hw1_sol_04-02-05-09-32

hw1_sol_04-02-05-09-32 - EE240 HW#1 Solution Spring 2003

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Id vs V* or vs for a 10/1um pmos device Id 314.159 µ A = Id gm V star 2 := Calculate Id gm 3.142mS = gm wu C L := Calculate gm required for a unity gain frequency of 50MHz gm Id 2 V star = 10V 1 = note V star 200mV := L1 µ m := C L 10pF := wu 2 π 50 MHz := Problem 1 Reference:C:\Users\Bernhard\Lib\MathCAD\Default\defaults.mcd EE240 HW#1 Solution Spring 2003
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Since CL=10pF is so large in this example, we can neglect transistor self-loading and incur only a small error. But of course that's not always the case. Vin Vdd Cdtot Cload I bias M1 Verify bandwidth Simulate one more time: With 353um we get Id = 315uA which is good enough. Try W = 353 um. 321 µ A Id 1 W 352.597 µ m = Lets go back to spice to check this (use same spice file above): We get 321uA for a 360um device so reduce W a bit. W 360.274 µ m = W1 0 µ m Id 8.72 µ A := and solving for W we have: Id W 1 µ m 10 µ m 1 µ m I 10um = Id 314.159 µ A = and the current desired current is: I 10um 8.72 µ A = So we can calculate the expected width for the device by noting that the current through the 10um/1um pmos device is: $ Problem 1: Size pmos device by plotting Id versus V* = 2*Id/gm mn dn dn 0 0 pmos L=1um W=10um vdn 0 dn dc 1V .dc vdn 10mV 3V 10mV * Note that vs is V*. .. .probe vs = par('-2*i(mn)/gmo(mn)') .probe Id = par('-i(mn)') .options dccap post=2 brief .lib 'cmos35.txt' nominal .end SPICE code used to generate the above graph:
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Gain in dB Vs Frequency, Note avo = -281
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This note was uploaded on 08/01/2008 for the course EECS 240 taught by Professor Boser during the Spring '04 term at Berkeley.

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hw1_sol_04-02-05-09-32 - EE240 HW#1 Solution Spring 2003

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