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jag vill har nagra kul saker....

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Robin P. Clark 2013-09-17 13:48:34 +01:00
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38
submission_thesis/CH5_Examples/copy.tex
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@ -22,7 +22,7 @@ this examines re-use of the potential divider {\dc} from section~\ref{subsec:pot
This amplifier is analysed twice, using different compositions of {\fgs}.
The two approaches, i.e. effects of choice of membership for {\fgs} are then discussed.
%\
fmmdglossOPAMP
\fmmdglossOPAMP
\item Section~\ref{sec:diffamp} analyses a circuit where two op-amps are used
to create a differencing amplifier.
Building on the two approaches from section~\ref{sec:invamp}, re-use of the non-inverting amplifier {\dc} from section~\ref{sec:invamp}
@ -53,6 +53,11 @@ by analysing a sigma delta ADC.
safety critical temperature sensor circuit, analysed for single and double failure mode scenarios.
\end{itemize}
\clearpage
\section{Example Analysis: Inverting OPAMP}
%
@ -66,6 +71,19 @@ safety critical temperature sensor circuit, analysed for single and double failu
\label{fig:invamp}
\end{figure}
%
Figure~\ref{fig:invamp} shows a standard configuration inverting amplifier.
A valid range for the output value of this circuit is assumed.
%
%Thus negative or low voltages can be considered as LOW
%and voltages higher than a given threshold considered as HIGH.
%
Because the amplifier inverts and the input is guaranteed positive any
output voltage above or equal to zero would be erroneous.
%
This would be an `$AMP_{HIGH}$' failure symptom.
%
A threshold would be determined for an `$AMP_{LOW}$' failure symptom (i.e. the output voltage more negative than expected). % error given the expected input range.
%
%This configuration is interesting from methodology pers.
There are two obvious ways in which this circuit can be modelled.
%
@ -100,17 +118,6 @@ In normal operation then, this is an inverted potential divider.
It must therefore be viewed as an inverted potential divider
and analysed as such; see table~\ref{tbl:pdneg}.
%
A valid range for the output value of this circuit is assumed.
%
%Thus negative or low voltages can be considered as LOW
%and voltages higher than a given threshold considered as HIGH.
%
Because the amplifier inverts and the input is guaranteed positive any
output voltage above or equal to zero would be erroneous.
%
This would be an $AMP_{HIGH}$ failure symptom.
%
A threshold would be determined for an $AMP_{LOW}$ failure symptom (i.e. the output voltage more negative than expected). % error given the expected input range.
%
\begin{table}[h+]
\caption{Inverted Potential divider: Single failure analysis}
@ -199,6 +206,7 @@ by forming a {\fg} with the OpAmp and the new {\dc} $IPD$.
\end{table}
%
%
\clearpage
%%This gives the same results as the analysis from figure~\ref{fig:invampanalysis}.
%
%
@ -303,7 +311,7 @@ by forming a {\fg} with the OpAmp and the new {\dc} $IPD$.
Failure modes for the {\dc} $INVAMP$ can be expressed thus;
%% $$ fm(INVAMP) = \{ {lowpass}, {high}, {low} \}.$$
$$ fm(INVAMP) = \{ HIGH, LOW, LOW PASS \} .$$
% \clearpage
A DAG is drawn representing the failure mode behaviour of
this amplifier (see figure~\ref{fig:invdag1}).
%
@ -311,8 +319,8 @@ Note that this allows failure symptoms to be traced back to causes, i.e.
to traverse from system level or top failure modes to base component failure modes.
%%%%% 12DEC 2012 UP to here in notes from AF email.
%
\clearpage
%
\clearpage
\subsection{Second Approach: Inverting OpAmp analysing with three components in one larger {\fg}}
\label{subsec:invamp2}
@ -368,7 +376,7 @@ This concern is re-visited in the differencing amplifier example in the next sec
\label{tbl:invamp}
\end{table}
\clearpage
%\clearpage
\subsection{Comparison between the two approaches}
\label{sec:invampcc}