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diff --git a/ffi/n5.lyx b/ffi/n5.lyx new file mode 100644 index 0000000..5b5a503 --- /dev/null +++ b/ffi/n5.lyx @@ -0,0 +1,1246 @@ +#LyX 2.3 created this file. For more info see http://www.lyx.org/ +\lyxformat 544 +\begin_document +\begin_header +\save_transient_properties true +\origin unavailable +\textclass book +\begin_preamble +\usepackage{circuitikz} +\end_preamble +\use_default_options true +\maintain_unincluded_children false +\language spanish +\language_package default +\inputencoding auto +\fontencoding global +\font_roman "default" "default" +\font_sans "default" "default" +\font_typewriter "default" "default" +\font_math "auto" "auto" +\font_default_family default +\use_non_tex_fonts false +\font_sc false +\font_osf false +\font_sf_scale 100 100 +\font_tt_scale 100 100 +\use_microtype false +\use_dash_ligatures true +\graphics default +\default_output_format default +\output_sync 0 +\bibtex_command default +\index_command default +\paperfontsize default +\spacing single +\use_hyperref false +\papersize default +\use_geometry false +\use_package amsmath 1 +\use_package amssymb 1 +\use_package cancel 1 +\use_package esint 1 +\use_package mathdots 1 +\use_package mathtools 1 +\use_package mhchem 1 +\use_package stackrel 1 +\use_package stmaryrd 1 +\use_package undertilde 1 +\cite_engine basic +\cite_engine_type default +\biblio_style plain +\use_bibtopic false +\use_indices false +\paperorientation portrait +\suppress_date false +\justification true +\use_refstyle 1 +\use_minted 0 +\index Index +\shortcut idx +\color #008000 +\end_index +\secnumdepth 3 +\tocdepth 3 +\paragraph_separation indent +\paragraph_indentation default +\is_math_indent 0 +\math_numbering_side default +\quotes_style swiss +\dynamic_quotes 0 +\papercolumns 1 +\papersides 1 +\paperpagestyle default +\tracking_changes false +\output_changes false +\html_math_output 0 +\html_css_as_file 0 +\html_be_strict false +\end_header + +\begin_body + +\begin_layout Standard +\begin_inset ERT +status open + +\begin_layout Plain Layout + + +\backslash +def +\backslash +representnode#1{ +\backslash +begin{circuitikz} +\backslash +draw (0,0) node[#1]{}; +\backslash +end{circuitikz}} +\end_layout + +\begin_layout Plain Layout + + +\backslash +def +\backslash +shownode#1{ +\backslash +begin{center} +\backslash +representnode{#1} +\backslash +end{center}} +\end_layout + +\end_inset + + +\end_layout + +\begin_layout Standard +Un +\series bold +amplificador operacional +\series default + es un tipo de amplificador diferencial usado junto con componentes pasivos + para sumar, restar, integrar, derivar, etc. + Tiene dos terminales de entrada, una no inversora y otra inversora; un + terminal de salida, y dos terminales para alimentación +\begin_inset Formula $+V_{cc}$ +\end_inset + + y +\begin_inset Formula $-V_{cc}$ +\end_inset + +. + La tensión en cada uno debe ser constante y de signo opuesto al otro, pero + no tienen por qué ser tensiones opuestas. + Si lo son decimos que la alimentación es +\series bold +simétrica +\series default +, y de lo contrario es +\series bold +asimétrica +\series default +. +\end_layout + +\begin_layout Standard +\begin_inset ERT +status open + +\begin_layout Plain Layout + + +\backslash +begin{center} +\end_layout + +\begin_layout Plain Layout + + +\backslash +begin{circuitikz} +\end_layout + +\begin_layout Plain Layout + + +\backslash +draw (0,0) node(oa)[op amp]{} +\end_layout + +\begin_layout Plain Layout + +(oa.