Two Port Characterizations

Transcription

1 lectronc Crcuts Two Port Characterzatons Contents Input and output resstances Two port networks Models Prof. C.K. Tse: -port networks

2 Impedances and loadng effects Voltage amplfers R s R out smaller the better (the best s 0) s n R n A n o R LOAD larger the better (the best s ) Prof. C.K. Tse: -port networks

3 Impedances and loadng effects Current amplfers n larger the better (the best s ) A n s R s R n R out out R LOAD smaller the better (the best s 0) Prof. C.K. Tse: -port networks 3

4 Impedances and loadng effects Transconductance amplfers R s larger the better (the best s ) s n R n G m n R out out R LOAD larger the better (the best s ) Prof. C.K. Tse: -port networks 4

5 Impedances and loadng effects Transresstance amplfers n R out smaller the better (the best s 0) s R s R n R m n o R LOAD smaller the better (the best s 0) Prof. C.K. Tse: -port networks 5

6 Fndng mpedances Input mpedance Inject a current to the nput, fnd the oltage. The rato of the oltage to current ges the nput resstance. x x R n WITH Output open-crcut f t s supposed to be a oltage output (e.g., oltage amplfers and transresstance amplfers) short-crcut f t s supposed to be a current output (current amplfers and transconductance amplfers) Prof. C.K. Tse: -port networks 6

7 Fndng mpedances Output mpedance Inject a current at output, fnd the oltage. The rato of the oltage to current ges the output resstance. WITH nput short-crcut f t s supposed to be a oltage nput (e.g., oltage amplfers and transconductance amplfers) x x open-crcut f t s supposed to be a current nput (current amplfers and transresstance amplfers) Prof. C.K. Tse: -port networks R out 7

8 xample: C amplfer wth D Input resstance s B B C r n B n n B B r r π o r ~ o n B g m B B B R B R B r π R B r π /( β) r ( β) R π Prof. C.K. Tse: -port networks 8

9 xample: F amplfer B r π R ~ g m B C r o r out m m Output resstance s r out m B B g R R m gm r g m g β π g m m m B m B g R r R g π m m Prof. C.K. Tse: -port networks 9

10 Quck rule r π ( β) R R Prof. C.K. Tse: -port networks 0

11 xample r ( β)[ R ( r ( β) R )] π π R R Prof. C.K. Tse: -port networks

12 Quck rule R B R B g m R B β R g m R B β R Prof. C.K. Tse: -port networks

13 xample R L R B R g m R L R β B R Prof. C.K. Tse: -port networks 3

14 General two port characterzatons Prof. C.K. Tse: -port networks 4

15 Types of characterzatons Immttance parameters - z-parameters - y-parameters Hybrd parameters - h-parameters - g-parameters Prof. C.K. Tse: -port networks 5

16 z-parameters z z z z z z z z 0 (open-crcut port ) 0 (open-crcut port ) 0 (open-crcut port ) 0 (open-crcut port ) Prof. C.K. Tse: -port networks 6

17 y-parameters y y y y y y y y 0 (short-crcut port ) 0 (short-crcut port ) 0 (short-crcut port ) 0 (short-crcut port ) Prof. C.K. Tse: -port networks 7

18 h-parameters BJT model n some books: h r π nput resstance h h fe β h /r o arly resstance h h h h h h h h 0 (short-crcut port ) 0 (open-crcut port ) 0 (short-crcut port ) 0 (open-crcut port ) Prof. C.K. Tse: -port networks 8

19 g-parameters g g g g g g g g 0 (open-crcut port ) 0 (short-crcut port ) 0 (open-crcut port ) 0 (short-crcut port ) Prof. C.K. Tse: -port networks 9

20 xample R R h h h h R R 0 R R R 0 R R R 0 R R 0 R RR R Prof. C.K. Tse: -port networks 0

21 Connectng two-ports seres-seres Z Z 4 Total [Z] T [Z][Z ] Prof. C.K. Tse: -port networks

22 Connectng two-ports shunt-shunt Y Y 4 Total [Y] T [Y] [Y ] Prof. C.K. Tse: -port networks

23 Connectng two-ports shunt-seres G G 4 Total [G] T [G] [G ] Prof. C.K. Tse: -port networks 3

24 Connectng two-ports seres-shunt H H 4 Total [H] T [H] [H ] Prof. C.K. Tse: -port networks 4

25 Crcut models We can deelop crcut model for each type of two-port descrptons. xample: h-parameter h h h h h h h h h h h /h Prof. C.K. Tse: -port networks 5

26 xample: BJT model We can model the BJT as a h-parameter model: h r π nput resstance h 0 h h fe β h /r o arly resstance r π β g m r o Prof. C.K. Tse: -port networks 6