Path: utzoo!utgpu!watserv1!watmath!att!att!pacbell.com!mips!hal!mark
From: mark@mips.COM (Mark G. Johnson)
Newsgroups: sci.electronics
Subject: Re: A question about a PLL synth loop filter
Message-ID: <42642@mips.mips.COM>
Date: 2 Nov 90 13:45:41 GMT
References: <1990Oct31.210242.20619@aplcen.apl.jhu.edu> <12890@chaph.usc.edu>
Sender: root@mips.COM
Lines: 25


     O---VVVVV----+-------+------O
           R1     |       |
                  |       >
                  |       >  R2
                  |       >
                 ---      |
                 --- C1   |
                  |       |
                  |      ---
                  |      --- C2
                  |       |
     O------------+-------+------O


For a first cut at a design, you can save some effort by using simplifying
approximations:

       Pole at  (approx)  T = ((R1+R2) * C2)
       Zero at  (approx)  T = (R2 * C2)
       Pole at  (approx)  T = (R1 * C1)
-- 
 -- Mark Johnson	
 	MIPS Computer Systems, 930 E. Arques M/S 2-02, Sunnyvale, CA 94086
	(408) 524-8308    mark@mips.com  {or ...!decwrl!mips!mark}