Lectue Feedback mple ntductn w Pt Netwk Negatve Feedback Un lateal Case Feedback plg nalss eedback applcatns Clse Lp Gan nput/output esstances e:83h 3 Feedback
w-pt Netwk z-paametes Open-Ccut mpedance z z z z z z z z t pt t pt Open-ccut nput mpedance z Open-ccut wad tansmpedance z Open-ccut evese Open-ccut z z tansmpedance utput mpedance e:83h 3 Feedback
w-pt Netwk -paametes Sht-Ccut dmttance t pt t pt Sht-ccut nput admttance Sht-ccut wad tansadmttance Sht-ccut evese Sht-ccut tansadmttance utput admttance e:83h 3 Feedback 3
w-pt Netwk h-paametes hbd h h h h h h h h t pt t pt Sht-ccut nput mpedance h Sht-ccut wad cuent gan h Open-ccut evese Open-ccut h h vltage gan utput admttance e:83h 3 Feedback 4
w-pt Netwk g-paametes nvese-hbd g g g g g g g g t pt t pt Open-ccut nput admttance g Open-ccut wad cuent gan g Sht-ccut evese Sht-ccut g g cuent gan utput mpedance e:83h 3 Feedback 5
z-paamete example e:83h 3 Feedback 6 [ ] Ω Ω Ω Ω 3 3 Z Z Z Z Z [ ] Ω Ω Ω Ω 6 6 6 6 6 6 6 6 Z Z Z Z Z [ ] Ω Ω Ω Ω 9 6 6 8 6 6 6 6 9 8 Z Z Z Z Z Nte: z-matx n the last ccut sum tw me z-matces z-paametes s nmall used n analss sees-sees ccuts 3 Z Z ecpcal ccut 4 Z Z and Z Z smmetcal and ecpcal ccut
-paamete example.5s.5.5.5s.5.5.5 [ ].5.5S.5S..5.8.65.65S.69.65.65 [ ] e:83h 3 Feedback 7 But....5..5 B ecpcal,.769.769.69s.769s.65s
-paamete example Cnt..5.69.9.5.769.69.5S.S.69.5.69. S.769.65..5.65.5.5.5S.5.9.5.5.769.5 [ Y ].69 Nte: the -matx s equal t the sum tw me nes. heee, -paametes s nmall used n analss shunt-shunt ccuts What cnnectn shuld be h- g- paametes? e:83h 3 Feedback 8
Geneal Feedback Stuctue e:83h 3 Feedback 9 : Open Lp Gan / : eedback act / S s Nte : eedback : munt Lp Gan : Clse lp gan : CL s CL
Negatve Feedback Ppetes Negatve eedback takes a sample the utput sgnal and apples t t the nput t get seveal desable ppetes. n amples, negatve eedback can be appled t get the llwng ppetes Desenstzed gan : gan less senstve t ccut cmpnent vaatns educe nnlnea dsttn : utput pptnal t nput cnstant gan ndependent sgnal level educe eect nse Cntl nput and utput mpedances b applng apppate eedback tplges xtend bandwdth ample ll these ppetes can be acheved b tadng gan e:83h 3 Feedback
Gan De-senstvt Feedback can be used t desenstze the clsed lp gan t vaatns n the basc amplle. ssume s cnstant. ake deentals the clsed lp gan equatn gves, CL Deental espected wth CL d CL Dvded b v, the clse lp gan senstvt s equal t, d d d d CL CL d d hs esult shws the eects vaatns n n CL s mtgated b the eedback amunt. s als called the desenstvt amunt. e:83h 3 Feedback
Basc Feedback plges Dependng n the nput sgnal vltage cuent t be ampled and m the utput vltage cuent, amples can be classed nt u categes. Dependng n the ample categ, ne u tpes eedback stuctues shuld be used. pe Feedback pe Sensng Sees ltage Shunt ltage Sees ltage Sees Cuent 3 Shunt Cuent Shunt ltage 4 Shunt Cuent Sees Cuent e:83h 3 Feedback
Feedback Stuctue Sees Shunt e:83h 3 Feedback 3 ltage ample vltage-cntlled vltage suce eques hgh nput mpedance, lw utput mpedance ltage-vltage eedback ltage Gan Calculatn: we get nd, whee Clse Lp ltage Gan CL
nput/output esstance Sees Shunt e:83h 3 Feedback 4 nput esstance: n n Output esstance Clsed lp utput esstance wth ze nput vltage ut ut
