EECS 105 Spring 2002 Lecture 36 Output Voltage Swing R T Howe EECS 105 Spring 2002 Lecture 36 R T Howe Limits to Output Voltage M6 will leave saturation when vOUT drops to vOUT MIN V VDS 6 sat 2 5 2I D6 nCox W L 6 vOUT MIN 2 5 0 28 2 22 V M2 will leave saturation when vOUT rises to vOUT MAX V VSD 2 sat 2 5 vOUT MAX 2 5 0 32 2 18 V Transistors M2 and M6 will limit the output swing What about M4 University of California at Berkeley Dept of EECS EECS 105 Spring 2002 Lecture 36 R T Howe EECS 105 Spring 2002 Lecture 36 iOUT MAX iD 6 0 50 A vOUT MIN RL Output current iOUT vOUT RL iOUT iD 6 iD 2 Limits asymmetrical M2 can increase iD2 M6 can t increase iD6 Dept of EECS R T Howe Output Current Limits Positive output current negative vOUT Load resistor pick RL 25 k vOUT University of California at Berkeley Dept of EECS Output Current Swing iOUT 2 I D 2 p Cox W L 2 University of California at Berkeley vOUT MIN 50 A 25k 1 25V less negative than limit set by saturation of M6 Negative output current positive vOUT No limit on current from M2 so voltage swing sets current limit iOUT MIN vOUT MAX RL 2 18V 25k 87 2 A Dept of EECS University of California at Berkeley 1 EECS 105 Spring 2002 Lecture 36 R T Howe Transfer Curves for RL 25 k Loaded voltage gain vout vin gm1Rout1 gm2Rout RL 490 Loaded transconductance iout vin gm1Rout1 gm2 Rout Rout RL 19 5 mS 2 1 vOUT iOUT A 2 100 1 50 1 0 1 2 Dept of EECS 2 vIN 2 1 0 1 50 2 vIN 100 University of California at Berkeley 2
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