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- Differential Amplifier - This figure shows the schematic diagram of differential amplifier. By varing Rin, one can control the input current of MN1 and MN2. The gain of this circuit depends on input current and demension of MN1 and MN2 transistors. From the hand calculation, gain is proportional with sqrt(W1/L1) and sqrt(1/I1). Two models, orbit model and cherry model, are used to compare their properties. |
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- Typical DC characteristic of differential amplifier - |
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- Differntial mode gain vs. Input Current -
-- log scale -- i) option scale = 0.6um ii) W1/L1=W2/L2=W3/L3=W4/L4=100/8, W5/L5=200/8, W6/L6=100/4 iii) I1 and I2 are changed with various R values iV) Adiff_orbit was constant through various current range(???) V) Adiff_cherry decreases with input current. BUT not linear!!!!! |
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- Differntial mode gain vs. W1 and W2 -
-- log scale -- i) option scale = 0.6um ii) L1=L2=8 W3/L3=W4/L4=100/8, W5/L5=200/8, W6/L6=100/4, R=40Kohm, I1=39uA(orbit), 35uA(cherry) iii) Both gains increase with W1. iv) Adiff_orbit => not linear. v) Adiff_cherry => very linear. |
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- Differntial mode gain vs. L1 and L2 -
-- log scale -- i) option scale = 0.6um ii) W1=W2=100 W3/L3=W4/L4=100/8, W5/L5=200/8, W6/L6=100/4, R=40Kohm, I1=39uA(orbit), 35uA(cherry) iii) Both gains are linear at high L1. |