Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

BPSK Modulator for RFID measurement problem

Status
Not open for further replies.
However, i unable to measure the modulated signal.
Click to expand...
Do you see any reason, why the circuit should operate as a modulator? I assume a drawing error.
 

Why M2 is shorting the output? According to the journal, M2 works as a resistor so that negligible power at antenna goes to modulator.

I feed a carrier (900MHz) at Cout and i measure my output at the same point using bi-port. Is the way i measure wrong or correct?

Thanks.
 

I think you should use a model of your antenna (probably an RLC), connected in parallel to Cout, receiving the carrier frequency (900 MHz). Then you should measure the scattered signal by means of a directional coupler.
 

    W

    wing0

    Points: 2
    Helpful Answer Positive Rating
The RLC circuit for antenna model is series RLC or parallel RLC?

I am using Mentor Graphics for my simulation. Can I know how to construct the directional coupler in Mentor Graphics?
 

It depends from the antenna type you are going to use: an open dipole can be seen as a series RLC, a loop antenna, insetead, by means of a parallel RLC. These models are a first oredr approximation of the actual model and are valid close to the resonance. I never used mentor Graphic simulator, so I don't know how to model a directional coupler. I'm thinkink, if you can use an alternative method.
 

    W

    wing0

    Points: 2
    Helpful Answer Positive Rating
Is it the output waveform correct?
I measured the waveform between the antenna model and the modulator.

 

The waveform is in principle quite correct, beacuse you have a phase reversal at each transition, but it seems that there is some amplitude issue. Just a couple of things:

1) the data-rate, in your simulation, is very high: the same as the carrier frequency. I think you should reduce it to have a better idea about amplitude distortion when the transition occours.

2) If you send to the modulator pseudo-random datas, instead of a clock, you should be able to see also the eye-diagram using accumulated plots.

Regards.
 

    W

    wing0

    Points: 2
    Helpful Answer Positive Rating
I used a lower data rate for my simulation. I found out that the amplitude is overshoot at the transitions.
How to overcome the amplitude problem?

 

The edges of you data signal are very sharp. I think a transmission filter should be used on data before they are sent to the modulator. You can just try to slow the rise/fall time of the data generator in your simulation. You can also try to reduce the Q of the system putting a low-value resistor in series to the antenna.
Regards.
 

    W

    wing0

    Points: 2
    Helpful Answer Positive Rating
Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top