ltp: --- version 1.1 01.11.00 ______________________________________________________________________________________________________ vi telefilter application note tfs 248d - 1/2 ______________________________________________________________________________________________________ vi telefilter vectron international, inc. potsdamer stra?e 18 267 lowell road d 14 513 teltow / germany hudson, nh 03051 / usa tel: (+49) 3328 4784-52 / fax: (+49) 3328 4784-30 tel: (603) 598-0070 fax: (603) 598-0075 e-mail: tft@telefilter.com e-mail: vti@vtinh.com vi telefilter reserves the right to make changes to the product(s) and/or information contained herein without notice. no liab ility is assumed as a result of their use or application. no rights under any patent accompany the sale of any such product(s) or infor mation. 1. general the filter has to be driven single ended. it is matched to 50 ? . the termination impedances are : input: 630 ? || -5,5 pf output: 600 ? || -5,6 pf 2. theoretical matching the values of the matching elements which are given below are calculated from the source and load impedance. if the values of the matching elements are not equal to standard values the best standard values/best combination of standard values are given in brackets. circuit 1 l2 output 50 ohm c2 input 50 ohm c1 l1 saw 2,3,4,5,7,8,9,10 6 1 l1 = 88 nh (82 nh / 56 nh+33 nh) l2 = 87 nh (82 nh / 56 nh+33 nh) c1 = 15 pf c2 = 15 pf circuit 2 l3 output 50 ohm l4 input 50 ohm l2 l1 saw 2,3,4,5,7,8,9,10 6 1 l1 = 56 nh l2 = 56 nh l2 = 27 nh l4 = 27 nh both matching circuits are theoretically possible, but the first circuit is used in our final measurements. the calculation was made without consideration of parasitics, so the elements which have to be used on the pcb are slightly different from the stated.
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