Hello John,
Your results look very interesting. The big variation with input level
shows how important it is to get that right. Incidentally, I didn't
blame the CMOS for the 1/f^3 slope, as that was 18dB below the OCXO's
phase noise. The divider output dominated from ~100Hz outwards, and
showed 1
Bruce wrote:
A little more detail is required such as:
1) What was the divided down output of the 74AC163 compared with?
The E5052B contains 2 uncorrelated test systems, and uses its 2 internal
synthesisers (with separate 10MHz ref OCXOs) as references. The signal
under test is split at the inp
Hi
That plot is very similar to what I have seen on AC gates.
The usual mumble words apply - that was > 15 years ago and semiconductor
processes have changed a bit since then.
Bob
On Feb 26, 2010, at 5:54 AM, John Miles wrote:
> Hi, Garry --
>
>> I knew from other people's measurements that 7
Hi, Garry --
> I knew from other people's measurements that 74AC was capable of better
> than -160dBc/Hz when used to make a phase detector at 10MHz, but I
> wanted to do a quick feasibility check on a divider for an application a
> couple of years ago.
>
> The 74AC163 was powered from a linear be
Garry
A little more detail is required such as:
1) What was the divided down output of the 74AC163 compared with?
2) An image of the breadboard would also be useful.
3) A circuit diagram showing component values and manufacturer's part nos.
The idea being to provide sufficient information so
From: "Garry Thorp"
Subject: Re: [time-nuts] Advice on 10 MHz isolation/distribution /
Phase Noise of 74AC gates
The attached plot shows the 12.5MHz phase noise plus that of the 100MHz
OCXO. The divider phase noise tracks 18dB below the OCXO at low offsets
as expected, before i
Hello Bob,
My 15mA estimate for the output stage was based on AC coupling the
output, which is how I connected it. The IC is then sourcing 25mA into
100R for half the time and sinking 25mA the rest of the time, so the
mean supply current drawn is 12.5mA. The extra is to allow for the IC's
dissipa
s would still be a very useful accessory, even if the reverse
isolation results were down to 60dB.
Pete
On Feb 20, 2010, at 12:46 PM, life speed wrote:
> From: Pete Rawson
> Subject: Re: [time-nuts] Advice on 10 MHz isolation/distribution
> To: Discussion of precise time and frequency mea
> I have been thinking about how to make the measurement. I don't
> normally measure OCXO phase noise. I buy them to spec and lock
> my synthesizer to them, measuring phase noise at microwave
> frequencies using an older Agilent E5500 system with an 8254 (?)
> signal generator reference, which i
From: Bruce Griffiths
Subject: Re: [time-nuts] Advice on 10 MHz isolation/distribution
(Clay)
The calculation is useful to help eliminate amplifiers that will not
meet the phase noise floor specs.
The amplifiers that remain will then need to be tested/measured for
their actual phase noise
From: Pete Rawson
Subject: Re: [time-nuts] Advice on 10 MHz isolation/distribution
To: Discussion of precise time and frequency measurement
Message-ID: <1027d446-fe23-45a7-88ad-1cfd339c4...@earthlink.net>
Content-Type: text/plain; charset=us-ascii
Clay,
I would really like to have
life speed wrote:
From: Bruce Griffiths
Subject: Re: [time-nuts] Advice on 10 MHz isolation/distribution
Its easy to calculate a lower bound to the amplifier phase noise floor
from the signal level at the output and the amplifier output noise due
to feedback resistors together with the
From: Bruce Griffiths
Subject: Re: [time-nuts] Advice on 10 MHz isolation/distribution
Its easy to calculate a lower bound to the amplifier phase noise floor
from the signal level at the output and the amplifier output noise due
to feedback resistors together with the amplifier input voltage
life speed wrote:
If I can believe the simulation (a big if) the ADA4899-1 can provide 90 dB
isolation at 10 MHz, rolling up to 70 dB at 100 MHz, when configured with a
gain of +2
The subcircuit model provided by ADI is useless for noise, unfortunately. I
guess I'll have to build and measure
Clay,
I would really like to have a copy of your test board for this effort.
