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How to determine Zin, Yout for RF transistor, from A parameters

One of the basic problems with text books, is that they are typically written by those that went from the chain of school, to uni to learn, then stay at uni to teach. They pretty much invariably have no idea how real, commercial design is done.

Another problem, is IEEE papers. People piss about with some supposed theory, show some results that appear to match, and claim wonderful things for their theory. Pretty much all of them on phase noise, are wrong. The results are either in error, coincidental, delusionary or lies. Yes, some have to be lies as there is no other rational explanation when the theory is so far out to lunch.

Just one example is here from Behzad Razavi (who writes text books):

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- "A Study of Phase Noise in CMOS Oscillators,"

Pretty much everyone treats an oscillator as if it is an amplifier with a signal at the oscillator amplitude and frequency added to a noise signal. This is fundamentally flawed. An oscillator is an automatous signal generator. As soon as the noise moves the phase/frequency, of the oscillator output, the mix products change from what they would have been if the signal was an independent one, because the oscillator, dah...has changed frequency. This results in the inability to add up all noise generators by calculating the effect of each one separately. Second, they all attempt an analysis by using the power series describing the amplitude nonlinearity. This is fundamentally flawed as well. The oscillator frequency is set by is loop phase being zero. When the noise changes the value of the nonlinear capacitances in the circuit, the loop phase changes, hence there is direct FM modulation. One therefore needs to calculate the phase response with amplitude, not amplitude distortion. The reality is that, it is impossible to design high performance oscillators that beat the competition without using simulation tools (PSSN). Manual calculations are just too difficult.

Indeed, the above Razavi paper includes "multiplicative" noise of Osc frequency X noise frequency due to nonlinear amplitude mixing. However, Sin(w_o.t).Sin(w_n.t) is amplitude noise not phase noise. The zero xings of the the product due to the osc don't change. "multiplicative" noise has only an indirect effect on final phase noise. Simply clueless, yet these are the guys teaching the newbies.

The crunch is all here:

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So Jim, baring in mind that I have now been around 9 years at

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and extensively investigated 100s of oscillator topologies and 100,000s of osc simulations, it would, pretty much, make me a world leading authority on high performance oscillators, not that I am ever one of those types that brag on NGs. :-)

-- Kevin Aylward

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- SuperSpice
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Reply to
Kevin Aylward
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Denied.

In fact, I will give you a challenge. I will pay you $1,000, and you will pay me $100 if you can beat me on a design for a 100MHz (ease of testing) oscillator. The basic conditions being.

1 No experimental work. The oscillator must work correctly first time build.

2 You design based solely on S parameters of the transistors, data sheet and paper calculations, with no DC, or TRAN simulations, because you don't have the spice model.

3 I design based solely on the spice model using Cadence, including PSS and PSS Noise, TRAN and DC.

4 A noise performance and current spec will be agreed. You win if I don't produce a design that is at least 1/4 your design's current and 10dB lower phase noise.

It would be like liking sweets from a baby. Trust me.

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The reality is, most "RF guys", can't design a minskirt. I have interviewed many. Their minds are filled with nebulous frequency domain claptrap, they don't actually understand that transistor level design is about volts, amps and time. Other than a simply resister bias, they are usually clueless.

-- Kevin Aylward

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- SuperSpice
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Reply to
Kevin Aylward

On a sunny day (Sat, 6 May 2017 23:39:14 +0100) it happened "Kevin Aylward" wrote in

My response, a question, show me a RF circuit you actually build lately? Preferably GHz?

That is predicatable, he designs sjips. With all respect to JT.

Did you try string theory?

Reply to
Jan Panteltje

On a sunny day (Sun, 7 May 2017 09:21:23 +0100) it happened "Kevin Aylward" wrote in :

You do not need S params, nor Spice to design a `100 MHz osc'. And I hope you mean BUILD a physical working, your slimulation doing better is just that, string theroy.

yer good old JFET |-------------- choke--- + 12 ------------>| | | | |-- | | === C | | L |------------| === | === [ ] | decoupling | | 2C | 1k | ---------------------------------- GND

Worked for me.

You never actually build any RF did you?

Reply to
Jan Panteltje

What do you expect when you post such a lame platitude, Captain Obvious?

Reply to
Cursitor Doom

You will have just incurred Kev's wrath with this remark, John. Expect to be beaten into a pulp by attrition.

Reply to
Cursitor Doom

FMOB! Perish the thought, Kev. ;->

Reply to
Cursitor Doom

ClassD_GateWavScope.jpg

FFS, Tim. Your scope's screen is so scratched it's hard to tell the traces from the scars!

Reply to
Cursitor Doom

Maybe SuperSpice accepts a short verbal description of what you want, and how much it should cost.

--

John Larkin         Highland Technology, Inc 

lunatic fringe electronics
Reply to
John Larkin

That's a remarkably ignorant statement. During my youth slide rules and Smith Charts were taught in high school and college.

For the first 15 years out of school there were no Spice simulators.

