lecture24 ee474 otac filters
TRANSCRIPT
![Page 1: Lecture24 Ee474 Otac Filters](https://reader034.vdocuments.us/reader034/viewer/2022051108/545e8bf9af79593c758b48eb/html5/thumbnails/1.jpg)
Sam PalermoAnalog & Mixed-Signal Center
Texas A&M University
ECEN474: (Analog) VLSI Circuit Design Fall 2010
Lecture 24: OTA-C Filters
![Page 2: Lecture24 Ee474 Otac Filters](https://reader034.vdocuments.us/reader034/viewer/2022051108/545e8bf9af79593c758b48eb/html5/thumbnails/2.jpg)
Announcements
• Project• Preliminary report due Nov 19• No layout• Focus is on good circuit design
• No Class on Monday 11/15
2
![Page 3: Lecture24 Ee474 Otac Filters](https://reader034.vdocuments.us/reader034/viewer/2022051108/545e8bf9af79593c758b48eb/html5/thumbnails/3.jpg)
Agenda
• OTA-C Filters• Material is related primarily to Project #3• Full class on filters offered (458, 622)
3
![Page 4: Lecture24 Ee474 Otac Filters](https://reader034.vdocuments.us/reader034/viewer/2022051108/545e8bf9af79593c758b48eb/html5/thumbnails/4.jpg)
OTA-C Filter Applications
• Hard-disk drives require linear phase filters (>100MHz)• RF systems require filters in the GHz range• Wireless xcvrs intermediate frequency (IF) filters (>100MHz)• Often used with variable gain amplifiers (VGAs) for
automatic-gain control (AGC) to maximize dynamic range• Low noise, low power, and high linearity are required
4Hard-Disk Drive Receiver Front-End
OTA-C Filter [Pandey]
![Page 5: Lecture24 Ee474 Otac Filters](https://reader034.vdocuments.us/reader034/viewer/2022051108/545e8bf9af79593c758b48eb/html5/thumbnails/5.jpg)
OTA-Based Active Resistor
5
mi
i
imoi
gIVR
VgII1
==
==
[Schaumann]
![Page 6: Lecture24 Ee474 Otac Filters](https://reader034.vdocuments.us/reader034/viewer/2022051108/545e8bf9af79593c758b48eb/html5/thumbnails/6.jpg)
OTA-Based Active Resistors
6
[Schaumann]
![Page 7: Lecture24 Ee474 Otac Filters](https://reader034.vdocuments.us/reader034/viewer/2022051108/545e8bf9af79593c758b48eb/html5/thumbnails/7.jpg)
OTA-Based Integrator
7
sCg
VV m=
1
2 Ideally
• Finite OTA ro causes a non-zero pole• OTA Co reduces integration constant
( ) oo
m
gCCsg
VV
++=
1
2
[Schaumann]
![Page 8: Lecture24 Ee474 Otac Filters](https://reader034.vdocuments.us/reader034/viewer/2022051108/545e8bf9af79593c758b48eb/html5/thumbnails/8.jpg)
Lossy gm-C Integrator (1st-Order LPF)
8
( ) omio
m
m
m
ggCCCsg
VV
gsCg
VV
22 2
1
1
2
2
1
1
2
++++−=
+−=
ecapacitancoutput andinput zero-non and resistanceoutput OTA finite gConsiderin
Ideally
[Schaumann]
![Page 9: Lecture24 Ee474 Otac Filters](https://reader034.vdocuments.us/reader034/viewer/2022051108/545e8bf9af79593c758b48eb/html5/thumbnails/9.jpg)
Fully Differential Lossy gm-C Integrator
9
• Pseudo-Differential
• Fully Differential• 2C because full gm
current goes to each side
• Why just C here?