I'm sure it will be a challenging layout. But it could be a very handy
piece of hardware. Supporting a PCA order would easy to do.
Pete Rawson
On Feb 19, 2010, at 6:17 PM, life speed wrote:
> If I can believe the simul
If I can believe the simulation (a big if) the ADA4899-1 can provide 90 dB
isolation at 10 MHz, rolling up to 70 dB at 100 MHz, when configured with a
gain of +2
The subcircuit model provided by ADI is useless for noise, unfortunately. I
guess I'll have to build and measure, which I don't mind
Hi
. and thus if you drive it from a low impedance node you can get pretty
good isolation.
Bob
On Feb 19, 2010, at 5:59 PM, Bruce Griffiths wrote:
> life speed wrote:
>> Message: 6
>> From: Pete Rawson
>> Subject: Re: [time-nuts] Advice on 10 MHz isolation/distributi
life speed wrote:
Message: 6
From: Pete Rawson
Subject: Re: [time-nuts] Advice on 10 MHz isolation/distribution
Clay,
Analog devices AD4899-1 voltage noise = 2nV/rtHz @ 10Hz; GBW = 300MHz.
Pete Rawson
That is an interesting part.
So, how does one think about reverse isolation in
Message: 6
From: Pete Rawson
Subject: Re: [time-nuts] Advice on 10 MHz isolation/distribution
>Clay,
>
>Analog devices AD4899-1 voltage noise = 2nV/rtHz @ 10Hz; GBW = 300MHz.
>
>Pete Rawson
That is an interesting part.
So, how does one think about reverse isolation in a feedba
Clay,
Analog devices AD4899-1 voltage noise = 2nV/rtHz @ 10Hz; GBW = 300MHz.
Pete Rawson
On Feb 19, 2010, at 12:05 PM, life speed wrote:
> Any opinions on the suitability of the TI OPA820 as a 10 MHz distribution
> amp? The voltage noise is only 7 nV/rtHz @ 100 Hz (gain=2, I'll be using
> g=
ehalf Of life speed
Sent: Friday, February 19, 2010 2:06 PM
To: time-nuts@febo.com
Subject: Re: [time-nuts] Advice on 10 MHz isolation/distribution
Any opinions on the suitability of the TI OPA820 as a 10 MHz distribution
amp? The voltage noise is only 7 nV/rtHz @ 100 Hz (gain=2, I'll be
Any opinions on the suitability of the TI OPA820 as a 10 MHz distribution amp?
The voltage noise is only 7 nV/rtHz @ 100 Hz (gain=2, I'll be using g=1), which
is the best I've seen so far for a wideband amp. Not as good as the discrete
transistor circuit, but it would use alot fewer parts. It
Message: 6
Date: Fri, 19 Feb 2010 15:17:44 -
From: "Garry Thorp"
Subject: Re: [time-nuts] Advice on 10 MHz isolation/distribution
Hello Clay,
Joining in this discussion at a rather late stage - have you
considered using 74AC series gates as buffers? They provide reasonable
iso
9 February 2010 17:30
To: 'Discussion of precise time and frequency measurement'
Subject: Re: [time-nuts] Advice on 10 MHz isolation/distribution
Hi
Yup, that works.
A couple of *very* minor points:
-
My guess is that your output stage will be pulling a bit more than 15
output gate.
Also provides a high pass filter to reduce some of that low freq PS noise,
especially if the input is AC coupled correctly.
ws
***
[time-nuts] Advice on 10 MHz isolation/distribution
Bob Camp lists at cq.nu
Fri Feb 19 17:30:04 UTC 2010
Previous message: [time-nuts] Advice
ick.
Not real sure that Clay is a big fan of lots of harmonics or of filters.
Bob
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Garry Thorp
Sent: Friday, February 19, 2010 10:18 AM
To: time-nuts@febo.com
Subject: Re: [ti
Hello Clay,
Joining in this discussion at a rather late stage - have you
considered using 74AC series gates as buffers? They provide reasonable
isolation and have surprisingly low phase noise.