+) node[left]{$v_+$} (oa.-) node[left]{$v_-$} +\end_layout + +\begin_layout Plain Layout + +(oa.up) node[vcc]{$+V_{cc}$} (oa.down) node[vee]{$-V_{cc}$} +\end_layout + +\begin_layout Plain Layout + +(oa.out) node[right]{$v_{out}$}; +\end_layout + +\begin_layout Plain Layout + + +\backslash +end{circuitikz} +\end_layout + +\begin_layout Plain Layout + + +\backslash +end{center} +\end_layout + +\end_inset + + +\end_layout + +\begin_layout Standard +Dos zonas de funcionamiento: +\end_layout + +\begin_layout Itemize + +\series bold +Lineal +\series default +: +\begin_inset Formula $-V_{cc}<V_{out}<+V_{cc}$ +\end_inset + +. +\end_layout + +\begin_layout Itemize + +\series bold +Saturación +\series default +: +\begin_inset Formula $V_{out}=+V_{cc}$ +\end_inset + + ó +\begin_inset Formula $V_{out}=-V_{cc}$ +\end_inset + +. +\end_layout + +\begin_layout Standard +Su función es +\begin_inset Formula $v_{out}=A_{V}(v_{+}-v_{-})$ +\end_inset + +, donde +\begin_inset Formula $v_{+}$ +\end_inset + + es la entrada no inversora y +\begin_inset Formula $v_{-}$ +\end_inset + + la inversora. + Llamamos +\series bold +tensión de entrada diferencial +\series default + a +\begin_inset Formula $v_{in}:=v_{+}-v_{-}$ +\end_inset + +, de modo que +\begin_inset Formula $v_{out}=A_{V}\cdot v_{in}$ +\end_inset + +; +\series bold +ganancia diferencial +\series default + a +\begin_inset Formula $A_{d}:=A_{V}$ +\end_inset + +, y +\series bold +tensión de entrada de modo común +\series default + a +\begin_inset Formula $v_{icm}:=\frac{v_{+}+v_{-}}{2}$ +\end_inset + +. + La variación de la tensión de salida en el tiempo está limitada por el + +\series bold +\emph on +slew-rate +\series default +\emph default +, +\begin_inset Formula $SR:=\max\left\{ \frac{dv_{out}}{dt}\right\} $ +\end_inset + +. +\end_layout + +\begin_layout Standard +Los AO contienen circuitos de entrada acoplados en continua, y la corriente + entra y sale de los terminales de entrada del AO. + En el caso real, las corrientes de polarización (?) no son iguales, lo + que crea una +\series bold +corriente de desviación +\series default + +\begin_inset Formula $I_{off}:=I_{B^{+}}-I_{B^{-}}$ +\end_inset + +. + También puede haber una tensión de salida distinta de cero para una tensión + de entrada nula ( +\series bold +\emph on +offset voltage +\series default +\emph default +). +\end_layout + +\begin_layout Standard +La +\series bold +realimentación +\series default + es la conexión de una señal de salida con alguna de las entradas. +\end_layout + +\begin_layout Itemize + +\series bold +Realimentación positiva +\series default +: Cuando se hace a la entrada no inversora. + Resulta