Saturday, November 2, 2013

Wednesday, October 23, 2013

Saturday, October 19, 2013

Sunday, October 6, 2013

Tuesday, June 25, 2013

What is Skew?

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Skew is defined as the difference in propagation delay between two or more signal paths.

Skew is of greatest concern  between two conductors of a differential pair.

If both path lengths aren’t matched precisely, skew in a  differential pair can lead to  increased Insertion Loss, Impedance Mismatch, Crosstalk and EMI.

Low skew between multiple paths can be important in a parallel bus.


http://www.sabritec.com/technotes/PDF/High_Speed_Digital_Tutorial.pdf
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What is Nyquist Frequency?

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http://www.dnr.state.oh.us/tabid/8170/Default.aspx

Nyquist Frequency

The Nyquist frequency is the bandwidth of a sampled signal, and is equal to half the sampling frequency of that signal. If the sampled signal should represent a continuous spectral range starting at 0 Hz, the Nyquist frequency is the highest frequency that the sampled signal can unambiguously represent.

Example

If a signal is sampled at 22050 Hz, the highest frequency that can be expected to be present in the sampled signal is 11025 Hz. Thus, to attain this expectation, the continuous signal should be run through a low-pass filter with a cut-off frequency below 11025 Hz; otherwise, the phenomenon of aliasing would be encounterd.
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Sunday, April 28, 2013

Thursday, March 28, 2013

FFT komutu kullanarak matlabda basit DFT

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clear all;
for n =1:20,
    sign1(n)=0.5*cos(2*pi*n/10); % transfer edilecek sinyal
end

XK(1:20)=0;
for k =1:20
    for n=1:20
    XK(k)=XK(k)+sign1(n)*exp(-j*2*pi*n*k/20); %matrisle transfer et
    end
end

%using fft command
XK2=fft(sign1,20); %fft komutu kullanarak transfer et
XK2(1)=[];
stem(XK); %cizdir
plot();
stem(XK2) %cizdir
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Wednesday, March 27, 2013

Great Windows tools

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http://rainmeter.net/cms/Final25
http://www.infoworld.com/d/applications/top-15-free-tools-every-windows-desktop-063?page=0,0
Microsoft synctoy 2.1


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Tuesday, March 26, 2013

Thursday, March 7, 2013

Simple DFT using FFT command in matlab

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clear all;
for n =1:20,
    sign1(n)=0.5*cos(2*pi*n/10); %sinal to convert, f=10 Hz
end

XK(1:20)=0;
for k =1:20
    for n=1:20
    XK(k)=XK(k)+sign1(n)*exp(-j*2*pi*n*k/20); %convert with math
    end
end

%using fft command
XK2=fft(sign1,20); %convert with command
XK2(1)=[];
stem(XK);
plot();
stem(XK2)

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Saturday, March 2, 2013

Simple Fourier Transform with Matlab - With Plots

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% SimpFourierTransform1
clear Q, f;
f=3;
h = @(x,y) sin(2*pi*x*f).*exp(-2*pi*i*x.*y);
mintime=-1;
maxtime=1;
tim1=linspace(mintime,maxtime,1000);


  figure()
  subplot(2,1,1), plot(tim1, real(h(tim1,f)));
  title('Real Part of Integrated Function')
  xlabel('Time (seconds)');
  ylabel('Magnitude or real part');
  subplot(2,1,2), plot(tim1, imag(h(tim1,f)));
  title('Imaginery Part of Integrated Function')
  xlabel('Time (seconds)');
  ylabel('Magnitude of imaginery part');


for f=1:20;
  Q(f) = quad(@(x)h(x,f),mintime,maxtime);
end
figure()
  subplot(2,1,1), stem(round(real(Q)));
  title('Real Part of the result of the integral')
  xlabel('F (1/seconds)');
  ylabel('Magnitude or real part');
  subplot(2,1,2), stem(round(imag(Q)));
  title('Imaginery Part of the result of the integral')
  xlabel('F (1/seconds)');
  ylabel('Magnitude of imaginery part');



%stem(abs(Q))

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Simple Fourier Transform With Matlab

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% SimpFourierTransform1
% Simple sin function with a frequency of 10 Hz, sin(2*pi*t*10)
% Multiply the function with basis transformer and integrate for a time interval


h = @(x,y) sin(2*pi*x*10).*exp(-2*pi*i*x.*y);

for f=1:20;
  Q(f) = quad(@(x)h(x,f),0,2);
end

stem(abs(Q))

 

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Friday, March 1, 2013

Simple Integral With Matlab

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%simple integral for notation

f = @(x) sin(x)./x
Q = quad(f,0,pi)

%another code to define a function and plot the result
f = @(x) sin(x)./x
t=linspace(-10*pi,10*pi,1000);
plot(t,f(t));
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Thursday, January 31, 2013

Cool tools

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http://www.linear.com/product/LT1302

Great circuit tool, model components they sell. Extensive librarires, nice graphs


PCB Artist from www.4pcb.com

Great board design tool, lets you draw whatever
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Friday, January 25, 2013

Thursday, January 24, 2013

third order intercept point

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http://en.wikipedia.org/wiki/Third-order_intercept_point
http://www.dynamicsciences.com/documents/24/DSI600-ApplicationNote-ThirdOrderInterceptPoint-OH-18May.pdf


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What's a compression point?

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http://www.microwaves101.com/encyclopedia/compressionpoint.cfm


What's a compression point?

For a linear device, output power is merely a fixed fraction of the input power. This includes most passive devices such as connectors, cable, waveguides, etc. Nonlinear devices exhibit complex behavior when input power is compared to output power. However, most nonlinear devices tend to become lossier with increasing input power. Devices such as amplifiers, mixers and switches tend to fall into this category.
At some power level, the gain response of the device will become reduced by a specific amount. This power level is said to be the compression point. Quite often, microwave engineers refer to the one-dB compression point, but two or three dB compression points are often important in power amplifier chains. Thus we refer to the quantities P1dB, P2dB, P3dB. In switches and other passives, you might hear reference to 0.25 dB compression point.
One general point about P1dB measurements that you should know: if you are working on a transmitter or exciter (or power amplifier), it is customary to specify the P1dB point at the output (abbreviated P1dBout). For a receiver (or low noise amp), the input P1dB point is often specified (abbreviated P1dBin). That being said, low noise amplifiers, the most critical component in a receiver chain, are most often specified with P1dB data measured at their output. If you are the receiver guy, you will need to calculate the worst-case P1dB at the input using the range of available gain that the part may provide.
Why do we talk about "gain" in a passive device such as a switch or a mixer, when obviously they have no gain? Because chances are components will become part of a larger chain, which will include amplification, and we want to be consistent.


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Monday, January 21, 2013

Sunday, January 13, 2013

Friday, January 11, 2013

Thursday, January 3, 2013