Guido,
I know that it was not yesterday, the design phase. Having seen Your opinion changed since then, could You suggest something better for a tweaker type old customer of yours? Or, to put it in another way, do you consider it a possible tweak point, looking at it from a general balanced design point of view?
Thanks, George
I know that it was not yesterday, the design phase. Having seen Your opinion changed since then, could You suggest something better for a tweaker type old customer of yours? Or, to put it in another way, do you consider it a possible tweak point, looking at it from a general balanced design point of view?
Thanks, George
Thanks for the quick reply!
I would have some other questions / notes of this type. I was considering the idea of opening a thread at a certain point, maybe it could be useful for others as well. But now, pardon me, I just can't resist, in your opinion exchanging the TLC271 for some newcomers like
LMV 771 from nat.semi or opa725 or max4475 would go in the same direction?
Ciao, George
I would have some other questions / notes of this type. I was considering the idea of opening a thread at a certain point, maybe it could be useful for others as well. But now, pardon me, I just can't resist, in your opinion exchanging the TLC271 for some newcomers like
LMV 771 from nat.semi or opa725 or max4475 would go in the same direction?
Ciao, George
Guido,
Thanks again!
That power supply suggestion is sensible. It was not me who asked about the CR511...
Bocka,
Thanks for the goodwill. In fact, I was looking for these parameters.
The LMV771 seems to be readily available, RR opamp, input bias current is 0.2 pA [against .6 of the tlc], input offset current is 17fA [against 100 fA of the tlc]
What regards 1/f noise, this was what I was hunting for, the LMV771 has en=12.5nV at 100 Hz, against ~300nV of the tlc271.
in for LMV is 1fA, NA for tlc.
Wanted to put up here the noise curves, still fighting with it.
The other opamps perform equally or better. What I wanted to point out that there has happened a revolution lately in the cmos opamp field, and we could profit from it..
Ciao, George
Thanks again!
That power supply suggestion is sensible. It was not me who asked about the CR511...
Bocka,
Thanks for the goodwill. In fact, I was looking for these parameters.
The LMV771 seems to be readily available, RR opamp, input bias current is 0.2 pA [against .6 of the tlc], input offset current is 17fA [against 100 fA of the tlc]
What regards 1/f noise, this was what I was hunting for, the LMV771 has en=12.5nV at 100 Hz, against ~300nV of the tlc271.
in for LMV is 1fA, NA for tlc.
Wanted to put up here the noise curves, still fighting with it.
The other opamps perform equally or better. What I wanted to point out that there has happened a revolution lately in the cmos opamp field, and we could profit from it..
Ciao, George
bocka said:
Hi,
Please not in the DAC design the opamp runs at about 6V. This to ensure the VCXO can be driven easilly up to 4.5V. This value has never been measured, mostly it is between 2 and 3V so 5V could be safely chosen for this opamp. Please adapt power supply then.
Nice opamp, from spec point of view. I bet they all sound different when applied in the PLL, so go ahead and try them all !
best
Re: LED is a low noise component, but not high PSRR.
Hi Jocko.
No, the attached schematic is of our first DAC, published years ago. Indeed, many people seem to have pronblems thinking in the current domain, even more difficult to think PNP since NPN is always taken as examples....
XO DAC bennefits from the same supply as XO2 and 3: < 5nV/SqrrtHz..........
best
Jocko Homo said:
Hi Jocko.
No, the attached schematic is of our first DAC, published years ago. Indeed, many people seem to have pronblems thinking in the current domain, even more difficult to think PNP since NPN is always taken as examples....
XO DAC bennefits from the same supply as XO2 and 3: < 5nV/SqrrtHz..........
best
Carlos, welcome!
I hate it, but I have to point out that I was looking for cmos opamps..
With low input bias & offset currents and unity gain stability.
This BB one, though is not applicable in the special application discussed here, is a "meraviglia' in itself. A new arrival in that wonderful family of stratosferic amplifiers, which started with comlinear. At our job here these things are having a task. That LMH6624 mentioned is also a real beauty. Though I have to say that the original CLC ones, which were maybe even older than a tlc271, had already almost the same incredible parameters.
Ciao, George
I hate it, but I have to point out that I was looking for cmos opamps..
With low input bias & offset currents and unity gain stability.
This BB one, though is not applicable in the special application discussed here, is a "meraviglia' in itself. A new arrival in that wonderful family of stratosferic amplifiers, which started with comlinear. At our job here these things are having a task. That LMH6624 mentioned is also a real beauty. Though I have to say that the original CLC ones, which were maybe even older than a tlc271, had already almost the same incredible parameters.
Ciao, George
Carlos,
by the way, as I have it at hand, I just can't stand & not show this pic about the way how these things should be applied:
[This is what I would call good low impedance power supply decoupling, up into the hundreds MHz region, ai it is absolutely necessary with such a chip]
Ciao, George
by the way, as I have it at hand, I just can't stand & not show this pic about the way how these things should be applied:
[This is what I would call good low impedance power supply decoupling, up into the hundreds MHz region, ai it is absolutely necessary with such a chip]
Ciao, George
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