A single 74AC04 inverter gives over 40dB reverse isolation at 10MHz, so
3 cascaded gates would give
life speed wrote:
The TI THS3201-EP was looking pretty good for a high speed opamp. But the
input current noise graph doesn't go below 100 KHz and is climbing pretty
steeply at that point.
Clay
Most current feedback opamps tend to have high inverting input noise
current at low frequenc
Hi
The reason to consider transformers is that they cut out 2/3 of the parts in
the circuit and significantly reduce the noise.
Bob
On Feb 18, 2010, at 6:33 PM, life speed wrote:
> Message: 5
> Date: Thu, 18 Feb 2010 17:13:55 -0500
> From: "Bob Camp"
> Subject: Re: [t
The TI THS3201-EP was looking pretty good for a high speed opamp. But the
input current noise graph doesn't go below 100 KHz and is climbing pretty
steeply at that point.
Clay
___
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To unsubscribe,
Message: 5
Date: Thu, 18 Feb 2010 17:13:55 -0500
From: "Bob Camp"
Subject: Re: [time-nuts] Advice on 10 MHz isolation/distribution
(Clay)
To: "'Discussion of precise time and frequency measurement'"
Message-ID: <13d264786a8a41e781bb4e53c1dd9...@vect
Hal Murray wrote:
The problem is modulation of the reference signal via relative
movement of the transformer guts. While I understand there are ways
to 'harden' magnetic devices, my application is far too sensitive to
even consider a magnetic approach given the availability of
alternatives.
Hi
Vibration modulates lead inductance. That's true even on SMT semiconductors..
It's true big time for leaded parts of the axial persuasion. Weather the amount
of change matters to you is another thing entirely.
If you stick with NPO even for the bypass caps, the piezo stuff is not going to
> The problem is modulation of the reference signal via relative
> movement of the transformer guts. While I understand there are ways
> to 'harden' magnetic devices, my application is far too sensitive to
> even consider a magnetic approach given the availability of
> alternatives. Any spurious
still an issue that directly impacts
what you are trying to do.
Bob
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of life speed
Sent: Thursday, February 18, 2010 4:47 PM
To: time-nuts@febo.com
Subject: Re: [time-nuts] Advice on 10 MHz is
Message: 5
Date: Thu, 18 Feb 2010 11:11:18 -0800
From: Hal Murray
Subject: Re: [time-nuts] Advice on 10 MHz isolation/distribution
(Clay)
> Thank you, but I require a circuit without transformers
> for reasons of vibration susceptibility.
Is the problem wires moving relative to eac
> -Original Message-
>
>
> > Lastly, my customer, the system designer, would now like to be able to add
> > a switch function to the
> 10 MHz distribution. I will have to check and see if switching of bias
> current to these two-stage
> transistor amp circuits can accomplish this fun
life speed wrote:
Date: Thu, 18 Feb 2010 15:22:40 +1300
From: Bruce Griffiths
Clay
What's the effect of assigning the same label (Vout_2) to the outputs of
both output amplifiers as shown in your circuit schematic?
Bruce
Hi Bruce,
Duplication of the Vout_2 net labels (copy and paste is great
Date: Thu, 18 Feb 2010 15:22:40 +1300
From: Bruce Griffiths
Clay
What's the effect of assigning the same label (Vout_2) to the outputs of
both output amplifiers as shown in your circuit schematic?
Bruce
Hi Bruce,
Duplication of the Vout_2 net labels (copy and paste is great) did not help the
uency measurement
Subject: [time-nuts] Advice on 10 MHz isolation/distribution SRS FS700
An easy way to make a 10 MHz distribution amplifier is the one from Stanford
Research.
Manual can be find at :
http://www.thinksrs.com/downloads/man.htm
Download FS700
The schematics are in the back of the
> Thank you, but I require a circuit without transformers
> for reasons of vibration susceptibility.
