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Unformatted text preview: Synthesizers © 2009 G. Zhang70dBc spur120dBc/Hz Q1,Q2 Q3 1MHz 65dB signal jammer ! A PLL with two forward chargepump/loop filter paths as shown below, assume small signal linear model; ! Question1: derive the open loop transfer function, find poles and zeros; ! Question2: sketch the Bode’s plot of loop transfer: magnitude and phase (estimate with reasoning is fine, no need to be exact, assume C1 is much bigger than C2); ! Questions 3:generally C1 is too big to be integrated on chip, is there a way to reduce C1 by 10x, without changing PLL loop transfer function/bandwidth (hint, Icp1, Icp2 don’t have to be the same)? ECE264D homework1, Prob#2 UP Icp1 C1 Page 2 ECE264D RF Frequency Synthesizers © 2009 G. Zhang PFD UP/DN DN Icp1 UP DN Icp2 Icp2 + VCO Kv ideal voltage adder C2 R1 fref Div by N...
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 Spring '11
 Song
 Frequency, Signal Processing, phase noise, RF Frequency Synthesizers, G. Zhang, ECE264D RF Frequency

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