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Low Noise Amplifier

Question asked by karthik001 on Apr 3, 2016
Latest reply on Apr 5, 2016 by aehoward

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In our LNA design the S-parameters S(1,2) and S(2,1) are similar and both are negative.Is there any specific method to obtain S-parameters. In this design we have used MOSFET_PMOS and MOSFET_NMOS from the RF library.We are new to this software please help.
In this design we are getting the forward gain s(2,1) as negative instead of positve value.Please specify the procedure to get the positive value.

Edited by: karthik001 on Apr 4, 2016 1:30 AM

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aehoward Apr 4, 2016 9:27 AM
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I recommend looking at the device I-V curves and making sure you have biased it correctly. You could use some of the schematics in the Amplifier DesignGuide to look at gain, noise, and stability circles. From any schematic select DesignGuide > Amplifier > DC and Bias Point Simulations > ...
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- karthik001 @ aehoward on Apr 5, 2016 4:38 AM
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  We checked the I-V curve using FET curve tracer. How do we use these values in LNA schematic in order to get positive gain.
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  - LNA Schematic.png106.3 KB
  - NMOS schematic.png167.3 KB
  - NMOS bias characteristics.png111.2 KB
  - PMOS bias characteristics.png110.9 KB
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  - aehoward @ karthik001 on Apr 5, 2016 8:36 AM
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    Your I-V curves do not look correct. Your NMOS device only has pA, and your PMOS device has Amps, and the gate bias has no effect.
    You could look at the DC bias voltages and currents on the schematic. Are you working with a Keysight application engineer?
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Low Noise Amplifier

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