Help me start designing 5.8GHz RF amplifier

hi all, please assist me, i want design rf amp following this spec;

f=5.8ghz
gain=>/=20dB
I/O r.loss <-10
modulation =FSK
class = ?
matching = stub
board = FR4 microstrip
software = ADS

im stuck now, where should i start?

5.8GHz RF Amp Design

is it a power amplifier or driver , or LNA

and if it is a PA what is the max output power ?

khouly

Re: 5.8GHz RF Amp Design

cyconx12 said:

hi all, please assist me, i want design rf amp following this spec;

f=5.8ghz
.........................
modulation =FSK
........................

Click to expand...

fmin=......?
fc=5.8 Ghz;
fmax=.....?

Re: 5.8GHz RF Amp Design

Hi,

I suggest to refer to Guillermo Gonzales book:

Microwave Transistor Amplifiers: Analysis and Design.
I should help for your design.

Re: 5.8GHz RF Amp Design

it is RF power amp, the max output is following ISM standard that i not sure ^^. can it be 20W or some figure less? i will check the standard later

Added after 57 minutes:

mirabella: start 5.725ghz, center 5.8ghz, stop 5.825ghz

actually the amplifier will be used in receiver system..so in my opinion the power level required by the amplifier is following system power level itself. according to the power budget that have been calculated, rf amp must be operating at spec as mentioned. here attached is the system look like, and my rf amp is as circled by red colour.

other problem is i am using conditionally stable FET transistor, what is the best matching technique, can anyone propose.. i tried conjugate match, but it is not easy as mentioned in many book i read.

sincerely i fell much better after 8 hours i left my post for the first time then u guys come drop me hi..thanks a lot ^^

5.8GHz RF Amp Design

from the figure this amplifier is called a gain stage , this responsible of giving high gain to the signal after the LNA

about the 20 W , this is very high power not realistic figure , i think u can say it is 20dBm not 2o W

about the stability u need to draw us source and load stability circiles , and then select the stable region on smith chart , what is the transistor ur using

khouly

Re: 5.8GHz RF Amp Design

This is a very confusing block diagram.

So, from the antenna the received signal is amplified by an LNA followed by an RF Amplifier (20W or 20dB or both !?).

After that, a Power Divider (!?) split the signal in two feeding two Band Pass Filters (5.75GHz and 5.85GHz), when actually you already specified that the start frequency is 5.725GHz, center 5.8GHz, stop 5.825GHz.

The two detected paths signals goes to the demodulator. So, there is a detector followed by a demodulator !?.

Re: 5.8GHz RF Amp Design

Hi,

Makes sence only if FSK demodulator is acctually a simple comparator (decission if a signal is 5.75GHz or 5.85GHz). But yes, I am equally sceptical how this "system" will work, and equally puzzled what is its purpose of it in the first place?

flyhigh

Re: 5.8GHz RF Amp Design

sorry for giving u guys wrong info.actually the freq band as i mentioned is placed in ISM band applied in my country. that is the standard freq for the system.i forgot to mention that the BW of both rf amp and LNA are approx 1Ghz each.so it is make sense for both filter right..well im in circuit level, the only i focus is rf amp.pls dun ask me the system blocks, im not in system level,someone else design this.