Download presentation
Presentation is loading. Please wait.
Published bySusan Rich Modified over 6 years ago
1
vs vb cc VDD M9 M12 M11 Iref M1 M2 vo vin- vin+= voQ = vo CL M3 M4 M13
2
DC gain: Av(0)={gm1*(ro6,8||ro2,4)} * {gm10*(ro10||ro11)
=Av1(0) * Av2(0) With Miller simplification: p1 = -1/{(Av2*Cc + Cgs10 +…)*(ro6,8||ro2,4)} -1/{Av2*Cc*(ro6,8||ro2,4)} p2 - gm10/{CL+Cc+Cdb10+Cdb11} BW = |p1| GBW = Av(0)*BW gm1/Cc
3
But Miller simplification gets rid of bridge cap, hence hides zero.
Going back to schematics, examine vo1 io vo io = vo1*(sCc – gm10) vo = io/(sCLtot + go) =vo1*(sCc – gm10)/(sCLtot + go) z1 +gm10/Cc
4
wp1 gm10/CL A1(s)A2(s) A1(s) wp2 wz1 A2(s) w 0dB (s/z1 - 1) A(s)A(0) (s/p1 - 1)(s/p2 - 1) UGF GBW
5
Phase Margin: PM = 180 +(A(s))= 180 +A(s) = 180 +(s/z1-1) - (s/p1-1) - (s/p2-1) = 180 – atan(GBW/z1) – 90 – atan(GBW/|p2|) = 90 – atan(gm1/gm10) – atan(GBW/|p2|) Make GBW < 0.5 |p2| Make gm1 < 0.1 gm10
6
In the previous, we assumed to be frequency-independent.
How can we do that? Examine 3 cases: Buffer connection Resistive feedback Capacitive feedback
7
vs vb cc =1 VDD VDD VDD M9 M12 M11 Iref M1 M2 vo vin+= voQ Vin- = vo
CL vb M3 M4 vo cc R _ + M5 M6 M10 M7 M8 vin2 =1
8
vs vb cc VDD VDD VDD M9 M12 M11 Iref M1 M2 vin- vo vin+= voQ CL M3 M4
9
vs vb cc VDD VDD VDD M9 M12 M11 vo Iref vin- M1 M2 vin+= voQ CL Rf M3
Ri cc R M5 M6 M10 M7 M8 vin2
10
This is s-dependent. To create an s-independent b an, place a Cf in parallel with Rf, with Cf*Rf = Cin-*Ri. Then, is real.
11
vs vb cc VDD VDD VDD M9 M12 M11 Iref M1 M2 vo vin- vin+= voQ CL M3 M4
12
vs vb cc VDD VDD VDD M9 M12 M11 vo Iref vin- M1 M2 vin+= voQ CL Cf M3
Ci cc R M5 M6 M10 M7 M8 vin2
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.