5. Differential Amplifiers

Transcription

1 5. iffeential plifies eain: Sea & Sith: Chapte 8 MOS ptins an Chapte.. ECE, Winte, F. Najabai

2 iffeential an Cn-Me Sinals Cnsie a linea iuit with TWO inputs By supepsitin: efine: iffeene iffeential Me Cn Me Substitutin f an in the expessin f : ut

3 iffeential an Cn-Me Sinals linea iuit with TWO inputs iffeential Gain: Cn Me Gain: Cn Me ejetin ati CM*: / The espnse f the iuit t tw inepenent sinal is a supepsitin f espnse t the iffeential an n e sinals. i.e., f finin, we an alulate/easue eithe an pai an pai bth pais ae inepenent f alues f an * CM is usually ien in B: CMB l /

4 iffeential an Cn-Me Sinals F finin, we an alulate/easue eithe an pai an pai bth pais ae inepenent f alues f an Supepsitin finin an :. Set, pute f. Set, pute f. F any an : iffeene Meth finin an :. Set set / an / pute f. Set set an pute f. F any an :

5 ppliatin f iffeential & Cn-Me Nise upt sinals n bth wies alst equally if aeful, e.., twiste pais eula aplifie aplifies bth sinal an nise. iffeene aplifie with a lae CM aplifies the sinal substantially e than the nise ipes sinal t nise ati si nise si CM nise

6 iffeene plifie Iential Tansists F nw, we keep tak f tw utput, an, beause thee ae seeal ways t nfiue ne utput f this iuit.

7 Cautin In Chapte.., Sea & Sith efine But in Chapte 8, Sea & Sith uses While keepin this is innsistent Hee we use thuhut Theefe, letue ntes Sea & Sith f iffeene plifies. Use etue Slies Ntatin!

8 iffeene plifie Bias I I Sine V V V V G G an S S V I V GS S V V I GS V S I V GS S Een if Channelwith ulatin is inlue I I I GS-KV: V I GS SS V SS S-KV: V I V I S SS I GS Vtn k n V λv S Sle abe thee equatins t fin I, V GS,an V S.

9 iffeene plifie Sall Sinal

10 iffeene plifie Sall Sinal SS Ne Vltae Meth: Ne : Ne : Ne : be thee equatins shul be sle t fin, an Usin Supepsitin t fin an still leas t equatins in unknwn f eah ase! s s

11 iffeene plifie Set set an pute f s s Beause f suey an i i i We an sle f by ne ltae eth but thee is a siple an e eleant way

12 iffeene plifie Set set an pute f Beause f suey an i i i i i i i i

13 iffeene plifie Set set an pute f Beause f suey an i i i i i i i i

14 Beause f suey iffeene plifie Set set an pute f an i i i i i CS plifie with s SS / i i SS /

15 iffeene plifie Set set / an / pute f.5.5 s s SS Ne Vltae Meth: Ne : Ne : Ne :

16 iffeene plifie Ne Ne : Ne : SS SS Ne : Ne : Ne : Only pssible slutin:

17 iffeene plifie Set set / an / pute f i i i i i i i i i CS plifie i i.5.5

18 Cnept f Half Ciuit Cn Me iffeential Me

19 Cnept f Half Ciuit : Cn Me Cn Me iuit i i s s i i Cn Me Half-iuit. Cuents abut syety line ae equal.. Vltaes abut the syety line ae equal e..,. N uent sses the syety line.

20 Cnept f Half Ciuit : iffeential Me iffeential Me iuit i i i i s s iffeential Me Half-iuit. Cuents abut the syety line ae equal in alue an ppsite in sin.. Vltaes abut the syety line ae equal in alue an ppsite in sin.. Vltae at the suey line is ze

21 Cnstutin Half Ciuits Step :. iie eleents that ss the syety line e.., an/ ae late n the syety line uent sue suh that we hae a syeti iuit nly wies shul ss the syety line, nthin shul be late n the syety line!

22 Cnstutin Half Ciuit Cn Me Step : Cn Me Half-iuit. Cuents abut syety line ae equal e.., i i.. Vltaes abut the syety line ae equal e..,.. N uent sses the syety line.

23 Cnstutin Half Ciuit iffeential Me Step : iffeential Me Half-Ciuit. Cuents abut syety line ae equal but ppsite sin e.., i i. Vltaes abut the syety line ae equal but ppsite sin e..,. Vltae n the syety line is ze. i i.5.5

24 Half-Ciuit wks nly if the iuit is syeti! We an still use half iuit if the eiatin f pefet syety is sall i.e., if ne tansist has an the the with <<. Half iuits f n-e an iffeential e ae iffeent. Bias iuit is siila t Half iuit f n e Nt all iffeene aplifies ae syeti. k at the la aefully!

25 Output Cnfiuatins f iffeential plifies iffeential Output Sinle-ene Output Tw Sepaate Outputs i.e., input t anthe iffeene aplifie is ine in the fllwin analysis T inlue, siply eplae with

26 iffeential plifies with iffeential Output iffeential Me iffeential Output Cn Me

27 iffeential plifies with iffeential Output iffeential Output iffeential Me Cn Me / / /.5 /.5 /.5 / / / SS CM

28 iffeential plifies with Sinle-ene Output iffeential Me Sinle-ene Output Cn Me T use half iuit, Shul be lae s that syety is pesee i.e.

29 iffeential plifies with Sinle-ene Output Sinle-ene Output iffeential Me Cn Me SS / T use half iuit, Shul be lae s that syety is pesee i.e. CM SS /

30 iffeential plifies with Tw Outputs Tw Sepaate Outputs i.e., input t anthe iffeene aplifie iffeential Me Cn Me T use half iuit, Shul be lae s that syety is pesee i.e.

31 iffeential plifies with Tw Outputs SS / iffeential Me Cn Me epsin utput int iffeential an n-e: SS /.5

32 iffeential plifies with Tw Outputs epsin utput int iffeential an n-e:.5 SS / efine the equialent f SS f tw utputs / SS / plifie iffeential pnent f the sinal uh lae than n e f the sinal N ss-uplin between iffeential an n e f the sinals