差動増幅回路の解析

以下の回路を解析したい（利得Vo/Viを求めたい）

等価回路は以下だと考えられる

(%i4) A : matrix([-R0,0,0,1],[0,-R2,0,-1],[0,0,-R1,1],[1,-1,1,0]);
                           [ - R0   0     0     1  ]
                           [                       ]
                           [  0    - R2   0    - 1 ]
(%o4)                      [                       ]
                           [  0     0    - R1   1  ]
                           [                       ]
                           [  1    - 1    1     0  ]

逆行列

invert(A);
(%i7) invert(A);
               [          R2 + R1           ]
               [  ------------------------  ]
               [  (- R0 (R2 + R1)) - R1 R2  ]
               [                            ]
               [             R1             ]
               [  ------------------------  ]
               [  (- R0 (R2 + R1)) - R1 R2  ]
(%o7)  Col 1 = [                            ]
               [              R2            ]
               [ - ------------------------ ]
               [   (- R0 (R2 + R1)) - R1 R2 ]
               [                            ]
               [            R1 R2           ]
               [ - ------------------------ ]
               [   (- R0 (R2 + R1)) - R1 R2 ]
         [            R1            ]         [              R2            ]
         [ ------------------------ ]         [ - ------------------------ ]
         [ (- R0 (R2 + R1)) - R1 R2 ]         [   (- R0 (R2 + R1)) - R1 R2 ]
         [                          ]         [                            ]
         [         R1 + R0          ]         [             R0             ]
         [ ------------------------ ]         [  ------------------------  ]
         [ (- R0 (R2 + R1)) - R1 R2 ]         [  (- R0 (R2 + R1)) - R1 R2  ]
 Col 2 = [                          ] Col 3 = [                            ]
         [            R0            ]         [          R2 + R0           ]
         [ ------------------------ ]         [  ------------------------  ]
         [ (- R0 (R2 + R1)) - R1 R2 ]         [  (- R0 (R2 + R1)) - R1 R2  ]
         [                          ]         [                            ]
         [          R0 R1           ]         [            R0 R2           ]
         [ ------------------------ ]         [ - ------------------------ ]
         [ (- R0 (R2 + R1)) - R1 R2 ]         [   (- R0 (R2 + R1)) - R1 R2 ]
         [            R1 R2           ]
         [ - ------------------------ ]
         [   (- R0 (R2 + R1)) - R1 R2 ]
         [                            ]
         [           R0 R1            ]
         [  ------------------------  ]
         [  (- R0 (R2 + R1)) - R1 R2  ]
 Col 4 = [                            ]
         [            R0 R2           ]
         [ - ------------------------ ]
         [   (- R0 (R2 + R1)) - R1 R2 ]
         [                            ]
         [           R0 R1 R2         ]
         [ - ------------------------ ]
         [   (- R0 (R2 + R1)) - R1 R2 ]


[          R2 + R1           ]	[            R1            ] [              R2            ]	[            R1 R2           ]
[  ------------------------  ]	[ ------------------------ ] [ - ------------------------ ]	[ - ------------------------ ]
[  (- R0 (R2 + R1)) - R1 R2  ]	[ (- R0 (R2 + R1)) - R1 R2 ] [   (- R0 (R2 + R1)) - R1 R2 ]	[   (- R0 (R2 + R1)) - R1 R2 ]
[                            ]	[                          ] [                            ]	[                            ]
[             R1             ]	[         R1 + R0          ] [             R0             ]	[           R0 R1            ]
[  ------------------------  ]	[ ------------------------ ] [  ------------------------  ]	[  ------------------------  ]
[  (- R0 (R2 + R1)) - R1 R2  ]	[ (- R0 (R2 + R1)) - R1 R2 ] [  (- R0 (R2 + R1)) - R1 R2  ]	[  (- R0 (R2 + R1)) - R1 R2  ]
[                            ]	[                          ] [                            ]	[                            ]
[              R2            ]	[            R0            ] [          R2 + R0           ]	[            R0 R2           ]
[ - ------------------------ ]	[ ------------------------ ] [  ------------------------  ]	[ - ------------------------ ]
[   (- R0 (R2 + R1)) - R1 R2 ]	[ (- R0 (R2 + R1)) - R1 R2 ] [  (- R0 (R2 + R1)) - R1 R2  ]	[   (- R0 (R2 + R1)) - R1 R2 ]
[                            ]	[                          ] [                            ]	[                            ]
[            R1 R2           ]	[          R0 R1           ] [            R0 R2           ]	[           R0 R1 R2         ]
[ - ------------------------ ]	[ ------------------------ ] [ - ------------------------ ]	[ - ------------------------ ]
[   (- R0 (R2 + R1)) - R1 R2 ]	[ (- R0 (R2 + R1)) - R1 R2 ] [   (- R0 (R2 + R1)) - R1 R2 ]	[   (- R0 (R2 + R1)) - R1 R2 ]

LTSpiceIVでやってみた

Vin=5.0VでVout=3.85Vとかになって、増幅されずに減衰している？