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LM7171: 20MHZ X10 times input ,but the Vpp(out) is attenuate 50%

Prodigy 225 points

Replies: 3

Views: 68

Part Number: LM7171

V1 is DC for Vf=1V,  V2 is sine wave of Vpp=2V, the low V2=0V,The High V2=2V, The V spuppler power is ±15V, but when the frequency is 20Mhz Vout is only  -7V to  +7V,I think its should be  -10V to + 10V

  • Well it is a voltage feedback device, say it is 200MHz GBP, your 2nd stage is at a noise gain of 11, should be about 18MHz F-3dB for small or large signal - you just rolling off. If you need gain of 10 and 20Mhz, use a current feedback 2nd stage. 

    Michael Steffes

  • In reply to Michael Steffes:

    Can you provide a reference schematic? Thank you very much!!!

  • In reply to user5840537:

    Hello,

    Here are two TINA-TI schematics with the initial design you posted and one using a current-feedback amp (THS3091) on the second stage. You can choose a different amplifier based off your requirements, a current feedback amplifier is useful in high gain configurations since it's bandwidth isn't greatly affected by gain. If you choose to use a voltage-feedback amplifier, you will need a part with a greater gain-bandwidth than the LM7171 (at least 220MHZ in this case). You can take a look at this video series for more info on current feedback amplifiers.

    4135.LM7171.TSC

    LM7171+THS3091.TSC

    Best,

    Hasan Babiker

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