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

user5840537

Part Number: LM7171
Other Parts Discussed in Thread: THS3091, TINA-TI

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

over 3 years ago

0 Michael Steffes over 3 years ago

Guru 47485 points

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.

0 user5840537 over 3 years ago in reply to Michael Steffes

Intellectual 255 points

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

0 Hasan Babiker31 over 3 years ago in reply to user5840537

TI__Genius 15555 points

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