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Design >> RF Design >> One stage LNA with MMIC invert phase?
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Message started by imett on Aug 9^th, 2007, 7:15am

Title: One stage LNA with MMIC invert phase?
Post by imett on Aug 9^th, 2007, 7:15am

Hi to everyone,
i'm an unskilled engeneer in RF solution, i've make my first LNA with a MMIC (like avago or HP MSA0886).
The simple LNA have a one stage amplifier but with my lecroy oscilloscope i've see that the signal is inverted, i've make some mistake or it is usual have this invertion?
Mi goal is design a peakdetector for 1GHz, so the simple idea is use an amplifier and a zero bias schottky diode (HSMS285C).
Thanks in advance.
matteo

Title: Re: One stage LNA with MMIC invert phase?
Post by ACWWong on Aug 9^th, 2007, 8:02am

yes, for a single stage common-source amplifier, you would expect the signal inversion (as the gate voltage increase, the device takes more current, which develops more voltage across the load from Vsupply, so Vout decreases).