Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics 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.

Explanation why interstage inductor is placed between 2 transistors

Status
Not open for further replies.

MK28

Advanced Member level 4
Joined
Mar 7, 2005
Messages
119
Helped
10
Reputation
20
Reaction score
7
Trophy points
1,298
Activity points
2,120
hi all,

I've seen some Cascoded LNA design where interstage inductor were placed between 2 transistors. I do not get the clear idea about it !! I am looking for a theoretical explanations for this. Can anyone help......this is really urgent!!

Please, any site or books or journals to get a clear idea ?

MK28
 

flatulent

Advanced Member level 5
Joined
Jul 19, 2002
Messages
4,626
Helped
489
Reputation
980
Reaction score
150
Trophy points
1,343
Location
Middle Earth
Activity points
46,689
interstage matching inductor

This involves what is called "interstage peaking" It goes back to about 1940. There is series peaking and shunt peaking. It forms a filter like structure with the parasitic capacitances of the active devices. You trade off a one pole gentle rolloff response for a flatter one with sharp rolloff.
 

Wilson_yu_chen

Advanced Member level 4
Joined
Jan 27, 2005
Messages
116
Helped
7
Reputation
14
Reaction score
0
Trophy points
1,296
Activity points
1,196
tube cascode amplifier

Hi Professional,

Although I'm a laity in IC design as I'm specilized in GSM RF system, but I'm still
wandering this "pole" in the discussion above can be applied for RF application band ? I heard that LNA is a wideband device comapred to IF programmable amplifier in wireless communication Receive, So
1. How to deside this pole location in frequency in wireless comm.?
2. What's the advantage if works for gentle rolloff way in above discussion, would
it be applicable to wireless comm. system for instance, GSM, BT...

Thanks !!
 

vfone

Advanced Member level 5
Joined
Oct 10, 2001
Messages
5,446
Helped
1,571
Reputation
3,145
Reaction score
1,180
Trophy points
1,393
Activity points
34,590
interstage match

The only reason of the interstage match in a cascode LNA is to increase the gain. But from my experience the LNA become very unstable.
In a vacuum tube cascode amplifier this would help because the gain is lower compared with actual solid-state transistors.
 

Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top