en circuitos inestables que rápidamente se saturan. +\end_layout + +\begin_layout Itemize + +\series bold +Realimentación negativa +\series default +: Cuando se hace a la entrada inversora. + La ganancia se reduce respecto al valor en lazo abierto y el circuito es + más estable. +\end_layout + +\begin_layout Standard +Un AO (amplificador operacional) ideal tiene +\begin_inset Formula $Z_{in}=+\infty$ +\end_inset + +, +\begin_inset Formula $A_{V_{0}}=+\infty$ +\end_inset + +, +\begin_inset Formula $G=0$ +\end_inset + +, +\begin_inset Formula $Z_{out}=0$ +\end_inset + +, ancho de banda +\begin_inset Formula $W_{D}=+\infty$ +\end_inset + + y ausencia de desviación de características con la temperatura. + Con esto se facilitan los cálculos, pues como +\begin_inset Formula $Z_{in}=+\infty$ +\end_inset + +, las corrientes de entrada se pueden considerar nulas, y si existe realimentaci +ón negativa podemos considerar que, siempre que no se llegue a la zona de + saturación, las dos entradas se encuentran al mismo potencial, situación + a la que llamamos +\series bold +cortocircuito virtual +\series default +. + Esto se debe a que la ganancia es tan elevada que una pequeña tensión diferenci +al entre las entradas saturaría la salida, y al realimentar negativamente, + si las tensiones se desequilibran, la realimentación negativa compensa + esta diferencia. +\end_layout + +\begin_layout Section +Circuitos con AO +\end_layout + +\begin_layout Subsection +Amplificador inversor +\end_layout + +\begin_layout Standard +\begin_inset ERT +status open + +\begin_layout Plain Layout + + +\backslash +begin{center} +\end_layout + +\begin_layout Plain Layout + + +\backslash +begin{circuitikz} +\end_layout + +\begin_layout Plain Layout + + +\backslash +draw (0,0) node(OA)[op amp]{} +\end_layout + +\begin_layout Plain Layout + +(OA.+) -- ++(0,-1) node(G)[ground]{} +\end_layout + +\begin_layout Plain Layout + +(OA.-) to[R=$R_1$] ++(-2,0) to[american voltage source,l=$v_{in}$] ($(OA.- + |- G) + (-2,0)$) -- (G) +\end_layout + +\begin_layout Plain Layout + +(OA.-) -- ++(0,1) to[R=$R_2$] ($(OA.out |- OA.-) + (0,1)$) -- (OA.out) -- ($(OA.out)+ +(.5,0)$) to[R=$R_L$] ($(OA.out |- G) + (.5,0)$) -- (G); +\end_layout + +\begin_layout Plain Layout + + +\backslash +end{circuitikz} +\end_layout + +\begin_layout Plain Layout + + +\backslash +end{center} +\end_layout + +\end_inset + + +\end_layout + +\begin_layout Standard +Tenemos en cuenta que +\begin_inset Formula $V_{+}=V_{-}=0$ +\end_inset + + y las leyes de Kirchhoff. + Como +\begin_inset Formula $I_{-}=0$ +\end_inset + +, toda la corriente pasa por +\begin_inset Formula $R_{2}$ +\end_inset + +, luego +\begin_inset Formula $i_{1}=i_{2}$ +\end_inset + +, es decir, +\begin_inset Formula $\frac{v_{in}-v_{-}}{R_{1}}=\frac{v_{-}-v_{out}}{R_{2}}$ +\end_inset + + con +\begin_inset Formula $v_{-}=0$ +\end_inset + +, y por tanto +\begin_inset Formula $v_{out}=-v_{in}\frac{R_{2}}{R_{1}}$ +\end_inset + + y +\begin_inset Formula $A_{V}=-\frac{R_{2}}{R_{1}}$ +\end_inset + +. +\end_layout + +\begin_layout Subsection +Amplificador no inversor +\end_layout + +\begin_layout Standard +\begin_inset ERT +status open + +\begin_layout Plain Layout + + +\backslash +begin{center} +\end_layout + +\begin_layout Plain Layout + + +\backslash +begin{circuitikz} +\end_layout + +\begin_layout Plain Layout + + +\backslash +draw (0,0) node(OA)[op amp,yscale=-1]{} +\end_layout + +\begin_layout Plain Layout + +(OA.