Is the problem wires moving relative to eachother within the transformer or
the whole transformer moving relative to the local magnetic field?
Does it help to pot things in epoxy or varnish or ..
Message: 6
Date: Thu, 18 Feb 2010 06:53:47 -0800 (PST)
Subject: [time-nuts] Advice on 10 MHz isolation/distribution SRS FS700
An easy way to make a 10 MHz distribution amplifier is the one from Stanford
Research.
Manual can be find at :
http://www.thinksrs.com/downloads/man.htm
Download FS700
at.
Bob
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Electronics and Books
Sent: Thursday, February 18, 2010 9:54 AM
To: Discussion of precise time and frequency measurement
Subject: [time-nuts] Advice on 10 MHz isolation/distribution
An easy way to make a 10 MHz distribution amplifier is the one from Stanford
Research.
Manual can be find at :
http://www.thinksrs.com/downloads/man.htm
Download FS700
The schematics are in the back of the manual.
Met vriendelijke groeten
Regards
electronicsandbo...@yahoo.com
http://www.Electro
Clay
What's the effect of assigning the same label (Vout_2) to the outputs of
both output amplifiers as shown in your circuit schematic?
Bruce
life speed wrote:
Date: Fri, 12 Feb 2010 15:32:55 -0500
From: Bob Camp
Subject: Re: [time-nuts] Advice on 10 MHz isolation/distribution
Hi
life speed wrote:
Date: Fri, 12 Feb 2010 15:32:55 -0500
From: Bob Camp
Subject: Re: [time-nuts] Advice on 10 MHz isolation/distribution
Hi
There are a few differences between what you are simulating and the schematics
Bruce posted earlier. The collectors of the input stages (q1, q4 and q7
One issue with opamps may be the distortion as few of the high frequency
ones have distortion data for more than 2Vpp output.
Its can be little optimistic to scale from this if they plot distortion
vs input (or output level) or give IP2 and IP3 specs.
+10dB in 50 ohms requires 4V pp at the opam
Hi
There's also the "throw everything at it" approach.
Use something like common base stages for the input and op amps for the
outputs. Boost the level into the op amps and pad it at the outputs. You might
get what you need. More parts than a pure op amp design, more current. Likely
easier to
The only data available seems to be John Ackermann's measurements on the
TADD-1 distribution amp.
Unfortunately the opamp used is now obsolete or about to be.
Most recent discrete designs (not the HP5087 amplifiers) that I have
seen phase noise data for, have significantly lower flicker phase no
Hi
I have no data, but I believe that in the real application, the phase noise
would not be degraded by a good low noise RF op amp / buffer amp. About all you
can do for flicker noise data is to look at what they do supply and make an
guess based on how the noise rolls up over the range they do
In the later version the input amplifier has a gain of 2x and the output
amplifiers have unity gain.
Whilst the reverse isolation (and output impedance) can be improved by
using a complementary symmetry emitter follower output stage, one has to
ask at that point is the performance gain worth i
Hi
Since it's the input stage, it's likely the point most impacted by a higher
flicker noise part. That might make one want to look at alternatives.
Of course, it's not real clear that a super low noise amp is needed in this
case.
Bob
On Feb 12, 2010, at 8:46 PM, Bruce Griffiths wrote:
> Th
The series RC to ground keeps the high frequency impedance seen by Q1
and Q7 low so that the base current noise which increases significantly
as the frequency approaches the ft of these transistors.
However such a series RC network does little to suppress the the rise
due to gain peaking.
A shun
life speed wrote:
I seem to not be accomplishing much isolation from output to input, as well as
output to output. Have I fumbled PSPICE somehow? For each simulation, Vac was
set separately, with V1=0.707V at the input, while V6=0V at the output (sim1).
Then V1=0V, and V6=0.01V (sim2).
Hi
There are a few differences between what you are simulating and the schematics
Bruce posted earlier. The collectors of the input stages (q1, q4 and q7) seem
have to come unglued from the bases of the output stages. The 95 ohm / 100 nf
roll off networks seem to have vanished from the emitters
I seem to not be accomplishing much isolation from output to input, as well as
output to output. Have I fumbled PSPICE somehow? For each simulation, Vac was
set separately, with V1=0.707V at the input, while V6=0V at the output (sim1).
