Switched-Capacitor Circuits - University of Toronto
Switched-Capacitor Circuits - University of Toronto
Switched-Capacitor Circuits - University of Toronto
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<strong>University</strong> <strong>of</strong> <strong>Toronto</strong><br />
High-Q Biquad Filter<br />
• Input K1C1 : major path for lowpass<br />
• Input K2C1 : major path for band-pass filters<br />
• Input K3C2 : major path for high-pass filters<br />
• General transfer-function is:<br />
Hz () (50)<br />
• If matched to the following general form<br />
Vo z () K3z -----------<br />
Vi() z<br />
2<br />
+ K1K5+ K2K5 – 2K3z + K3– K2K5 <br />
z 2<br />
= – ----------------------------------------------------------------------------------------------------------------<br />
+ K4K5+ K5K6 – 2z+<br />
1– K5K6 <br />
Hz ()<br />
<strong>University</strong> <strong>of</strong> <strong>Toronto</strong><br />
=<br />
a2z 2<br />
+ a1z + a0 z 2<br />
– -------------------------------------<br />
+ b1z + b0 High-Q Biquad Filter<br />
K1K5 = a0 + a1 + a2 K2K5 = a2 – a0 K3 = a2 K4K5 = 1 + b0 + b1 K5K6 = 1 – b0 • And, as in lowpass case, can set<br />
K4 = K5 = 1 + b0 + b1 • As before, K4 and K5 approx oT « 1 but K6 <br />
1 Q<br />
(51)<br />
43 <strong>of</strong> 60<br />
© D. Johns, K. Martin, 1997<br />
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44 <strong>of</strong> 60<br />
© D. Johns, K. Martin, 1997
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