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a 70db amp for a noise source

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zibadun:
I've got a white noise source based on a zenner diode (N-Gen made by Elecraft) which gives -110dbm or so output.  I need to boost the output another 65 to 70 db over a range of 1-60 mhz.   Would an amp based on LMH6503 http://www.ti.com/lit/ds/snosa78d/snosa78d.pdf  set for +70db gain work for this purpose?   

McMonster:
The values given on the first page of the datasheet are for optimistic conditions. Take a look at "Gain Adjustment Range" in electrical characteristics.

zibadun:

--- Quote from: McMonster on December 26, 2012, 07:10:03 pm ---The values given on the first page of the datasheet are for optimistic conditions. Take a look at "Gain Adjustment Range" in electrical characteristics.

--- End quote ---

it says 68 db over 0-30 mhz which is OK with me.  I've ordered some samples. :)

JackOfVA:
70 dB gain in a single stage of LMH6503 at 60 MHz? 

That's not how I read the data sheet. For a gain of 100V/v (40 dB) the bandwidth is 50 MHz (-3dB) and for 70 dB gain the bandwidth is going to be much, much less.

It will also be interesting to build a single stage amp with 70 dB gain at RF frequencies. It will likely turn into an oscillator instead of an amplifier.

I would be inclined to use a cascade of 3 Mini-Circuits GaLi-74 MMIC amplifiers. 50 ohms in/out, quite stable with even a halfway decent layout on the PCB and not all that expensive. Gain will be around 70 dB with 3 in series and the frequency range will be determined by your choice of components and PCB layout, as each amp is good to 1 GHz. 1-60 MHz is trivial with these devices.

Jack

zibadun:
That is what happens when a newb tries to design an amp.  :-//  I suspected 70db would be too much gain for one stage.     The microcircuits monolitic amp looks a lot easier with fewer components and only a single power supply. Thanks for the advice Jack!

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