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Entry  Tue Jul 31 15:24:53 2012, Yaakov, Update, STACIS, Open loop gains and block diagram z_OL.figz_OL.bmpx_OL.bmpstacis_block.bmpx_OL.fig
    Reply  Tue Jul 31 19:34:55 2012, Koji, Update, STACIS, Open loop gains and block diagram 
Message ID: 7061     Entry time: Tue Jul 31 19:34:55 2012     In reply to: 7058
Author: Koji 
Type: Update 
Category: STACIS 
Subject: Open loop gains and block diagram 

With your definition of the open loop gain, G=+1 is the condition to have singularity in a closed loop transfer function 1/(1-G).

But this is not the sole criteria of the loop stability.
Basically, the closed loop transfer function should not have "unphysical" pole.
For more about loop instability, you should refer stability criteria in literature such as Nyquist's stability criterion.

Both of the X and Z loops look unstable with the current gain.

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