You first you village idiot. ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| STV, Queen Creek, AZ 85142    Skype: skypeanalog |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 

     Thinking outside the box... producing elegant solutions. 

"It is not in doing what you like, but in liking what you do that 
is the secret of happiness."  -James Barrie
Reply to
Jim Thompson

A couple of people (TAITIEN, ABRACON) are making 1" square OCXOs with astounding phase noise specs, for around $80. I wonder if they are SC cuts. Does Rakon have anything like that?

We are building a test rig that will slowly walk two edges across each other, D and clk into a super-fast SiGe flipflop. One flop input will be a super-good OCXO. We'll look at the averaged Q output to compute time jitter. So we can measure the jitter of longish time delays cheap.

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Looks like we'll be in the 60 fs RMS sort of range on edge detection, so the OCXO jitter will dominate.

--

John Larkin         Highland Technology, Inc 

lunatic fringe electronics
Reply to
John Larkin

I was toying with the idea of building an XO with extremely low harmonic distortion. It would be a colpitts, like your circuit, but with weak feedback coupling, and a separate low-distortion buffer directly off the crystal.

What I'll probably do is just use one of our DDS-based arbs to make a pretty good sine wave, and lowpass filter the heck out of that.

--

John Larkin         Highland Technology, Inc 

lunatic fringe electronics
Reply to
John Larkin

At least in my youth, linear and circulative slide rules were used in something comparable to high school.

Smith Charts were thought in a technical university not in high school.

Reply to
upsidedown

Tell us more about how things were prior to the Great Flood!

Reply to
bitrex

On a sunny day (Sat, 6 May 2017 11:24:14 -0500) it happened "Tim Williams" wrote in :

....

Unfortunately, you have absolutely no idea whatsoever about modern electronic asic design, and I mean that you are completely clueless on that matter. Your implication that one has to piss about on a breadboard after designing in the simulation universe, is wrong. Period.

Its simply fact that 100,000s of ascis with up to billions of transistors are designed entirely in simulation, and a very large % of them work correctly, first time.

I have given a lecture on this several time before in this NG. Look it up. Some processes cost 1/2 million dollars for a set of masks. Do you really think that a company is going throw that money down the toilet?

Analog ones are more challenging, but essentially, the chief reason, imo, why an analog asic don't work first pass, is because the designer wasn't the full shilling, not that there is any issue with designing in the virtual world.

-- Kevin Aylward

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- SuperSpice
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Reply to
Kevin Aylward

On a sunny day (Sun, 7 May 2017 09:21:23 +0100) it happened "Kevin Aylward" wrote in :

You are clearly completely clueless on modern, high performance oscillator design. Fortunately for those that buy iPhones, TX and RX design is, essentially, all done in the virtual world, otherwise making 50 million a quarter reliably would be truly impossible. Sure, there is may be a bit of manual tweaking but you wont get a contract from Apple without having an army of verification engineers producing documentation on the simulations on the chips you're flogging to them. I actually have a mate who does just that.

yer good old JFET |-------------- choke--- + 12 ------------>| | | | |-- | | === C | | L |------------| === | === [ ] | decoupling | | 2C | 1k | ---------------------------------- GND

Ho hummm...

That is not an oscillator. It, may be in another universe, a part of $5 dick tracy walky talki for children.

What is its phase noise? What is is stability over temperature and power supply variations? How many will be in spec out of a million made? What is its spec? What's its frequency sensitivity to load? ....

I don't build anything today, I haven't for many years. I modied my Marshall amp a while back though. It had a || loop for the effects. Ho humm...

However, I do have an OCXO asic in production that runs up to 100MHz, has a few ppb stability, and flat band phase noise approaching -165db, in a very small package.

How about you?

-- Kevin Aylward

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- SuperSpice
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Reply to
Kevin Aylward

On a sunny day (Sat, 6 May 2017 23:39:14 +0100) it happened "Kevin Aylward" wrote in

-----Orig>>>

I wrote this over 15 yeas ago:

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again, now pay attention to the statement just before the summary.

Address my actual points first. Like,

1 What can NOT be done in spice that MUST be done using S parameters

2 Explain how one does phase noise, distortion, bias design and power optimisation using just S parameters.

I want to know how *you* design high performance, competitive, oscillators using only S parameters.

I have told you how I do it.

-- Kevin Aylward

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- SuperSpice
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Reply to
Kevin Aylward

Indeed, and we no longer use slide rules.

Although, Jim, being that you are somewhat mature now, it may be that you can't avoid relapsing to your childhood...

Indeed, and we now do use Spice

-- Kevin Aylward

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- SuperSpice
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Reply to
Kevin Aylward

And oranges are much better than apples.

Reply to
JM

On a sunny day (Sun, 7 May 2017 20:52:06 +0100) it happened "Kevin Aylward" wrote in :

How ** impressive, and that is why you now need a Russian taxi to lower earth orbit.

2017 - 1969 = 48 years of moving backwards.
Reply to
Jan Panteltje

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