I tried to model a simple voltage divider and expect to get 0.5 V output. But I only get around 0.0377 V. Can anyone help me out? I do not sure what is the problem here.
Simple voltage divider using rftoolbox
조회 수: 17(최근 30일)
표시 이전 댓글
goay chan hong
2016년 11월 1일
답변: goay chan hong
2016년 11월 8일
cas_circuit = rfckt.cascade('Ckts',{rfckt.seriesrlc('R',1), rfckt.shuntrlc('R',1)});
freq = [0:0.01e9:10e9];
analyze(cas_circuit, freq)
cas_circuit.AnalyzedResult
sp = sparameters(cas_circuit.AnalyzedResult)
rfplot(sp,'abs')
z0 = cas_circuit.AnalyzedResult.Z0; zS = cas_circuit.AnalyzedResult.ZS; zL = cas_circuit.AnalyzedResult.ZL;
z0 = real(z0); zS = real(zS); zL = real(zL);
%----------------------------------------------------------------------------------------
%at this point we already constructed the circuit, we will need to generate
%the input
difftf = s2tf(sp);
[rationalfunc, errdb] = rationalfit(freq,difftf)
npoles = length(rationalfunc.A);
fprintf('The derived rational function contains %d poles.\n',npoles);
%------------------------------------------------------------------------
freqsforresp = linspace(0,10e9,1001)';
resp = freqresp(rationalfunc,freqsforresp);
figure
subplot(2,1,1)
plot(freq*1.e-9,(abs(difftf)),'r',freqsforresp*1.e-9, ...
(abs(resp)),'b--','LineWidth',2)
title(sprintf('Rational Fitting with %d poles',npoles),'FontSize',12)
ylabel('Magnitude (decibels)')
xlabel('Frequency (GHz)')
legend('Original data','Fitting result')
subplot(2,1,2)
origangle = unwrap(angle(difftf))*180/pi+360*freq'*rationalfunc.Delay;
plotangle = unwrap(angle(resp))*180/pi+360*freqsforresp*rationalfunc.Delay;
plot(freq*1.e-9,origangle,'r',freqsforresp*1.e-9,plotangle,'b--', ...
'LineWidth',2)
ylabel('Detrended phase (deg.)')
xlabel('Frequency (GHz)')
legend('Original data','Fitting result')
%--------------------------------------------------------------------------
ak = [0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,1];
Dk = [1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1];
numofSR = length(Dk);
out = [];
for k = 1:1000
out = [out,Dk(numofSR)];
newbit = mod(sum(ak.*Dk),2);
Dk(numofSR) = []; Dk = [newbit, Dk];
end
datarate = 1*1e9; % Data rate: 1 Gbps
samplespersymb = 100;
pulsewidth = 1/datarate;
ts = pulsewidth/samplespersymb;
numsamples = 5000;
numplotpoints = 100000;
t_in = double((1:numsamples)')*ts;
%out?
input_signal = out;
input_signal = repmat(input_signal,[samplespersymb, 1]);
input_signal = input_signal(:);
[output_signal,t_out] = timeresp(rationalfunc,input_signal,ts);
if ~isempty(which('commscope.eyediagram'))
if exist('eyedi','var')
close(eyedi)
end
eyedi = commscope.eyediagram('SamplingFrequency',1./ts, ...
'SamplesPerSymbol',samplespersymb,'OperationMode','Real Signal');
% Update the eye diagram object with the transmitted signal
estdelay = floor(rationalfunc.Delay/ts);
update(eyedi,output_signal(estdelay+1:end));
end
max(output_signal)
overSampleRate = round((1/ts)/datarate
채택된 답변
MathWorks RF & Mixed-Signal Products Team
2016년 11월 7일
Hi Goay Chan Hong,
I think you did not take into account the source and load impedance when computing the transfer function from the S-parameters. Moreover I would build the voltage divider network using the "circuit" syntax, as I find it more intuitive.
I would change part of your code to look like the following. Notice that I used option "2" to compute the transfer function.
Hope this helps, with best regards, Giorgia
ckt = circuit('VoltageDivider');
R = 1;
add(ckt,[1 2], resistor(R))
add(ckt,[2 0], resistor(R))
freq = (0:0.01e9:10e9);
setports(ckt,[1 0],[2 0])
S = sparameters(ckt,freq);
rfplot(S,'abs')
difftf = s2tf(S,1e-12,1e12,2);
[rationalfunc, errdb] = rationalfit(freq,difftf);
freqsforresp = linspace(0,10e9,1001)';
resp = freqresp(rationalfunc,freqsforresp);
figure
plot(freq*1.e-9,((difftf)),'r',freqsforresp*1.e-9, ...
((resp)),'b--','LineWidth',2)
ylabel('Magnitude (linear)')
xlabel('Frequency (GHz)')
legend('Original data','Fitting result')
댓글 수: 0
추가 답변(1개)
참고 항목
범주
Find more on Serial Link Design in Help Center and File Exchange
제품
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!