r amp tek amptek inc. 6 de angelo drive, bedford, ma 01730-2204 usa tel: +1 (781) 275-2242 fax: +1 (781) 275-3470 email: sales@amptek.com www.amptek.com the a250f/nf is a high density version of the amptek a250 charge sensitive preamplifier. the input fet is not included and must be added externally. please refer to the a250 specifications for further information. notes 1. the internal feedback resistor r f = 1 g 2. the internal feedback capacitor c f = 0.25 pf sensitivity (gain) = 175 mv//mev (si) 4 v/pc 0.64 v/electron 3. for lower sensitivity applications, c f can be increased externally. 4. the external 1 k resistor from pin 2 to pin 5 provides the fet with a drain current of i ds = 2.75 ma. i ds can be increased by reducing r < 1 k . a250f/nf mechanical dimensions a250f/nf pin configuration a250f/nf single in-line package (sip) 1 n i p . k c a b d e e f o t d e t c e n n o c e b t s u m . t e f e h t f o e t a g e h t 2 n i p . t u p n i o t d e t c e n n o c e b t s u m . t e f e h t f o n i a r d e h t 3 n i pe s a c & d n u o r g 4 n i p) l a c i p y t v 6 - ( s v - 5 n i p) l a c i p y t v 6 + ( s v + 6 n i pt u p t u o a250f/nf pin ? 5 pin ? 4 pin ? 3 +vs -vs pin ? 1 ground & ? case pin ? 2 pin ? 6 output 0.25 ? pf 1 ? g w ) 1k input detector external fet s d g ) r
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