-) -- ++(0,-1) to[R=$R_1$] ++(0,-2) node(G)[ground]{} +\end_layout + +\begin_layout Plain Layout + +(OA.+) -- ++(-2,0) to[american voltage source,l=$v_{in}$] ($(OA.+ |- G) + + (-2,0)$) -- (G) +\end_layout + +\begin_layout Plain Layout + +(OA.out) -- ($(OA.out |- OA.-)+(0,-1)$) to[R=$R_2$] ($(OA.-)+(0,-1)$) +\end_layout + +\begin_layout Plain Layout + +(OA.out) -- ($(OA.out)+(1,0)$) to[R=$R_L$] ($(OA.out |- G)+(1,0)$) -- (G); +\end_layout + +\begin_layout Plain Layout + + +\backslash +end{circuitikz} +\end_layout + +\begin_layout Plain Layout + + +\backslash +end{center} +\end_layout + +\end_inset + + +\end_layout + +\begin_layout Standard +Tenemos que +\begin_inset Formula $v_{-}=v_{+}=v_{in}$ +\end_inset + +, y que +\begin_inset Formula $i_{-}=i_{+}=0$ +\end_inset + + y por tanto +\begin_inset Formula $i_{1}=i_{2}$ +\end_inset + +. + Pero +\begin_inset Formula $i_{1}=\frac{v_{-}}{R_{1}}=\frac{v_{in}}{R_{1}}$ +\end_inset + +, luego +\begin_inset Formula $v_{out}=i_{1}(R_{1}+R_{2})=v_{in}\left(1+\frac{R_{2}}{R_{1}}\right)$ +\end_inset + + y +\begin_inset Formula $A_{V}=\frac{V_{out}}{V_{in}}=1+\frac{R_{2}}{R_{1}}$ +\end_inset + +. +\end_layout + +\begin_layout Subsection +Seguidor de tensión +\end_layout + +\begin_layout Standard +\begin_inset ERT +status open + +\begin_layout Plain Layout + + +\backslash +begin{center} +\end_layout + +\begin_layout Plain Layout + + +\backslash +begin{circuitikz} +\end_layout + +\begin_layout Plain Layout + + +\backslash +draw (0,0) node(OA)[op amp,yscale=-1]{} +\end_layout + +\begin_layout Plain Layout + +(OA.+) -- ++(-2,0) to[american voltage source,l=$v_{in}$] ($(OA.+ |- OA.out)+(-2,-2 +)$) node(G)[ground]{} +\end_layout + +\begin_layout Plain Layout + +(OA.-) -- ++(0,-1) -- ($(OA.out |- OA.-)+(0,-1)$) -- (OA.out) -- ++(1,0) to[R=$R_L$] + ($(OA.out |- G) + (1,0)$) node[ground]{}; +\end_layout + +\begin_layout Plain Layout + + +\backslash +end{circuitikz} +\end_layout + +\begin_layout Plain Layout + + +\backslash +end{center} +\end_layout + +\end_inset + + +\end_layout + +\begin_layout Standard +Tenemos +\begin_inset Formula $v_{out}=v_{in}$ +\end_inset + + (por tanto +\begin_inset Formula $A_{V}=1$ +\end_inset + +). + Esto se usa principalmente como etapa de adaptación de la entrada al sistema, + proporcionando una elevada resistencia de entrada. +\end_layout + +\begin_layout Subsection +Sumador inversor +\end_layout + +\begin_layout Standard +\begin_inset ERT +status open + +\begin_layout Plain Layout + + +\backslash +begin{center} +\end_layout + +\begin_layout Plain Layout + + +\backslash +begin{circuitikz} +\end_layout + +\begin_layout Plain Layout + + +\backslash +draw (0,0) node(OA)[op amp]{} +\end_layout + +\begin_layout Plain Layout + +(OA.