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vcvs Impedance Dips in Frequency

ChrisDG

Hello,

I am trying to create a near ideal voltage buffer using the components of analogLib. I have tried using vcvs and other controlled sources. All these perform the function correctly but always have sharp frequency spikes and dips in the input and output impedances. I can understand if the spikes are insignificant but some of these come to around 90% of the maximum impedance value so when placed in actual circuits it affects the performance at these frequency notches. I have tried using feedback Rs and Cs but they don't seem to help.

Attached below is one example of vcvs under 2port SP analysis where Z11 is shown.

The port settings are:

Port1: Resistance=50ohm; SourceType=Sine; PortNum=1

Port2: Resistance=50ohm; SourceType=DC; PortNum=2

Simulator: Spectre
SP Analysis: 10M 10GHz ; Single-Ended

Wondered if anyone could recommend a solution.

Thanks.

Chris

Parents
  • ChrisDG

    Please find  output below .

    Cadence (R) Virtuoso (R) Spectre (R) Circuit Simulator
    Version 13.1.1.252.isr11 64bit -- 14 Aug 2014
    Copyright (C) 1989-2014 Cadence Design Systems, Inc. All rights reserved worldwide. Cadence, Virtuoso and Spectre are registered trademarks of Cadence Design Systems, Inc. All others are the property of their respective holders.
    Includes RSA BSAFE(R) Cryptographic or Security Protocol Software from RSA Security, Inc.

    input.scs file is attached. (The attachment window does not accept .scs files so renamed to .doc. The file itself is unchanged)

    Please let me know if you need anything else. 

    Many Thanks.

    Chris.

    input.doc

Reply
  • ChrisDG

    Please find  output below .

    Cadence (R) Virtuoso (R) Spectre (R) Circuit Simulator
    Version 13.1.1.252.isr11 64bit -- 14 Aug 2014
    Copyright (C) 1989-2014 Cadence Design Systems, Inc. All rights reserved worldwide. Cadence, Virtuoso and Spectre are registered trademarks of Cadence Design Systems, Inc. All others are the property of their respective holders.
    Includes RSA BSAFE(R) Cryptographic or Security Protocol Software from RSA Security, Inc.

    input.scs file is attached. (The attachment window does not accept .scs files so renamed to .doc. The file itself is unchanged)

    Please let me know if you need anything else. 

    Many Thanks.

    Chris.

    input.doc

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