EE 230 Lecture 28. Nonlinear Circuits using Diodes. Rectifiers Precision Rectifiers Nonlinear function generators

Transcription

1 EE 230 Lecure 28 Nonlinear Circuis using ioes ecifiers Precision ecifiers Nonlinear funcion generaors

2 Quiz 8 f a ioe has a value of S =E-4A an he ioe volage is.65v, wha will be he ioe curren if operaing a T=300K? =? 0.65V

3 An he number is?

4 An he number is?

5 Quiz 8 f a ioe has a value of S =E-4A an he ioe volage is.65v, wha will be he ioe curren if operaing a T=300K? =? 0.65V Soluion: S e V V E 5 E -4 e 0.65 E -4 8E0 800uA

6 eview from Las Time: Linear Circuis The eal Elecronics Worl Nonlinear Circuis esisive Neworks MOSFET ioe BJT Passive Filers (LC Neworks) All Logic Circuis Comparaors Nonlinear Amplifiers Linearize Nonlinear Circuis (small signal moel) Amplifiers (epenen Sources) Analog o igial Converers (AC) Sensor Acive nerfaces Filers Waveform Generaors igial o Analog Converers (AC) Waveform Generaors

7 eview from Las Time: The ioe Anoe Anoe Cahoe p-ype n-ype Cahoe

8 eview from Las Time: Types of ioes pn juncion ioes V V V V V V Signal or ecifier Pin or Phoo Ligh Emiing LE Laser ioe Meal-semiconucor juncion ioes Zener Varacor or Varicap V V V Schoky Barrier

9 eview from Las Time: The eal ioe 0 if V 0 V 0 if 0 OFF ON ON OFF Vali for >0 0

10 (amps) eview from Las Time: ioe equaion (silicon pn juncion ioes) S e V V ioe Characerisics V (vols) Wiely Use Piecewise Linear Moel

11 (amps) eview from Las Time: A more accurae approximaion o he ioe equaion S e V V ioe Characerisics V (vols) More accurae pn juncion ioe moel: V 0 V 0

12 eview from Las Time: A more accurae approximaion o he ioe equaion S e V V Piecewise Linear Moel V 0 V 0 Equivalen Circui A V C A C Off Sae V A C On Sae

13 eview from Las Time: ioe recifier circui eal ecifier Characerisics f =V M sinω Serves as a recifier very useful funcion!

14 Consier again he basic recifier circui V Analyze wih piecewise linear moel Case = 0 0 V V 0 =0 V vali for V bu V = vali for

15 Consier again he basic recifier circui V Analyze wih piecewise linear moel V 0 V 0 Case 2 V = = - vali for > 0 V - N bu = vali for >

16 Consier again he basic recifier circui V Analyze wih piecewise linear moel Soluion summary: 0 V N V = OUT V N - V N >

17 Performance Limiaions of ioe ecifier Circui ioe recifier circui shif in break poin

18 Performance Limiaions of ioe ecifier Circui ioe recifier circui 0 V N V = OUT V - V > N N

19 Performance Limiaions of ioe ecifier Circui ioe recifier circui 0 V N V = OUT V - V > Consier =V M sinω for N N V M =50V, V M =V an V M =0.5V esire oupu: V M V M

20 Performance Limiaions of ioe ecifier Circui V M Consier =V M sinω for V M =50V, V M =V an V M =0.5V esire oupu: V M

21 Performance Limiaions of ioe ecifier Circui Consier =V M sinω for V M =50V, V M =V an V M =0.5V f V M =50V, he rop causes very lile egraaion in performance f V M =V, he rop causes ramaic egraaion in performance Ampliue shif an uy cycle egraaion

22 Performance Limiaions of ioe ecifier Circui Consier =V M sinω for V M =50V, V M =V an V M =0.5V f V M =0.5V, he rop provies no oupu! Acual oupu

