\coordinate (origin) at (0,0);
\node[nmos,xscale=-1] (mr) at (-2,0) {};
\node[nmos]           (m1) at ( 2,0) {};

\draw (mr.gate) -- (origin) -- (m1.gate);

\draw (m1.gate) to [short,*-] (m1.gate|-m1.drain) 
               to [short,-*] (m1.drain);

\draw (mr.drain) to   [short,-] ++ (0,0.25)
                node [nmos,anchor=source,xscale=-1] (mx) {}; 

\draw (mx.gate) to [short,*-] (mx.gate|-mx.drain) 
               to [short,-*] (mx.drain);

\draw (mx.drain) to [short,-o,f<_=$I_{\mathrm{R}}$] ++ (0,1.25) coordinate (in); 

\draw (mr.source) to [short,-] ++ (0,-0.3) coordinate (x) 
                 to [short,-*] (x-|origin) coordinate (gnd)
                 to [short,-] (gnd-|m1.source) 
                 to [short,-] (m1.source);

\draw (m1.drain) to [short,-] (m1.drain|-mx.source)
                node [nmos,anchor=source] (m2) {}; 
\draw (mx.gate) -- (m2.gate);

\draw (m2.drain) to [short,-o,f<=$I_{\mathrm{O}}$] (m2.drain|-in) coordinate (out);  

\node[vss] at (gnd) {};

\path [voltarrow] ($(in)+(-1,0)$) edge[bend left=-30] 
 node[midway,left,inner sep=1pt] 
 {$V_{\mathrm{R}}$} ($(mr.source)+(-1,0)$);

\path [voltarrow] (mr.gate) edge[bend right=-30] 
 node[midway,below right,inner sep=1pt] 
 {$V_{\mathrm{GS}}$} (mr.source);
\path [voltarrow] (m1.gate) edge[bend left=-30] 
 node[midway,below left,inner sep=1pt] 
 {$V_{\mathrm{GS}}$} (m1.source);
\path [voltarrow] ($(out)+(1,0)$) edge[bend right=-30] 
 node[midway,right,inner sep=1pt] 
 {$V_{\mathrm{O}}$} ($(m1.source)+(1,0)$);


\node[ anchor    = east
    , inner sep = 2pt
    , font      = \footnotesize
    ] () at ($(mr.source)!0.775!(mr.drain)$) {MNCM1A};
\node[ anchor    = east
    , inner sep = 2pt
    , font      = \footnotesize
    ] () at ($(mx.source)!0.775!(mx.drain)$) {MNCM2R};
\node[ anchor    = west
    , inner sep = 2pt
    , font      = \footnotesize
    ] () at ($(m1.source)!0.775!(m1.drain)$) {MNCM1R};
\node[ anchor    = west
    , inner sep = 2pt
    , font      = \footnotesize
    ] () at ($(m2.source)!0.775!(m2.drain)$) {MNCM2A};