解: =0.025mSG,==0.0lmSG =0.04mS R R R G I=2.5mA G1+G2+G3 Rs I G I。=10mA R G1+G2+G3 G I。=4mA G1+G,+G2解： 0.025mS R 1 G 1 1 = = 0.01mS R 1 G 2 2 = = 0.04mS R 1 G 3 3 = = I 2.5mA G G G G I S 1 2 3 1 1 = + + = I 10mA G G G G I S 1 2 3 2 2 = + + = I 4mA G G G G I S 1 2 3 3 3 = + + =