Output Differential impedance of ADL5336

Question

Hi, 
 Can I assume the output differential impedance of VGA1 is 200 Ohms & VGA2 is 100 Ohms in ADL5336. This is quite confusing from the datasheet as in datasheet page 1 it mentions: "The output of each VGA can drive 100 Ω loads to 5 V p-p maximum." 
 Pratap

EZAdministrator · Accepted Answer

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EZ Admin

ADIApproved · Answer

Hi- 
 I moved this question about the ADL5336 to the RF Components Community. Someone here should be able to assist you. 
 Regards, 
 AndyR 
 EngineerZone Community Manager

jdobler · Answer

Hi Pratap, 
 The output impedance of the ADL5336 is very small; 1 Ohm for VGA1 and 3.5 Ohms for VGA2 (please see the specifications on page 3). 
 The load impedance that each VGA drove during characterization is what you have stated: 200 Ohms for VGA1 and 100 Ohms for VGA2. 
 Although the sentence "The output of each VGA can drive 100 Ohm loads to 5 Vpp maximum" is also true. You don't have to load VGA1 with 200 Ohms as VGA1 can drive 100 Ohms quite well also. The reason that VGA1 drove 200 Ohms during characterization was in it intended to be cascaded with VGA2 and VGA2 has a 200 Ohm input impedance (the same as VGA1). 
 Please note: VGA1 and VGA2 are NOT the same; this is not really a dual channel part but is intended to be a cascadable part. 
 Hope this helps, 
 Joel

Electronic Design Services - PartnerZone

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Output Differential impedance of ADL5336