[Schaumann]
![Page 10: Lecture24 Ee474 Otac Filters](https://reader034.vdocuments.us/reader034/viewer/2022051108/545e8bf9af79593c758b48eb/html5/thumbnails/10.jpg)
OTA-Based Inductor
10
21
211
2
221
1
2
2
211
1
112
221
1
1
mmeff
effmm
mm
mm
m
m
ggCL
sLgg
sCZ
sCY
Ygg
Z
VI
ggIV
VgIVgI
=
==
=
=
=
==
If
equations two these From
[Schaumann]
![Page 11: Lecture24 Ee474 Otac Filters](https://reader034.vdocuments.us/reader034/viewer/2022051108/545e8bf9af79593c758b48eb/html5/thumbnails/11.jpg)
Differential Grounded Inductor
11
[Schaumann]
![Page 12: Lecture24 Ee474 Otac Filters](https://reader034.vdocuments.us/reader034/viewer/2022051108/545e8bf9af79593c758b48eb/html5/thumbnails/12.jpg)
Second-Order Filter
12
22
21
1min
21
21
1
2
21
1min
22
1
min
21
21
1
2
1
min
1
1
oo
m
mm
Q
m
in
LP
oomm
Q
in
BP
Qss
CCgg
CCgg
CRss
CCgg
VV
Qss
Cgs
CCgg
CRss
Cgs
VV
ωω
ωω
+
+
−=
+
+
−=
+
+
=
+
+
=
[Silva]
![Page 13: Lecture24 Ee474 Otac Filters](https://reader034.vdocuments.us/reader034/viewer/2022051108/545e8bf9af79593c758b48eb/html5/thumbnails/13.jpg)
Differential Second-Order Filter
13
[Mohieldin]
![Page 14: Lecture24 Ee474 Otac Filters](https://reader034.vdocuments.us/reader034/viewer/2022051108/545e8bf9af79593c758b48eb/html5/thumbnails/14.jpg)
OTA Output Resistance Effects
14
[Silva]
![Page 15: Lecture24 Ee474 Otac Filters](https://reader034.vdocuments.us/reader034/viewer/2022051108/545e8bf9af79593c758b48eb/html5/thumbnails/15.jpg)
OTA Non-Dominant Pole Effects
15
[Silva]
![Page 16: Lecture24 Ee474 Otac Filters](https://reader034.vdocuments.us/reader034/viewer/2022051108/545e8bf9af79593c758b48eb/html5/thumbnails/16.jpg)
OTA Parasitic Capacitor Effects
16
[Silva]
![Page 17: Lecture24 Ee474 Otac Filters](https://reader034.vdocuments.us/reader034/viewer/2022051108/545e8bf9af79593c758b48eb/html5/thumbnails/17.jpg)
OTA-C BPF Modeling Simulations
17
4th-Order BPF
[Silva]
![Page 18: Lecture24 Ee474 Otac Filters](https://reader034.vdocuments.us/reader034/viewer/2022051108/545e8bf9af79593c758b48eb/html5/thumbnails/18.jpg)
4th-Order Filter Example
18
[Mohieldin]
![Page 19: Lecture24 Ee474 Otac Filters](https://reader034.vdocuments.us/reader034/viewer/2022051108/545e8bf9af79593c758b48eb/html5/thumbnails/19.jpg)
Magnitude, Phase, and Group Delay
19
[Silva]
![Page 20: Lecture24 Ee474 Otac Filters](https://reader034.vdocuments.us/reader034/viewer/2022051108/545e8bf9af79593c758b48eb/html5/thumbnails/20.jpg)
Optimization: Non-Dominant Pole & DC Gain
20
[Silva]
![Page 21: Lecture24 Ee474 Otac Filters](https://reader034.vdocuments.us/reader034/viewer/2022051108/545e8bf9af79593c758b48eb/html5/thumbnails/21.jpg)
Useful References
• “Design of Analog Filters” by R. Schauman(Filters Textbook)
21
![Page 22: Lecture24 Ee474 Otac Filters](https://reader034.vdocuments.us/reader034/viewer/2022051108/545e8bf9af79593c758b48eb/html5/thumbnails/22.jpg)
Next Time
• Analog Applications• Variable-Gain Amplifiers• Switch-Cap Filters, Broadband Amplifiers
• Bandgap Reference Circuits• Distortion
22