shunting a series LC
% first must determine L & C values
[q,r1] = deconv(n2,[1 0 abs(wx)^2]); % r should be zero
k = polyval(m2,wx)/polyval(conv(q,[1 0]),wx);
L(2*i) = 1/k;
C(2*i) = 1/(L(2*i)*(abs(wx)^2));
[p,r2] = deconv( m2-k*conv(q,[1 0]) , [1 0 abs(wx)^2]);
m2=p;
n2=q;
end;
L(n)= n2(1)/m2; % final series L .... amazing .... absolutly amazing!
L = fliplr(L)'; % need to reverse this network
C = [0,fliplr(C)]'; %
end;
set(Hqsynth_(i_ripl),'userdata',L);
set(Hqsynth_(i_ripv),'userdata',C);
s='';
for i=1:(length(L)-1)
s=[s,sprintf([fmtstr,'\n'],L(i))];
end;
s=[s,sprintf(fmtstr,L(length(L)))];
set(Hqsynth_(i_lv),'string',s);
s='';
for i=1:(length(C)-1)
s=[s,sprintf([fmtstr,'\n'],C(i))];
end;
s=[s,sprintf(fmtstr,C(length(C)))];
set(Hqsynth_(i_cv),'string',s);
elseif strcmp(Action,'getLC');
% Out1 = get(Hqsynth_(i_ripl),'userdata'); % inductors
% Out2 = get(Hqsynth_(i_ripv),'userdata'); % capacitors
% huh? , should get it from strings in edit fields
caps = get(Hqsynth_(i_cv),'string');
inds = get(Hqsynth_(i_lv),'string');
for i=1:length(caps(:,1))
Out2(i) = str2num(caps(i,:));
end;
for i=1:length(inds(:,1))
Out1(i) = str2num(inds(i,:));
end;
elseif strcmp(Action,'test')
topology = get(Hqsynth_(i_topology),'value'); % network topology
wn = 2*pi*str2num(get(Hqsynth_(i_fcv),'string'));
w = 0:(wn/25):10*wn;
[L,C]=qsynth('getLC');
if topology ==1
% test the synthesis
% begin with source resistor
[a,b,c,d,q]=pabcd([],[],[],[],[],'rs',1);
% then the shunt capacitor
[a,b,c,d,q]=pabcd(a,b,c,d,q,'cp',C(1));
for i = 1:(length(L)-1)/2
% series L
[a,b,c,d,q]=pabcd(a,b,c,d,q,'ls',L((i*2)));
% shunt series LC
[a,b,c,d,q]=pabcd(a,b,c,d,q,'lcs',L((i*2)+1),C((i*2)+1));
end;
elseif topology ==2
a = []; b = []; c = []; d = []; q = [];
for i = 1:(length(L)-1)/2
% series L
[a,b,c,d,q]=pabcd(a,b,c,d,q,'ls',L((i*2-1)));
% shunt series LC
[a,b,c,d,q]=pabcd(a,b,c,d,q,'lcs',L((i*2)),C((i*2)));
end;
% finish with a series L
[a,b,c,d,q]=pabcd(a,b,c,d,q,'ls',L(length(L)));
% and a 1 ohm shunt R load resistor
[a,b,c,d,q]=pabcd(a,b,c,d,q,'rp',1);
end;
% [mag,phase] = bode(q,a,w);
h = freqs(q,a,w);
set(Hqsynth_(i_pl2),'xdata',w/(2*pi),'ydata',20*log10(h));
elseif strcmp(Action,'clear')
set(Hqsynth_(i_ripl),'userdata',[]);
set(Hqsynth_(i_ripv),'userdata',[]);
set(Hqsynth_(i_cv),'string','');
set(Hqsynth_(i_lv),'string','');
set(Hqsynth_(i_pl2),'xdata',[],'ydata',[]);
set(Hqsynth_(i_pl1),'xdata',[],'ydata',[]);
else
disp([Action,' not reconized in qsynth'])
end;
% end qsynth
function [aout,bout,cout,dout,qout]=pabcd(ain,bin,cin,din,qin,element,val1,val2,val3)
% [aout,bout,cout,dout,qout]=pabcd(ain,bin,cin,din,qin,element,val1,val2)
% Uses chain matrix parameters to cascades abcd with denominator q (in)
% with an element that has val1 (val2 for LC).
% Useful for computing functions & parameters of ladder networks.
% element code description
% rs = series resistor
% lcs = shunt series lc val1=l val2=c
% ls = series l
% cp = shunt c
% rp = shunt r
% lcp = series chunt lc val1=l val2=c val3 = r (in series with l for loss)
%
% a*e2-b*i2 = e1
% c*e2-d*i2 = i1
%
% Dick Benson
%
if strcmp(element,'rs')
% rs = series resistor
a = 1;
b = val1;
c = 0;
d = 1;
q = 1;
elseif strcmp(element,'lcs')
% lcs = shunt series lc
% l=val1 c=val2
q = [val1*val2, 0 , 1];
a = q;
b = 0;
c = [val2 0];
d = q;
elseif strcmp(element,'lcp')
% l=val1 c=val2
q = [val1*val2 val2*val3 1];
a = q;
b = [val1 val3];
c = 0;
d = q;
elseif strcmp(element,'ls')
% ls = series l
a = 1;
b = [val1 0];
c = 0;
d = 1;
q = 1;
elseif strcmp(element,'cp')
% cp = shunt c
q = 1;
a = 1;
b = 0;
c = [val1 0];
d = 1;
elseif strcmp(element,'rp')
% rp = shunt r
q = 1;
a = 1;
b = 0;
c = 1/val1;
d = 1;
else
disp([element,' not supported in pabcd '])
end;
if isempty(ain)
aout=a;
bout=b;
cout=c;
dout=d;
qout=q;
else
aout = padd(conv(ain,a),conv(bin,c));
bout = padd(conv(ain,b),conv(bin,d));
cout = padd(conv(cin,a),conv(din,c));
dout = padd(conv(cin,b),conv(din,d));
qout = conv(qin,q);
end;
% end function
function pout = padd(p1,p2)
lp1 = length(p1);
lp2 = length(p2);
if lp1==lp2
pout = p1+p2;
elseif lp2>lp1
pout = p2;
pout((lp2-lp1+1):lp2)=pout((lp2-lp1+1):lp2)+p1;
else
pout = p1;
pout((lp1-lp2+1):lp1)=pout((lp1-lp2+1):lp1)+p2;
end;
% end padd