-) -- ++(-1,0) -- ++(0,1) to[R=$R_A$] ++(-4,0) to[american voltage source,l=$ +v_A$] ++(0,-4) node(G)[ground]{} +\end_layout + +\begin_layout Plain Layout + +($(OA.-)+(-1,0)$) -- ++(0,-1) to[R=$R_B$] ++(-2,0) to[american voltage source,l=$ +v_B$] ++(0,-2) node[ground]{} +\end_layout + +\begin_layout Plain Layout + +(OA.-) -- ++(0,1) to[R=$R_f$] ($(OA.out |- OA.-) + (0,1)$) -- (OA.out) -- ++(1,0) + to[R=$R_L$] ($(OA.out |- G) + (1,0)$) node[ground]{} +\end_layout + +\begin_layout Plain Layout + +(OA.+) to[R=$R_{bias}$] (OA.+ |- G) node[ground]{}; +\end_layout + +\begin_layout Plain Layout + + +\backslash +end{circuitikz} +\end_layout + +\begin_layout Plain Layout + + +\backslash +end{center} +\end_layout + +\end_inset + + +\end_layout + +\begin_layout Standard +Aquí, como +\begin_inset Formula $i_{-}=i_{+}=0$ +\end_inset + +, se tiene +\begin_inset Formula $v_{+}=R_{bias}i_{+}=0$ +\end_inset + +, y como hay realimentación negativa, +\begin_inset Formula $v_{-}=v_{+}=0$ +\end_inset + +. + Ahora bien, +\begin_inset Formula $\frac{v_{A}-v_{-}}{R_{A}}+\frac{v_{B}-v_{-}}{R_{B}}=\frac{v_{-}-v_{out}}{R_{f}}$ +\end_inset + +, y como +\begin_inset Formula $v_{-}=0$ +\end_inset + +, nos queda que +\begin_inset Formula $v_{out}=-R_{f}\left(\frac{v_{A}}{R_{A}}+\frac{v_{B}}{R_{B}}\right)$ +\end_inset + +. +\end_layout + +\begin_layout Subsection +Amplificador diferencial +\end_layout + +\begin_layout Standard +\begin_inset ERT +status open + +\begin_layout Plain Layout + + +\backslash +begin{center} +\end_layout + +\begin_layout Plain Layout + + +\backslash +begin{circuitikz} +\end_layout + +\begin_layout Plain Layout + + +\backslash +draw (0,0) node(OA)[op amp]{} +\end_layout + +\begin_layout Plain Layout + +(OA.-) to[R=$R_A$] ++(-4,0) to[american voltage source,l=$v_A$] ++(0,-3) + node(G)[ground]{} +\end_layout + +\begin_layout Plain Layout + +(OA.+) to[R=$R_B$] ++(-2,0) to[american voltage source,l=$v_B$] ($(OA.+ |- + G) + (-2,0)$) node[ground]{} +\end_layout + +\begin_layout Plain Layout + +(OA.+) to[R=$R_C$] (OA.+ |- G) node[ground]{} +\end_layout + +\begin_layout Plain Layout + +(OA.-) -- ++(0,1) to[R=$R_f$] ($(OA.out |- OA.-)+(0,1)$) -- (OA.out) -- ++(1,0) + to[R=$R_L$] ($(OA.out |- G)+(1,0)$) node[ground]{} +\end_layout + +\begin_layout Plain Layout + +(1,-2) node{$ +\backslash +frac{R_C}{R_B}= +\backslash +frac{R_f}{R_A}$}; +\end_layout + +\begin_layout Plain Layout + + +\backslash +end{circuitikz} +\end_layout + +\begin_layout Plain Layout + + +\backslash +end{center} +\end_layout + +\end_inset + + +\end_layout + +\begin_layout Standard +Como +\begin_inset Formula $i_{+}=0$ +\end_inset + +, toda la corriente que sale de +\begin_inset Formula $R_{B}$ +\end_inset + + va a +\begin_inset Formula $R_{C}$ +\end_inset + + y +\begin_inset Formula $v_{B}=i_{B}(R_{B}+R_{C})$ +\end_inset + +, y se tiene +\begin_inset Formula $v_{-}=v_{+}=i_{B}R_{C}=v_{B}\frac{R_{C}}{R_{B}+R_{C}}$ +\end_inset + +. + Ahora bien, como +\begin_inset Formula $i_{-}=0$ +\end_inset + +, nos queda +\begin_inset Formula $v_{-}=v_{A}-i_{A}R_{A}=i_{A}R_{f}+v_{out}$ +\end_inset + +, con lo que +\begin_inset Formula $i_{A}=\frac{v_{A}-v_{out}}{R_{A}+R_{f}}$ +\end_inset + +. + Sustituyendo e igualando, +\begin_inset Formula +\begin{multline*} +v_{B}\frac{R_{C}}{R_{B}+R_{C}}=\frac{v_{A}-v_{out}}{R_{A}+R_{f}}R_{f}+v_{out}=v_{A}\frac{R_{C}}{R_{B}+R_{C}}+v_{out}\frac{R_{B}}{R_{B}+R_{C}}\implies\\ +\implies v_{B}R_{C}-v_{A}R_{C}=v_{out}R_{B}\implies v_{out}=\frac{R_{C}}{R_{B}}(v_{B}-v_{A})=\frac{R_{f}}{R_{A}}(v_{B}-v_{A}) +\end{multline*} + +\end_inset + +Para minimizar los efectos de la corriente de polarización (?) se deben + seleccionar +\begin_inset Formula $R_{A}=R_{B}$ +\end_inset + + y +\begin_inset Formula $R_{C}=R_{f}$ +\end_inset + +. +\end_layout + +\begin_layout Subsection +Integrador +\end_layout + +\begin_layout Standard +\begin_inset ERT +status open + +\begin_layout Plain Layout + + +\backslash +begin{center} +\end_layout + +\begin_layout Plain Layout + + +\backslash +begin{circuitikz} +\end_layout + +\begin_layout Plain Layout + + +\backslash +draw (0,0) node(OA)[op amp]{} +\end_layout + +\begin_layout Plain Layout + +(OA.+) -- ++(0,-2) node(G)[ground]{} +\end_layout + +\begin_layout Plain Layout + +(OA.-) to[R=$R$] ++(-2,0) to[american voltage source,l=$v_{in}$] ($(OA.- |- + G)+(-2,0)$) -- (G) +\end_layout + +\begin_layout Plain Layout + +(OA.-) -- ($(OA.-)+(0,2.5)$) to[ospst,l=Reset] ($(OA.out |- OA.-)+(0,2.5)$) -- + (OA.out) +\end_layout + +\begin_layout Plain Layout + +($(OA.-)+(0,1)$) to[C=$C$] ($(OA.out |- OA.-)+(0,1)$) +\end_layout + +\begin_layout Plain Layout + +(OA.out) -- ++(1,0) to[R=$R_L$] ($(OA.out |- G)+(1,0)$) -- (G); +\end_layout + +\begin_layout Plain Layout + + +\backslash +end{circuitikz} +\end_layout + +\begin_layout Plain Layout + + +\backslash +end{center} +\end_layout + +\end_inset + + +\end_layout + +\begin_layout Standard +La tensión de salida es +\begin_inset Formula $v_{out}=-\frac{1}{RC}\int_{0}^{t}v_{in}$ +\end_inset + +. +\end_layout + +\begin_layout Subsection +Derivador +\end_layout + +\begin_layout Standard +\begin_inset ERT +status open + +\begin_layout Plain Layout + + +\backslash +begin{center} +\end_layout + +\begin_layout Plain Layout + + +\backslash +begin{circuitikz} +\end_layout + +\begin_layout Plain Layout + + +\backslash +draw (0,0) node(OA)[op amp]{} +\end_layout + +\begin_layout Plain Layout + +(OA.out) -- ++(1,0) to[R=$R_L$] ++(0,-2) node(H){} +\end_layout + +\begin_layout Plain Layout + +(OA.+) -- (OA.+ |- H) node(G)[ground]{} -- (H) +\end_layout + +\begin_layout Plain Layout + +(OA.-) -- ++(0,1) to[R=$R$] ($(OA.out |- OA.-)+(0,1)$) -- (OA.out) +\end_layout + +\begin_layout Plain Layout + +(OA.-) to[C=$C$] ++(-2,0) to[american voltage source,l=$v_{in}$] ($(OA.