Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronic Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

question about gain in microwave amplifier

Status
Not open for further replies.

ayhz2002

Member level 3
Joined
Jun 3, 2002
Messages
54
Helped
4
Reputation
8
Reaction score
3
Trophy points
1,288
Activity points
358
hi guys:
I designed a single stage amplifier at 5.5 ghZ. I designed the matching networks with smith chart by hand and by using serenade.The matching networks have balanced stubs (open stubs). My design was based on available power gain at 7 dB. Each matching network gives two solutions. When I check the magnitude of S21, sometimes I find it 7.12 dB or 7.29 db or 6.82 db. Can you tell me why?
I don't understand the excess gain I'm geting above 7 dB, why?
I was accurate as much as I can when I designed the matching networks by hand and by serenade. The matching netwroks from serenade and by hand were very close.

any help
thanks
ayhz2002
 

flatulent

Advanced Member level 5
Joined
Jul 19, 2002
Messages
4,629
Helped
489
Reputation
980
Reaction score
150
Trophy points
1,343
Location
Middle Earth
Activity points
46,689
12 paramaters

These gains seem close enough to 7.00. I suspect that the S12 parameter causes the interaction between the input and output matching values.
 

g86

Full Member level 4
Joined
Jan 21, 2003
Messages
212
Helped
11
Reputation
22
Reaction score
7
Trophy points
1,298
Location
On top of antenna :))
Activity points
2,232
They are actually close and should be acceptable. Remember the mathcing network may also provides some gain because the RF amplefire gain not only depends upon the S21 of device but also on reflected power in the input as well as output.

:!: :idea: :?:

ayhz2002 said:
hi guys:
I designed a single stage amplifier at 5.5 ghZ. I designed the matching networks with smith chart by hand and by using serenade.The matching networks have balanced stubs (open stubs). My design was based on available power gain at 7 dB. Each matching network gives two solutions. When I check the magnitude of S21, sometimes I find it 7.12 dB or 7.29 db or 6.82 db. Can you tell me why?
I don't understand the excess gain I'm geting above 7 dB, why?
I was accurate as much as I can when I designed the matching networks by hand and by serenade. The matching netwroks from serenade and by hand were very close.

any help
thanks
ayhz2002
 

rainer

Member level 1
Joined
Jul 22, 2002
Messages
41
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,286
Location
new york
Activity points
237
It's correct! Infact if you work with the available gain you are introducing an input mismatch, and so due to variation of the input network your input mismatch can change. As a consequence the gain can change.

Bye!
 

Status
Not open for further replies.
Toggle Sidebar

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top