Lecture 18. ANNOUNCEMENTS HW#10 will be posted tonight OUTLINE. Basic MOSFET amplifier MOSFET biasingi MOSFET current sources Common source amplifier

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1 Lectue 8 ANNOUNCEMENT HW#0 will be posted toniht OUTLINE Basic MOFET aplifie MOFET biasini MOFET cuent souces Coon souce aplifie eadin: Chapte EE05 Fall 007 Lectue 8, lide Pof. Liu, UC Bekeley

2 Basic MOFET Aplifie Fo lae sall sinal ain, the MOFET should be opeated in the satuation eion. V out should not fall below V in by oe than V TH. EE05 Fall 007 Lectue 8, lide Pof. Liu, UC Bekeley

3 MOFET Biasin The oltae at node is deteined by V,, and : Also, V V I G V V I µ n C ox W L ( V V ) G TH V VG whee V ( V VTH ) V V VTH µ C n ox W L EE05 Fall 007 Lectue 8, lide 3 Pof. Liu, UC Bekeley

4 elf Biased MOFET tae Note that thee is no oltae dopped acoss G M is opeatin in the satuation eion. I V I V G EE05 Fall 007 Lectue 8, lide 4 Pof. Liu, UC Bekeley

5 MOFETs as Cuent ouces A MOFET behaes as a cuent souce when it is opeatin in the satuation eion. An NMOFET daws cuent fo a point to ound ( sinks cuent ), wheeas a PMOFET daws cuent fo V to a point ( souces cuent ) ). EE05 Fall 007 Lectue 8, lide 5 Pof. Liu, UC Bekeley

6 Coon ouce tae: λ 0 Aplifie cicuit all-sinal analysis cicuit fo deteinin oltae ain, A A µ C in out n ox W L I all-sinal analysis cicuit fo deteinin output esistance, out EE05 Fall 007 Lectue 8, lide 6 Pof. Liu, UC Bekeley

7 Coon ouce tae: λ 0 Channel lenth odulation esults in educed sall sinal oltae ain and aplifie output esistance. all-sinal analysis cicuit fo deteinin oltae ain, A all-sinal analysis cicuit fo deteinin output esistance, out A in ( ) out O O EE05 Fall 007 Lectue 8, lide 7 Pof. Liu, UC Bekeley

8 C Gain Vaiation with L An ideal cuent souce has infinite sall sinal esistance. The laest A is achieed with a cuent souce as the load. ince λ is inesely popotional to L, A inceases with L. A o µ C n ox λi W L I µ n C I WL EE05 Fall 007 Lectue 8, lide 8 Pof. Liu, UC Bekeley ox

9 C tae with Cuent ouce Load ecall that a PMOFET can be used as a cuent souce fo V. Use a PMOFET as a load of an NMOFET C aplifie. A out ( ) O O O O EE05 Fall 007 Lectue 8, lide 9 Pof. Liu, UC Bekeley

10 PMO C tae with NMO Load An NMOFET can be used as the load fo a PMOFET C aplifie. A out ( O O ) O O EE05 Fall 007 Lectue 8, lide 0 Pof. Liu, UC Bekeley

11 C tae with iode Connected Load Aplifie cicuit all-sinal analysis cicuit includin MOFET output esistances λ 0: If λ 0: A ( W/ L ) A ( W/L) out O A is lowe, but tit is less dependent d on pocess paaetes (µ n and C ox and dain cuent (I ). O EE05 Fall 007 Lectue 8, lide Pof. Liu, UC Bekeley O O

12 C tae with iode Connected PMO Load λ 0: A out o o o o EE05 Fall 007 Lectue 8, lide Pof. Liu, UC Bekeley

13 C tae with eeneation Aplifie cicuit all-sinal analysis cicuit fo deteinin oltae ain, A If λ 0 : A EE05 Fall 007 Lectue 8, lide 3 Pof. Liu, UC Bekeley

14 Exaple A diode connected deice deeneates a C stae. A EE05 Fall 007 Lectue 8, lide 4 Pof. Liu, UC Bekeley

15 out of C tae with eeneation eeneation boosts the output ipedance: all-sinal analysis cicuit fo deteinin output esistance, out Cuent flowin down thouh is Cuent flowin down thouh o is ( ) i i i i i i ( ) ( ) O i i i EE05 Fall 007 Lectue 8, lide 5 Pof. Liu, UC Bekeley ( ) O O O i

16 Output Ipedance Exaples out O out O O O EE05 Fall 007 Lectue 8, lide 6 Pof. Liu, UC Bekeley

17 C tae with Gate esistance Fo low sinal fequencies, the ate conducts no cuent. Gate esistance does not affect the ain o I/O ipedances. EE05 Fall 007 Lectue 8, lide 7 Pof. Liu, UC Bekeley

18 C Coe with Biasin A G A G EE05 Fall 007 Lectue 8, lide 8 Pof. Liu, UC Bekeley