Recent content by Fovakis

http://i1284.photobucket.com/albums/a578/fovos1/SISOFILTE_zps56bc4977.png I don't want this filter to PASS any dc signal , because at the next stage there is a demodulator. So i need to cut the dc signal that maybe leakage from other stages to the input of my active filter. My circuit is...

Yes it is a low pass filter the first stage. the second is an amp. :-p

yes you right about that. what simulator can i use for that? Is there any tool or toturial to find out? Also, if i want to calculate the Zin for f=20khz. it would be much better to do the maths i guess. I am starting, first a Capacitor with Zc=1/j2πfC1..8/j Farads. Is it right to do...

can i have more help please..

Hi AlephZero ! thanks! i am a begginer so please more simple the explanations if you can :( First of all i understand that Zout is Zoutput of Operation Amplifier + pluse Zof capacitor=1/jωC where C=10^(-6)Farad. (basically i have a dual fet OPA2608 not the LM358 that is at the schematic)...

yeah exactly this ! :) Hi and many thanks for your reply! I will give more information about my question on the schematic. So the frequency bandwidth is DC to 17khz (audio)! Before this filter there is a double balanced ring diode mixer that downconvert a signal of 30MHz to a baseband DC...

Hi! i want to calculate the Rinput and Routput of this Active Filter. How can i do that? "][/URL]

Yes you have right.The 2462 and 2522 (image freq) are going into my filter (from the TX_). The image freq is about 20dB Lower that the desired in my case. But in both senarios this image freq exists. i don't have a directional coupler in my lab, but i have a network analyser, so i can see the...

Thanks for the reply. 1.First i don't understand what is the input and what is the output port!There is no label that explain me what is each port (!). Is there any difference? About the matching i will check it with a network analyser better, maybe? 2. What do you mean is this way?What...

Yes it is tuned in the right no prob with that.

"][/URL]Hi to all, i have a SISO system with microwaves devices. The 16-QAM information is about 20KHz , upconverted at 30 MHz and then at 2462MHz.At the receiver the same procedure, downconverting. After the first LNA i have a BPF fc=2430MHz which has large Bandwidth so it does not protect...

So many thanks about your help friends. It is so important really thanks! So about my experiment i want to measure S/N .. about the noise ,activate noise marker on and what setting maybe i will make to be close to theory? RBW=20KHZ ?is this good or larger or smaller ?my signals's bandwidth...

Hi ! i am confused because the NF of s.a is different with noise marker on and off?both attenuation 0dBm and 50 ohm terminal at s.a input. 1)with noise marker on; -150dBm/hz=-174+NFs.a => NFs.a=24dBm ? 2)with noise marker off: -113 dbm = -174 +10log(RBW=1KHz)=30 +NFs.a=>NFs.a=30dBm...

with noise market -150dBm. how this came from? -174dBm +NFs.a=-150dBm so the NF~24dBm? this is not right i believe. but how can i find the NF of my s.a to do the maths to estimate the NFtotal

Νο problem about the delay many thanks for the help! I did again the experiment so i notice that: the noise of S.A at RBW=1KHZ and 0 atten is: -113 to -123 not stable. With LNA added goes to -90dBm. With noise market without LNA is:-149 to -150 dBm and with LNA goes to -128dBm. Now is...