robin/Robin_PHD
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

ref to analog apps journal for bubba oscillator

Browse Source
This commit is contained in:
Robin Clark 2012-01-07 13:54:14 +00:00
parent e5d640f217
commit 838a212b1e
3 changed files with 15 additions and 31 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
mybib.bib
View File

@ -32,7 +32,12 @@
keywords = "single-fault", keywords = "single-fault",
keywords = "fault-tolerance" keywords = "fault-tolerance"
} }
@ARTICLE{bubba,
AUTHOR = "Ron Mancini",
TITLE = "Design of OP-Amp sine wave oscillators",
JOURNAL = "Analog Applications Journal: Texas Instruments: August",
YEAR = "2000"
}
@ARTICLE{ftahistory, @ARTICLE{ftahistory,
AUTHOR = "Clifton Ericsson", AUTHOR = "Clifton Ericsson",
TITLE = "Fault Tree Analysis a History", TITLE = "Fault Tree Analysis a History",

39
opamp_circuits_C_GARRETT/opamps.tex
View File

@ -494,7 +494,7 @@ The circuit in figure~\ref{fig:circuit2} shows a five pole low pass filter.
Starting at the input, we have a first order low pass filter buffered by an op-amp, Starting at the input, we have a first order low pass filter buffered by an op-amp,
the output of this is passed to a Sallen~Key~\cite{aoe}[p.267] second order lowpass filter. the output of this is passed to a Sallen~Key~\cite{aoe}[p.267] second order lowpass filter.
The output of this is passed into another Sallen~Key filter -- which although it may have different values The output of this is passed into another Sallen~Key filter -- which although it may have different values
for its resistors/capacitors and thus have a different frequency response -- is idential from a failure mode perspective. for its resistors/capacitors and thus have a different frequency response -- is identical from a failure mode perspective.
Thus we can analyse the first Sallen~Key low pass filter and re-use the results. Thus we can analyse the first Sallen~Key low pass filter and re-use the results.
@ -518,7 +518,7 @@ a more sophisticated low pass filter.
% %
R10 and C10 act as a potential divider, with the crucial difference between a purely resistive potential divider being R10 and C10 act as a potential divider, with the crucial difference between a purely resistive potential divider being
that the impedance of the capacitor is lower for higher frequencies. that the impedance of the capacitor is lower for higher frequencies.
Thus higher frquencies are attenuated at the point that we Thus higher frequencies are attenuated at the point that we
read its output signal. read its output signal.
However, from a failure mode perspective we can analyse it in a very similar way However, from a failure mode perspective we can analyse it in a very similar way
to a potential divider (see section~\ref{potdivfmmd}). to a potential divider (see section~\ref{potdivfmmd}).
@ -728,10 +728,6 @@ We represent the desired FMMD hierarchy in figure~\ref{fig:circuit2h}.
\label{tbl:fivepole} \label{tbl:fivepole}
\end{table} \end{table}
We now can create a {\dc} to represent the circuit in figure~\ref{fig:circuit2}, we can call it We now can create a {\dc} to represent the circuit in figure~\ref{fig:circuit2}, we can call it
$FivePoleLP$ and applying the $fm$ function to it (see table~\ref{tbl:fivepole}) yields $fm(FivePoleLP) = \{ HIGH, LOW, FilterIncorrect, NO\_SIGNAL \}$. $FivePoleLP$ and applying the $fm$ function to it (see table~\ref{tbl:fivepole}) yields $fm(FivePoleLP) = \{ HIGH, LOW, FilterIncorrect, NO\_SIGNAL \}$.
@ -746,20 +742,6 @@ could be easily detected; the failure symptom $FilterIncorrect$ may be less obs
\clearpage \clearpage
\section{Op-Amp circuit 3} \section{Op-Amp circuit 3}
@ -774,15 +756,17 @@ could be easily detected; the failure symptom $FilterIncorrect$ may be less obs
%\clearpage %\clearpage
%\section{Standard Non-inverting OP AMP} %\section{Standard Non-inverting OP AMP}
This circuit is described in the Analog Applications Journal~\cite{bubba}. This circuit is described in the Analog Applications Journal~\cite{bubba}[p.37].
The circuit uses four 45 degree phase shifts, and an inverting amplifier to provide The circuit uses four 45 degree phase shifts, and an inverting amplifier to provide
gain and the final 180 degrees of phase shift (making a total of 360 degrees of phase shift). gain and the final 180 degrees of phase shift (making a total of 360 degrees of phase shift).
From a fault finding perspective this circuit is less than ideal. From a fault finding perspective this circuit is less than ideal.
The signal path is circular (its a positive feedback circuit) and most failures would simply cause the output to stop oscillating. The signal path is circular (its a positive feedback circuit) and most failures would simply cause the output to stop oscillating.
The top level failure modes for the FMMD hierarchy bear this out.
However, FMMD is a bottom -up analysis methodology and we can therefore still identify However, FMMD is a bottom -up analysis methodology and we can therefore still identify
{\fgs} and apply analysis from a failure mode perspective. {\fgs} and apply analysis from a failure mode perspective.
If we were to analyse this circuit without modularisation, we have 14 components with If we were to analyse this circuit without modularisation, we have 14 components with
($4.4 +10.2 = 36$) failure modes . Applying equation~\ref{eqnrd2} gives a complexity comparison figure of $13.36=468$. ($4.4 +10.2 = 36$) failure modes . Applying equation~\ref{eqnrd2} gives a complexity comparison figure of $13.36=468$.
The reduce the complexity required to analyse this circuit we apply FMMD and start by determining {\fgs}. The reduce the complexity required to analyse this circuit we apply FMMD and start by determining {\fgs}.
@ -1316,8 +1300,8 @@ Rigorous FMEA (RFMEA).
The computational order for RFMEA would be polynomial ($O(N^2.K)$) (where $K$ is the variable number of failure modes). The computational order for RFMEA would be polynomial ($O(N^2.K)$) (where $K$ is the variable number of failure modes).
This order may be acceptable in a computational environment: However, the choosing of {\fgs} and the analysis This order may be acceptable in a computational environment: However, the choosing of {\fgs} and the analysis
process are human activities. It can be seen that it is practically impossible to achieve process are by-hand/human activities. It can be seen that it is practically impossible to achieve
RFMEA for anything but trival systems. RFMEA for anything but trivial systems.
% %
% Next statement needs alot of justification % Next statement needs alot of justification
% %
@ -1541,13 +1525,8 @@ For Functional Group 2 (FG2), let us map:
FS6 & \mapsto & S5 FS6 & \mapsto & S5
\end{eqnarray*} \end{eqnarray*}
This This AUTOMATIC check can reveal WHEN double checking no longer necessary
in the hierarchy to cover dub sum !!!!! YESSSS
AUOMATIC chack can reveal WHEN double checking no longer necessary
in the hierarchy to cover dub sum !!!!! YESSSS:wq
% does not cover what weird side effect may occur though, but then the {\fg} was not modelled correctly in the first place... % does not cover what weird side effect may occur though, but then the {\fg} was not modelled correctly in the first place...

BIN
related_papers_books/Analog_applications_AUG2000_BUBBA_aug_07.pdf Normal file
View File

Binary file not shown.