how can o design a wideband amp??

• Nov 20, 2003

• #1

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wjnbry

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wideband amp

Help me please?
i wan to design a 6GHz amp working from 5 to 7GHz.
i have never designed this sort of amp.
i am looking for these topics and some success designs.
thank you!

 

• Nov 20, 2003

• #2

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Element_115

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The common method is :
1) Find a FET that works to your Spec
(Note that Gain is the trade for Bandwidth!)

2) The input should go Lange Coupler w/the 2 output ports
going to a FET each (with the match networks of course)
The other port shuld be terminated with a Good 50 Ohm
load.

3) Then optimize the input and output networks to meet your
Spec.

4) recombined the FET's w/ another Lange Coupler.(Also treminated)


______
input--> | |---50Ohm
| |
50Ohm-| | --> Output
|______|


Hope this helps
Good Luck

 

• Nov 20, 2003

• #3

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costox

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This is NOT really wideband. When you say wideband, it's usually >10 GHz bandwidth. If you look at www.ieeexplore.ieee.org, wideband amp are usually a "distributed amplifier".

Now I notice that the other reply is not really helping because there are so many way to design your amp (7GHz, 2 GHz bandwidth).

So instead of giving you some trivial instructions which won't help you much, I'll tell you this: use @DS. There are many good example (and design guide) in it. And pick the book:
Designing microwave circuits by exact synthesis / Brian J. Minnis.

If this doesn't help you, I don't know what will !

 

• Nov 20, 2003

• #4

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musasu

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10 mhz to 500 mhz amp circuit and design theory...


URL **broken link removed**

bye

 

• Nov 20, 2003

• #5

BigBoss

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wjnbry said:

Help me please?
i wan to design a 6GHz amp working from 5 to 7GHz.
i have never designed this sort of amp.
i am looking for these topics and some success designs.
thank you!

Click to expand...

What kind of amplifier do you intend to design? Low Noise , High Gain , High Power ? Please be specific..

What is your flatness ? What are your reflections ? Cost ? Technology ? Reliability ? Productibility ? etc etc..

If you inform us more specific , we may help you..

 

• Nov 21, 2003

• #6

flyhigh

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I agree this is not wideband requirement in nature, and also much more data is needed to give resonably close answer to particular situation. Maybe even some amps available on the market can be used in your case? If I remember correctly, one of Mini Circuit's ERA stil has some very good performances it this range as a general low-power device? Maybe someone can update this more precisely, I used them some time ago and had lost the information.

 

• Nov 21, 2003

• #7

Kit-the-great

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There is no problem to design 5-7GHz low power (up to 10 mW) amplifier. The really problem is to matching high power FET's (on 1W output for ex.) In this case You must design a very complex matching structure, because the:
1. Zin and Zout of high power FETs is low-Ohm
2. S12 too large, because the FET's gate too width.

Best regards,
Kit-the-great

 

• Nov 24, 2003

• #8

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wjnbry

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many thanks for all of up my good friends!
the amp's Pout is 24dbm,ripple<1dB.
i want to design it with 2 stages of fet(fhc057, FUJITSU) in MIC.
i've been worked in rf major for 2 yeas.
please give me some similar designs and examples.
best regards to you!

 

• Nov 24, 2003

• #9

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HO_220

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Hi.
you can use MMIC such as ERA-MAR and Gali amplifiers for these specs.
It is easy to use these.
Bests.

 

• Nov 24, 2003

• #10

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AL0117

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Hi wjnbry,

what would be Pout = 24 dBm, nominal power or P1dB?
The Era, Mar and Gali's has maximum output power rated to 18dBm (P1dB), so even if the freq range is suitable for you, they can't be used.

I don't find any kind of info about the fhc057, is still in production? What is the P1dB of it?

regards, Al

 

• Nov 25, 2003

• #11

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wjnbry

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FLC057WG
P1dB = 27.0dBm
High Gain: G1dB = 9.0dB(Typ.)
design goal:
Gain=17dB(2 stages)
Ripple<1dB(5~7GHz)
P1dB > 24dBm

FLC057WG
C-Band Power GaAs FET
S-PARAMETERS
VDS = 10V, IDS = 125mA
FREQUENCY S11 S21 S12 S22
(MHZ) MAG ANG MAG ANG MAG ANG MAG ANG
500 .973 -47.9 7.249 147.9 .016 60.6 .545 -20.4
1000 .941 -85.1 5.946 121.8 .026 38.1 .519 -38.2
2000 .912 -129.5 3.846 86.0 .033 8.9 .514 -66.2
3000 .897 -151.8 2.675 62.2 .033 -8.5 .562 -86.5
4000 .889 -164.8 2.058 44.1 .032 -17.6 .618 -101.2
5000 .881 -176.2 1.712 27.8 .033 -25.1 .658 -113.0
6000 .869 171.6 1.506 11.2 .033 -31.0 .689 -125.1
7000 .847 159.0 1.339 -6.1 .035 -39.4 .717 -138.5
8000 .816 148.5 1.199 -21.6 .033 -41.3 .745 -149.3
9000 .787 139.7 1.125 -35.4 .037 -41.0 .773 -157.4
10000 .740 129.4 1.149 -49.4 .045 -40.5 .796 -163.1


at 4 GHz,it's unstabality.

 

• Nov 25, 2003

• #12

BigBoss

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Without nonlinear model , it's not possible to find Pout of this transistor.
S-Parameters are only valid in small signal operating area.
Data's are not sufficient..

 

• Nov 25, 2003

• #13

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AL0117

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I recommand the following lecture:
"MESFET Power Amplifier Design:Small Signal Approach" (How to design a Power Amplifier without a large signal device model?)

you can d/l it from :

hxxp://eesof.tm.@gilent.com/pdf/amp_ss.pdf

(x=t, @=a)

regards, Al

 

• Dec 30, 2004

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costox

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Just for those who read all the way down here...
For TRULY WIDEBAND, (or Ultra-wideband), and I'm talking about 20GHz or even 40 GHz bandwidth, search for "Distributed Amplifiers".

Thanks.

 

• Dec 30, 2004

• #15

abdoeng

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wjnbry said:

Help me please?
i wan to design a 6GHz amp working from 5 to 7GHz.
i have never designed this sort of amp.
i am looking for these topics and some success designs.
thank you!

Click to expand...

hi,i try to simulate amp of fet atf36077 with band 8:12 ghz,u can use it in band 5 to 7 ,it is stable,but for wide band u must use multible match using stub,i can upload u with one of my trial design
regards