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for the IF frequency up to 140MHz quadrature modulator, I recommend you try AD9777/9778/9779 family DAC, which can be used to produce a High IF signal up to 200MHz. You can implement quadrature modulation in digital domain in FPGA then feed the digital stream into DAC.
For demodulator, you...
Hi, you may try ADL5370. It's a type of direct quadrature modulator can be used in Zero-IF system. Features includes,
Very low noise floor=-158dBm/Hz@Pout=+5dBm
High linearity: OIP3=+26dBm
excellent uncalibrated LO feedthrough <-45dBc
excellent uncalibrated sideband supression <-47dBc
32768 crystal oscilator
You may try in the following way:
give an initial current for the serial inductance in crystal model, say a few microamps, then do what you did before.
The most important reason that optic fibre has much higher bandwidth is, simply saying, the carrier on optic fibre is light, which frequency is so high to reach 10^14 Hz. if we just take a mall amount of the carrier frequency(modulation), say 0.05%, it would be 50GHz, that's the case in DWDM...
rms to dc converter
FYI.
If the sinput sigal is a periodic one, there is a simple way to convert its rms value to DC describing as following:
Employ an AC amplifier to amply the input signal to make sure the output level is above 0.7v, higher amplitude is better. The amplified large signal...
ad623 problem
What does the iteration exactlly mean? What about the model of AD623? Is it the one you downloaded on ADI's website?
Can you post your the waveforms at output pin of the amplifier? Otherwise it's quite difficult to do further analysis.
hierarchy orcad
Hi Ringo234,
You may try to search a key word like "hierarchy" in the online documentations, which can be launched by clicking "windows start menu->programs->Orcad->online documents" . I'm sorry I forgot in which document you need to search. I'll tell you the details later...
pspice behavior
Hi everybody,
I encounted a strange phenomena when I did simulation of an ALC(automatic level control) loop using Orcad/pspice 9.1 simulator. Roughly saying, the transient simulation results are dramatically different with different settings of simulator, they are quite...
phase noise jitter conversion
Probably you haven't fully understood the method described in Ken's paper. I think you calculated the close-in noise as the wide-band noise which can be predicted by the simple equation Peff=noise power density * Bandwidth.
In fact, for close in phase noise, the...
Power Amplifier
Do you have proper input and output match networks for the transistor? Do you have proper power supply decoupling circuitry? Try to add more grounded points on the PCB. You should know the gain of a transistor at low frequency(say 100MHz) is pretty much higher than at high...
Generally, the main hightlights of a Schottky diode are faster switched time, lower voltage drop. The drawbacks are higher reverse leakage current, lower reverse broken voltage.
In switched mode power supply applications, Schottky diode if often used in case of low voltage high current...
Additional question,
Suppose I have a RC oscillator, for each C value, I can get the waveform by the transient analysis. How can I get a curve on which x axias is the value of C, y axias is the period of the output waveform.
If I do the parametric sweep upon primary transient analysis, I can...
You can use the command .ic to initialize the current flow through the effective inductance of the quartz model,thus the circuit may works quickly to reach the stable amplitude.
Why should you initialize the current? As you might know,the Qulity value of a quartz is very high,normally it's...
Re: Do photodiode in different wavelength affect circuit des
That dosen't matter. The difference is only the responsivity different in different wavelength,e.g, 0.85A/W@1310nm, -.95A/W@1550nm.
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