Then V1=0V, and V6=0.01V (sim2).
clay_schem1.pd
rom: Bob Camp
> Subject: Re: [time-nuts] Advice on 10 MHz isolation/distribution
> (Clay)
>
> Hi
>
> I suspect your noise spike can be cured by a series R-C to ground from the
> junction of Q1 base, Q7 base and all the other stuff. Something is going to
> have to s
Message: 3
Date: Thu, 11 Feb 2010 23:02:30 -0500
From: Bob Camp
Subject: Re: [time-nuts] Advice on 10 MHz isolation/distribution
(Clay)
Hi
I suspect your noise spike can be cured by a series R-C to ground from the
junction of Q1 base, Q7 base and all the other stuff. Something is going to
Hi
I suspect your noise spike can be cured by a series R-C to ground from the
junction of Q1 base, Q7 base and all the other stuff. Something is going to
have to set a high frequency roll off. With no coils some combo of R and C is
going to have to do it.
You might also try returning all of t
life speed wrote:
Message: 2
Date: Fri, 12 Feb 2010 12:12:29 +1300
From: Bruce Griffiths
The output (collectors of Q5, Q6 emitter of Q4) of the input amplifier
sets the dc voltage at the inputs ( Q1 base, Q7 base respectively) of
the output amplifiers.
The circuit consists of a unity gain input
Message: 2
Date: Fri, 12 Feb 2010 12:12:29 +1300
From: Bruce Griffiths
The output (collectors of Q5, Q6 emitter of Q4) of the input amplifier
sets the dc voltage at the inputs ( Q1 base, Q7 base respectively) of
the output amplifiers.
The circuit consists of a unity gain input amplifier (Q4, Q
life speed wrote:
Message: 1
Date: Thu, 11 Feb 2010 12:42:27 -0500
From: "Bob Camp"
Subject: Re: [time-nuts] Advice on 10 MHz isolation/distribution
amplifier(Clay)
Hi
I really should learn how to read the whole message
Cancel the second request on vibe info.
Thu, 11 Feb 2010 12:42:27 -0500
> From: "Bob Camp"
> Subject: Re: [time-nuts] Advice on 10 MHz isolation/distribution
> amplifier(Clay)
>
> Hi
>
> I really should learn how to read the whole message
>
>
>
> Cancel the second request on
life speed wrote:
Message: 2
Date: Thu, 11 Feb 2010 07:54:40 -0500
From: Bob Camp
Hi
Implementing that circuit without using a hybrid would be a bit of a challenge.
Bob
Message: 6
Date: Fri, 12 Feb 2010 04:09:08 +1300
From: Bruce Griffiths
Yes implementing an exact copy without using a hybri
Message: 1
Date: Thu, 11 Feb 2010 12:42:27 -0500
From: "Bob Camp"
Subject: Re: [time-nuts] Advice on 10 MHz isolation/distribution
amplifier(Clay)
Hi
I really should learn how to read the whole message
Cancel the second request on vibe info.
-
The gotcha with
s@febo.com
Subject: Re: [time-nuts] Advice on 10 MHz isolation/distribution (Clay)
Message: 6
Date: Thu, 11 Feb 2010 12:38:58 -0500
From: "Bob Camp"
Subject: Re: [time-nuts] Advice on 10 MHz isolation/distribution
amplifier(Clay)
Hi
I'll grab the one on the hybrid.
In this ca
Message: 6
Date: Thu, 11 Feb 2010 12:38:58 -0500
From: "Bob Camp"
Subject: Re: [time-nuts] Advice on 10 MHz isolation/distribution
amplifier(Clay)
Hi
I'll grab the one on the hybrid.
In this case hybrid is referring to a construction technique.
