diff --git a/mybib.bib b/mybib.bib index fe64b01..d8f817d 100644 --- a/mybib.bib +++ b/mybib.bib @@ -32,7 +32,12 @@ keywords = "single-fault", 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, AUTHOR = "Clifton Ericsson", TITLE = "Fault Tree Analysis a History", diff --git a/opamp_circuits_C_GARRETT/opamps.tex b/opamp_circuits_C_GARRETT/opamps.tex index b81fca3..d663c87 100644 --- a/opamp_circuits_C_GARRETT/opamps.tex +++ b/opamp_circuits_C_GARRETT/opamps.tex @@ -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, 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 -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. @@ -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 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. However, from a failure mode perspective we can analyse it in a very similar way 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} \end{table} - - - - 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 $fm(FivePoleLP) = \{ HIGH, LOW, FilterIncorrect, NO\_SIGNAL \}$. @@ -746,20 +742,6 @@ could be easily detected; the failure symptom $FilterIncorrect$ may be less obs - - - - - - - - - - - - - - \clearpage \section{Op-Amp circuit 3} @@ -774,15 +756,17 @@ could be easily detected; the failure symptom $FilterIncorrect$ may be less obs %\clearpage %\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 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. 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 {\fgs} and apply analysis from a failure mode perspective. + 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 $13.36=468$. 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). 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 -RFMEA for anything but trival systems. +process are by-hand/human activities. It can be seen that it is practically impossible to achieve +RFMEA for anything but trivial systems. % % Next statement needs alot of justification % @@ -1541,13 +1525,8 @@ For Functional Group 2 (FG2), let us map: FS6 & \mapsto & S5 \end{eqnarray*} -This - - - - -AUOMATIC chack can reveal WHEN double checking no longer necessary -in the hierarchy to cover dub sum !!!!! YESSSS:wq +This AUTOMATIC check can reveal WHEN double checking no longer necessary +in the hierarchy to cover dub sum !!!!! YESSSS % does not cover what weird side effect may occur though, but then the {\fg} was not modelled correctly in the first place... diff --git a/related_papers_books/Analog_applications_AUG2000_BUBBA_aug_07.pdf b/related_papers_books/Analog_applications_AUG2000_BUBBA_aug_07.pdf new file mode 100644 index 0000000..02eba6e Binary files /dev/null and b/related_papers_books/Analog_applications_AUG2000_BUBBA_aug_07.pdf differ