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Problem when using RFDE momentum blocks in Cadence (Drop across Resistance w/o any current)

dipal261

Hi,

I have a problem with the use of RFDE mom symbol view in Cadence schematic. The image is attached below for reference. The momentum block is basically a MOM capacitor for coupling ac input . In theory, there should not be any drop in the 3KOhms resistance connected to the gate of the transistor in one end and the capacitor on the other end. This entire block works fine if I simply remove the MOM model with an ideal capacitor from analoglib. In that case, I see no drop across the 3K Ohms resistance. But when using the MOM model, it simply destroys any gate biasing that I try to put. What is the problem here? and how can I get a work around it?

This is a dc analysis and shows the current and voltage at each node.

Thank you.

 

Regards

Dipal

Parents

  • Hi Andrew,

    This is a fresh simulation where I removed everything else. I am using ADS 2016.01, MMSIM15.10.627 and IC6.17.704

    Here is the spectre simulator data from the input.scs file for the below schematic

    PORT0 (net70 0) port r=50 num=1 type=sine freq=100G dbm=0

    R3 (net70 net03) resistor r=1u

    R2 (net06 net42) resistor r=1u

    R1 (net42 net010) resistor r=3K

    R0 (Amp_Vdd Drain_device) resistor r=100

    V4 (net010 0) vsource dc=550.00m type=dc

    V0 (Amp_Vdd 0) vsource dc=Vdd type=dc

    I405 ( net03 0 0 0 net06 0 0 0) nport interp=linear \

           file="workdir/mommdl/text.txt" \

           datafmt=citi

    and the mommdl/text.text file is an S parameter file generated for the momentum block I405 (schematic below)

    Please let me know if you need any other data.

    Thank you.

    Regards

    Dipal

Reply

  • Hi Andrew,

    This is a fresh simulation where I removed everything else. I am using ADS 2016.01, MMSIM15.10.627 and IC6.17.704

    Here is the spectre simulator data from the input.scs file for the below schematic

    PORT0 (net70 0) port r=50 num=1 type=sine freq=100G dbm=0

    R3 (net70 net03) resistor r=1u

    R2 (net06 net42) resistor r=1u

    R1 (net42 net010) resistor r=3K

    R0 (Amp_Vdd Drain_device) resistor r=100

    V4 (net010 0) vsource dc=550.00m type=dc

    V0 (Amp_Vdd 0) vsource dc=Vdd type=dc

    I405 ( net03 0 0 0 net06 0 0 0) nport interp=linear \

           file="workdir/mommdl/text.txt" \

           datafmt=citi

    and the mommdl/text.text file is an S parameter file generated for the momentum block I405 (schematic below)

    Please let me know if you need any other data.

    Thank you.

    Regards

    Dipal

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