help me to understand

I found this info from a book of RF design. The impedance determination is given here. I don't understand about which formula he has used to derive input & output impedance. This is for small signal amplifier. I am thinking to build RF pre amp around 100~300 Mhz. Hence guidance will help me go further.

hi,

the formulas can be found in the US patent #3493882 granted to the AVANTEK people back in 1970.

see free online patent link here: https://www.freepatentsonline.com/3493882.pdf

basically the circuit is a special case of the well known passive bridged T circuit in which an active device (the transistor) is included to make it a wideband amplifier.
see for this latter topic another US patent #3100877
( https://www.freepatentsonline.com/3100877.pdf )

you can find useful info on this circuit here: https://www.electronics-tutorials.com/amplifiers/broad-band-amplifiers.htm
and also here: **broken link removed**

the analysis of this circuit is also included in Rohde/Vendelin book: Microwave Circuit Design Using Linear and Nonlinear Techniques, what you can borrow from most university or technical libraries or from your local library using inter-library service.

rgds
unkarc

Really very informative material. I think i will need ur more help as i am newbie to RF.
I tried to press the helped me button. But got the message "unautorised".

Hi unkarc,
I will find the book "Rohde/Vendelin book: Microwave Circuit Design Using Linear and Nonlinear Techniques" with some friends or in the library. O r i will buy it.
Let me know where exactly the information lies in the book. This will help me to ask my friend to check the info when he visits university library as he is member of the same. Then i will also check with some other resources. Finally i will buy the book if it is good or useful. The price is US $79.95 is quite expensive i think.

Hi,

sorry but I have not seen / read that book, I have seen it referenced at rfglobalnet by Vendelin where amplifier feedback questions is dealt with, and Vendelin recommended his own book ! on their forum.

**broken link removed**

however I have another book from Rohde in which this single stage feedback amplifier is discussed and I will make a copy of those pages and have them scanned, ok? probably tomorrow I will upload them here if all comes out ok. if not, then next Monday at the latest. The book is : RF/Microwave circuit design for wireless applications, by Rohde and Newkirk, published by John Wiley in 2000.

I recommend another book which is both practical and theoritical and costs $50 at ARRL : Experimental methods in RF design by Hayward, Campbell and Larkin;
and another one also at ARRL for $40: Introduction to Radio Frequency design by Hayward; see this link for both books:
https://www.arrl.org/catalog/?categ...rds=hayward&SearchWords.x=11&SearchWords.y=12

Of course your friend should bring the Vendelin book from the library too :|
Maybe the two books I refer to are also available in libraries.

rgds unkarc


see this link:

@jaya000

Hi, here are 6 scanned pages from the Rohde/Newkirk book I referred to you in an earlier post. It deals with single stage resistive feedback amplifiers (calculation and simulation). Now hopefully you may have enough resources to tinker on

rgds
unkarc

unkarc,
U hv taken so much pain to help me. Thanks for the same. I will buy vendaline book & another arrl book. This will be good for my referance & study.