h-paamete Mdelng Onl un-lateal case wll be cnsdeed : NO evese dependent sgnal und n the ample netwk. h a NO evese dependent sgnal und n the eedback netwk. h e:83h 3 Feedback 5
Un-lateal Fm nput pt : Fm utput pt : h Put F CL h whee z h h a a h h e:83h 3 Feedback 6 a a h Wth the eedback h a h Z h a h Y s L h a z h a h z h s Y, the Open Lp Gan, h h Z h and L a a Z z s h h h a h h h a h a a Y L h back t st equatn, Y, the Clsed Lp Gan s h z L a
Sees-Shunt xample 5 Gven :, kω, 9kΩ, MΩ and 4Ω t s bseved that: Sees cnnectn n nput pts Shunt cnnectn n utput pts Sees-Shunt cnnectn h-paamete shuld be used. quvalent ccut e:83h 3 Feedback 7
h-paamete analss e:83h 3 Feedback 8 k h h h..9 //
Fstl,set h m the nput pt, ~ h m utput pt, b puttng heee, the pen lp vltage gan s 5 OP ~ nd the clse lp vltage gan, CL h OP OP pen lp ccut and and h 5 5. ~, we get he nput mpedance, h e:83h 3 Feedback 9 n OP he utput mpedance, ut /// h OP
Feedback Stuctue Sees Sees e:83h 3 Feedback we get nd, whee Clse Lp ansadmttance Gan Gan Calculatn : CL
nput/output esstance Sees Sees e:83h 3 Feedback nput esstance: n Output esstance Clsed lp utput esstance wth ze nput vltage m utput pt, m nput pt, ut ut
Sees-Sees xample C ample wth an un-bpassed emtte ac small sgnal equvalent ccut e:83h 3 Feedback
Feedback Netwk wth z-paamete e:83h 3 Feedback 3 v Z v Z v z educe equvalent ccut
Clse lp analss e:83h 3 Feedback 4 ] [ Output mpedance s : nput mpedance s : he clse lp tansadmttance gan s heee, hen pen lp tansadmttance gan s and ut n OL OL p p CL s p s z g g z g g g g g v gv v Z v
Fnal n and ut ' n [ // n // g ]// // ' ut [ z ut // C OP ]// C e:83h 3 Feedback 5
Feedback Stuctue Shunt Shunt e:83h 3 Feedback 6 we get nd, whee Clse Lp ansmpedance Gan Gan Calculatn : CL
nput/output esstance Shunt Shunt nput esstance: n Output esstance Clsed lp utput esstance wth ze nput vltage ut m nput pt, m utput pt, ut e:83h 3 Feedback 7
Shunt-Shunt xample C ample ac small sgnal equvalent ccut Shunt-Shunt cnnectn und! -paamete e:83h 3 Feedback 8
e:83h 3 Feedback 9 F F F Feedback Netwk -paamete mdelng
Fm nput pt, F OP CL S S // C g F F // g OP // nd m utput pt, L OP F // g // Open lp tanmpedance gan : F Wth eedback act C // // C L // L F F S // the clse lp tansmpedance gan :, n ut F // OP C OP OP F // OP // ltage Gan : L s s s n e:83h 3 Feedback 3
Feedback Stuctue Shunt Sees e:83h 3 Feedback 3 we get nd, whee Clse Lp Cuent Gan Gan Calculatn : CL
nput/output esstance Shunt Sees e:83h 3 Feedback 3 nput esstance: n Output esstance Clsed lp utput esstance wth ze nput vltage / m utput pt, m nput pt, ut ut
Summa Feedback Stuctue Clse lp gan nput mpedance Output mpedance Paamete used Sees- Shunt Sees- Sees Shunt- Shun Shunt- Sees e:83h 3 Feedback 33 n n n n ut ut ut ut h-paamete z-paamete -paamete g-paamete
Supplementa Ω kω kω C kω Fnd the nput and utput esstance m - w pt netwk, and - Ccut the e:83h 3 Feedback 34
Ccut he e:83h 3 Feedback 35 Ω Ω k v v v v v v v C ut b s ut n b b s b s b b s n, nd ~ ] //[ ] [ and but whee //
w Pt Netwk e:83h 3 Feedback 36 v Z v Z v z
e:83h 3 Feedback 37 Ω Ω k v v C C ut ut n n ut n b b s OL b b s ~ // ~ // he Open Lp ansadmttance Gan s und b settng eedback sgnal