Switched-Capacitor Circuits - University of Toronto
Switched-Capacitor Circuits - University of Toronto
Switched-Capacitor Circuits - University of Toronto
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Fully-Differential Filters<br />
• Most modern SC filters are fully-differential<br />
• Difference between two voltages represents signal<br />
(also balanced around a common-mode voltage).<br />
• Common-mode noise is rejected.<br />
• Even order distortion terms cancel<br />
v 1<br />
– v1<br />
nonlinear<br />
element<br />
nonlinear<br />
element<br />
v p1<br />
v n1<br />
=<br />
=<br />
<strong>University</strong> <strong>of</strong> <strong>Toronto</strong><br />
<strong>University</strong> <strong>of</strong> <strong>Toronto</strong><br />
2 3 4<br />
k1v + k<br />
1 2v1 + k3v1 + k4v1 + <br />
+<br />
-<br />
v diff<br />
2<br />
=<br />
3 5<br />
2k1v + 2k<br />
1 3v1 + 2k5v 1 + <br />
– k1v + k<br />
1 2v1 – k3v1 + k4v1 +<br />
Fully-Differential Filters<br />
C 1<br />
2 2<br />
3<br />
CA 2 4 <br />
+<br />
<br />
C2 1<br />
1 +<br />
Vi() z<br />
Vo() z<br />
<br />
1 1<br />
-<br />
-<br />
C2 2<br />
C 1<br />
2<br />
C 3<br />
C 3<br />
C A 2<br />
1<br />
1<br />
31 <strong>of</strong> 60<br />
© D. Johns, K. Martin, 1997<br />
32 <strong>of</strong> 60<br />
© D. Johns, K. Martin, 1997
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