- |- + G)+(-2,0)$) -- (G); +\end_layout + +\begin_layout Plain Layout + + +\backslash +end{circuitikz} +\end_layout + +\begin_layout Plain Layout + + +\backslash +end{center} +\end_layout + +\end_inset + + +\end_layout + +\begin_layout Standard +La tensión de salida es +\begin_inset Formula $v_{out}=-RC\frac{dv_{in}}{dt}$ +\end_inset + +. +\end_layout + +\begin_layout Section +Conversión digital a analógica (DAC) +\end_layout + +\begin_layout Standard +Consiste en reconstruir una señal analógica a partir de una serie de muestras + en código binario. + La señal reconstruida no es la misma que la original, pues está retrasada + en el tiempo respecto a esta y los códigos no contienen información sobre + el valor de la señal entre dos muestras ni representan las amplitudes exactas + de estas. + La diferencia entre el valor de muestreo y la amplitud reconstruida se + denomina +\series bold +error +\series default + o +\series bold +ruido de cuantificación +\series default +. +\end_layout + +\begin_layout Standard +Una posible implementación de DAC es aquella basada en una red de resistencias + pon +\begin_inset ERT +status open + +\begin_layout Plain Layout + + +\backslash +- +\end_layout + +\end_inset + +de +\begin_inset ERT +status open + +\begin_layout Plain Layout + + +\backslash +- +\end_layout + +\end_inset + +ra +\begin_inset ERT +status open + +\begin_layout Plain Layout + + +\backslash +- +\end_layout + +\end_inset + +das y un amplificador operacional. +\end_layout + +\begin_layout Standard +\begin_inset ERT +status open + +\begin_layout Plain Layout + + +\backslash +begin{center} +\end_layout + +\begin_layout Plain Layout + + +\backslash +begin{circuitikz} +\end_layout + +\begin_layout Plain Layout + + +\backslash +newcommand*{ +\backslash +equal}{=} +\end_layout + +\begin_layout Plain Layout + + +\backslash +draw (0,3) node(sa)[spdt,rotate=-90]{} node[left]{$d_0$} (2,3) node(sb)[spdt,rot +ate=-90]{} node[left]{$d_1$} (4,3) node(sc)[spdt,rotate=-90]{} node[left]{$d_2$} + (7,3) node(sn)[spdt,rotate=-90]{} node[left]{$d_{n-1}$} (9,1) node(oa)[op + amp]{} +\end_layout + +\begin_layout Plain Layout + +(sa.out 1) node[ground]{} (sb.out 1) node[ground]{} (sc.out 1) node[ground]{} + (sn.out 1) node[ground]{} +\end_layout + +\begin_layout Plain Layout + +(sa.in) to[R=$R$] ++(0,2) (sb.in) to[R=$2R$] ++(0,2) (sc.in) to[R=$4R$] ++(0,2) + (sn.in) to[R=$ +\backslash +cdots +\backslash + +\backslash + +\backslash + 2^{n-1}R$] ++(0,2) +\end_layout + +\begin_layout Plain Layout + +%($0.5*(sc.in)+0.5*(sn.in)+(0,1)$) node{$ +\backslash +cdots$} +\end_layout + +\begin_layout Plain Layout + +($0.5*(sa.in)+0.5*(sn.in)+(0,2)$) -- ++(0,1) node[right]{$V_{ref}$} +\end_layout + +\begin_layout Plain Layout + +($(sa.in)+(0,2)$) -- ++(7,0) +\end_layout + +\begin_layout Plain Layout + +(sa.out 2) -- (sa.out 2 |- oa.-) -- (oa.-) (sb.out 2) -- (sb.out 2 |- oa.-) (sc.out + 2) -- (sc.out 2 |- oa.-) (sn.out 2) -- (sn.out 2 |- oa.-) +\end_layout + +\begin_layout Plain Layout + +(oa.-) -- ++(0,1) to[R=$R_f +\backslash +equal +\backslash +frac R2$] ($(oa.out |- oa.-)+(0,1)$) -- (oa.out) -- ++(1,0) to[R=$R_L$] ++(0,-2) + node(G)[ground]{} +\end_layout + +\begin_layout Plain Layout + +(oa.+) -- (oa.+ |- G) node[ground]{}; +\end_layout + +\begin_layout Plain Layout + + +\backslash +end{circuitikz} +\end_layout + +\begin_layout Plain Layout + + +\backslash +end{center} +\end_layout + +\end_inset + + +\end_layout + +\end_body +\end_document |