The circuit shown was origin
oun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of life speed
Sent: Thursday, February 11, 2010 12:27 PM
To: time-nuts@febo.com
Subject: Re: [time-nuts] Advice on 10 MHz isolation/distribution
amplifier(Clay)
Message: 2
Date: Thu, 11 Feb 2010 07:54:40 -0500
From: Bob Camp
Hi
Im
oun...@febo.com] On
Behalf Of life speed
Sent: Thursday, February 11, 2010 12:27 PM
To: time-nuts@febo.com
Subject: Re: [time-nuts] Advice on 10 MHz isolation/distribution
amplifier(Clay)
Message: 2
Date: Thu, 11 Feb 2010 07:54:40 -0500
From: Bob Camp
Hi
Implementing that circuit without using a
Message: 2
Date: Thu, 11 Feb 2010 07:54:40 -0500
From: Bob Camp
Hi
Implementing that circuit without using a hybrid would be a bit of a challenge.
Bob
Message: 6
Date: Fri, 12 Feb 2010 04:09:08 +1300
From: Bruce Griffiths
Yes implementing an exact copy without using a hybrid would be diffic
Yes implementing an exact copy without using a hybrid would be difficult.
However for 10MHz use, its probably not too difficult since that
isolation amplifier is intended for a 100MHz signal and the requirement
is for 10MHz operation.
If the transistor ft's are reduced by a factor of 10 or so
Hi
Implementing that circuit without using a hybrid would be a bit of a challenge.
Bob
On Feb 10, 2010, at 11:30 PM, Bruce Griffiths wrote:
> Clay
>
> Circuit schematic for a more recent JPL isolation amplifier design is
> attached.
>
> Bruce
>
> life speed wrote:
>> Avoiding transformers
Clay
If the first stage has a voltage gain of 2x then the total dc current
can be reduced as the output stages no longer need to drive the feedback
100 ohm resistor connected to ground at RF. The attached circuit
schematic also includes faster input transistors in each 3 transistor
feedback c
Attn: John Ackermann
Not sure what happened to produce 2 identical posts but as far as I can
tell I only posted this once.
Bruce
Bruce Griffiths wrote:
Clay
Circuit schematic for a more recent JPL isolation amplifier design is
attached.
Bruce
Clay
Circuit schematic for one of the JPL isolation amplifiers is attached.
Unfortunately (apart from the few I and others may have) these
transistors are difficult to obtain.
However modern equivalents could be substituted.
Bruce
life speed wrote:
Avoiding transformers and inductors will ma
Clay
You could try something like the attached circuit schematic.
Austron used buffer amplifiers like this albeit without the
complementary symmetry output stage.
There are no transformers and the dc gain is low.
Simulated reverse isolation at 10MHz is around 120dB.
Simulated crosstalk between
n signal at the far end.
Bob
--
From: "life speed"
Sent: Wednesday, February 10, 2010 10:03 PM
To:
Subject: Re: [time-nuts] Advice on 10 MHz isolation/distribution amplifier
Avoiding transformers and inductors will make it virtually impos
Avoiding transformers and inductors will make it virtually impossible to
achieve very low phase noise as the dc gain from say the base of any
transistor in the chain to the output will degrade the flicker phase
noise. Using transformers or using an inductor to shunt any collector
resistors redu
ot;life speed"
Sent: Wednesday, February 10, 2010 8:27 PM
To:
Subject: [time-nuts] Advice on 10 MHz isolation/distribution amplifier
Hello everyone,
I am new to this list, happened across it while searching on distribution
amplifiers.
I need to design a 10 MHz isolation/distribution amplifie
life speed wrote:
Hello everyone,
I am new to this list, happened across it while searching on distribution
amplifiers.
I need to design a 10 MHz isolation/distribution amplifier with two outputs for
a high-vibration wide temperature range environment. I was considering using a
design based
Hello everyone,
I am new to this list, happened across it while searching on distribution
amplifiers.
I need to design a 10 MHz isolation/distribution amplifier with two outputs for
a high-vibration wide temperature range environment. I was considering using a
design based on the NIST article
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