23 Precision ecifier Circui V X (wih nonieal ioe) 0 V V 0 Case Conucing, Op Amp operaing linearly = Vali for >0 an V SATL <V X <V SATH = / > 0 when >0 an V X = + V SATL -0.6 < < V SATH < < V SATH - 0.6

24 Precision ecifier Circui V X (wih nonieal ioe) 0 V V 0 Case Conucing, Op Amp operaing linearly = 0 < < V SATH Case V SATH - 0.6

25 Precision ecifier Circui V X (wih nonieal ioe) 0 V V 0 Case 2 No Conucing, Op Amp saurae low = 0 (since no curren flowing hrough ) Vali for < an V + < V - V X = V SATL =V X -0 < V SATL < an < 0

26 Precision ecifier Circui V X (wih nonieal ioe) Case 2 No Conucing, Op Amp saurae low 0 V V 0 = 0 < 0 vali for Case Case 2 V SATH Case 2 V SATH - 0.6

27 Precision ecifier Circui V X (wih nonieal ioe) 0 V V 0 Case Case 2 V SATH This is he ransfer characerisics of an ieal recifier! Can be use o recify very small signals! Nee a buffer on if any curren is o be provie o a loa!

28 Consier his circui Following an almos ienical analysis, can show V M -V M V M -V M This serves as a precision negaive recifier (no invering recifier)

29 Consier his circui 2 Precision ecifier

30 Consier his circui f >0 V X = so = V X f <0 Precision ecifier V X =0 so = - This is a precision full-wave recifier (recifies posiive signals, invers an recifies negaive signals)

31 Precision Full-Wave ecifier V M V X Precision ecifier -V M V X V M -V M V M -V M

32 Consier his circui (assume ioe is ieal) K 4K 5K f ioe is OFF, =0 f ioe is ON, = -0 4 Serves as a wo-segmen funcion generaor Bu no conrol of he firs slope

33 Consier his circui +2V (assume ioes are ieal) K 0K 2K -V 2 5K f < -V, ON, 2 OFF 0K 0K V OUT = VN K//2K K V = V 6-20 OUT 0K 0K 0K f 2V > > -V, ON, 2 ON V OUT = VN V - K//2K//5K K 5K OUT N V = V 8-8 0K 0K f > 2V, OFF, 2 ON V OUT = VN + + V - 2K//5K 5K OUT N V = V 8 +2 N

34 Consier his circui +2V (assume ioes are ieal) K 0K 2K -V 2 5K 6V -20 V <- N V = 8V -8 -<V <2 OUT N N N N 8V +2 V >2 N - 2 m=8 m=8 m=6 (no o scale) This is a nonlinear funcion generaor

35 Nonlinear Funcion Generaor (assume ioes are ieal) V 2 V V F -2 V -2-2 Assume V 2 > V > V - > V -2 Provies a 5-segmen nonlinear funcion generaor Analysis sraighforwar bu eious ioe funcion generaors like his can be use o conver a riangle wave o a very goo sine wave Performance acually usually beer wih acual ioes since ransiion beween regions is smooher

36 Generalize Nonlinear Funcion Generaor V n n n n- V n- n- 0 k O V -m+ -m+ -m+ F V -m -m -m Assume V n > V n- >...V > 0 > V - > > V -m Provies m+n+ segmen nonlinear funcion Slopes are always posiive an greaer han Can generae arbirary nonlinear ransfer characerisic Acually works beer wih nonieal ioes Can be exene o provie slopes less han Can be furher exene o provie slopes of arbirary sign an arbirary magniue

37 Generalize Nonlinear Funcion Generaor ^ V s ^ V s- ^ s s ^ s- s- V n n n n- k O ^ V -r+ ^ V -r -r+ -r ^ 0 ^ -r+ ^ -r ^ (-θ) ^ θ ^ F V n- V -m+ V -m n- -m+ -m 0 X -m+ -m (-θ) F θ Provies m+n+r+s+2 segmen nonlinear funcion Slopes can be posiive or negaive of any magniue Analysis an esign eious bu sraigh forwar

38 En of Lecure 28