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18th October 2019, 21:58
 Replies
 3
 Views
 279
Closed: How to find cutoff frequency of the circuits
Hi, I want to find cutoff frequency of the two attached circuits. I just want to know is there any quicker way to find it. For the circuit2 I got it as 1/(2*pi*R*C) but I don't see the same in...

13th October 2019, 18:42
 Replies
 1
 Views
 185
Closed: When to connect RF Bypass capacitor, and a Resistor in place of RF choke?
H, RF choke (Inductor) is used to isolate AC signal and DC like wise DC blokcing capacitor is also used for the same purpose.
156021 *figures taken from Internet.
1.As shown in figure (1), when... 
13th October 2019, 14:24
Thread: how to get higher P1dB,in point
by circuitking Replies
 2
 Views
 229
Closed: how to get higher P1dB,in point
Hi, for example a circuit has P1dB,in at 10 dBm. What all possibility/techniques do I have to change it to 10 dBm. Thanks.

12th October 2019, 14:13
Thread: Loadpull for Differential PA
by circuitking Replies
 9
 Views
 632
Closed: Re: Loadpull for Differential PA
How are you saying that output is shorted, is it because the C terminal of Ideal_balun connected to ground?. Also, I already connected 'dcblock' and 'dcfeed', where else should they be connected?
... 
5th October 2019, 23:58
 Replies
 3
 Views
 334
Closed: How the stability analysis in analog and RF design related?
Hi, we measure stability of a circuit in terms of phase margin and gain margin in analog circuits where as for RF circuit analysis kfactor >1 and delta <1. In some way, is there any relation between...

2nd October 2019, 14:12
 Replies
 10
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 656
Closed: Re: S parameter extraction for MOSFET internal parameters
This is really a good tip.

1st October 2019, 11:12
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 6
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 582
Closed: Re: what is the significance of the transit frequency and maximum frequency of oscill
In the case of DA the maximum gainBW product is 0.8*fmax.
Source[MESFET Distributed Amplifier Design Guidelines] 
30th September 2019, 14:39
Thread: Why S22 curve is like this
by circuitking Replies
 9
 Views
 697
Closed: Re: Why S22 curve is like this
I know that bias is not shown. If at all bias is connected, where should it be connected?.
Anyway, I found out where It should be connected without disturbing biasing. 
30th September 2019, 12:08
Thread: Why S22 curve is like this
by circuitking Replies
 9
 Views
 697
Closed: Re: Why S22 curve is like this
I have seen in a book, a capactior is also used. I am still wondering how bias is provided when capacitor is kept in the signal path as shown in the figure.
155792 
27th September 2019, 01:49
 Replies
 9
 Views
 850
Closed: Re: Parasitic capacitor extraction: huge value
Well, I think I found an answer for my question. https://www.edaboard.com/showthread.php?319853SpectrecalculatorHowtocalculateinputcapacitanceofa2portsnetwork

26th September 2019, 21:22
 Replies
 3
 Views
 359
Closed: Re: What happens to output power and 3 BW in this circuit
The ports connected to the capacitors providing input power of 10 dBm each (loaded LC ladder section). I kept ports to find the ZP and SP at those points. I expect to see more output power at the...

26th September 2019, 15:25
 Replies
 10
 Views
 656
Closed: Re: S parameter extraction for MOSFET internal parameters
Actually this is the book name "Distributed Power Amplifiers for RF and Microwave Communications Narendra KumarAndrei Grebennikov" and those equations are given from MESFET or HEMT. They look similar...

26th September 2019, 01:00
 Replies
 10
 Views
 656
Closed: Re: S parameter extraction for MOSFET internal parameters
I am not sure, where/how do I verify which model it is?

26th September 2019, 00:56
 Replies
 8
 Views
 784
Closed: Re: How do you choose input power while doing loadpull?
After reading this post https://www.edaboard.com/showthread.php?386008PowerAmplifierDesign, it makes me think.
What is the pout that is shown at optimum load , Is it p1dB(out) or maximum power... 
26th September 2019, 00:36
 Replies
 10
 Views
 656
Closed: S parameter extraction for MOSFET internal parameters
Hi, In this book Radio Frequency Integrated Circuit Design Second Edition John W. M. Rogers Calvin Plett author mentions equation for MOSFET internal capacitors, resistors and gm. How accurate are...

26th September 2019, 00:24
 Replies
 9
 Views
 850
Closed: Re: Parasitic capacitor extraction: huge value
Hi Sutapanaki, could you explain how do we simulate for Cgs and Cgd?
There is so much confusion around for me.
1. I can use tran simuation and find the time domain signal and verify the... 
25th September 2019, 12:50
Thread: Loadpull for Differential PA
by circuitking Replies
 9
 Views
 632
Closed: Loadpull for Differential PA
There are few posts on this but I just clarify it properly for my problem.
https://www.edaboard.com/showthread.php?363089LoadPullforDifferentialPA&highlight=ideal+balun... 
21st September 2019, 10:51
 Replies
 1
 Views
 276
Closed: Identical gain stages in Distributed amplifier:are they paralllel or cascaded?
Hi, The identical gain stages in DA, if I have 5 of them, can I say that it is a 5 stage DA? but we use " stage" notation only to cascade connections, in which the output of one stage is given to...

21st September 2019, 08:09
 Replies
 1
 Views
 225
Closed: Frequency as a variable in an instance
Hi,I want to define an instance in virtuoso, say PORT, whose real and imaginary part change with frequency and see its behavior on smith chart using sp simulation. Re(z)=f(freq) and imag(z)==f(freq)....

18th September 2019, 10:26
 Replies
 4
 Views
 410
Closed: Re: In distributed amplifiers, is it total input capacitance of the gain stage or Cgs
If the line is modeled with a discrete set of inductors and capacitors, then it is referred to as an artificial transmission line.
Please refer Radio Frequency Integrated Circuit Design, Second... 
15th September 2019, 18:45
 Replies
 3
 Views
 359
Closed: What happens to output power and 3 BW in this circuit
Hi, I calcaulated L and C values for a butterworth filter, to get 3 dB BW of 50 GHz and attenuation of 6 dB at 60 GHz. Next, I gave 10 dBm input power and I got the expected result.
Again I took... 
15th September 2019, 03:15
 Replies
 5
 Views
 673
Closed: Re: How to calculate bandwidth for this circuit, including lower and higher cut off f
True, I didn't connect gate capacitors. Then how do we call this structure, cascode or stack? So if I dont connect those gate capacitors what changes would be there in performance parameters?

12th September 2019, 21:27
 Replies
 5
 Views
 673
Closed: How to calculate bandwidth for this circuit, including lower and higher cut off freq
Hi, for the attached stack structures I already added the capacitors after doing simplifications. I was thinking I should multiply the capacitance with the resistances I marked.
1. Is it correct,... 
11th September 2019, 12:43
 Replies
 2
 Views
 323
Closed: In PA, if the bias is VDD then how can swing be 2*VDD with inductive load
Hi, From the below link I read that when we have inductive load, for example, in CS amplifier the output voltage swing can be (2*VDD), if VDD is the supply voltage
... 
11th September 2019, 12:35
 Replies
 5
 Views
 404
Closed: Re: What is the difference between BVDSS and BVDS
Thanks. How is substrate breakdown voltage is denoted, any short form? I am looking for its value in the PDK but I find it nowhere.
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