Low Noise Transistors: Comparing the ZTX1053A and ZDT1053 (Dual) vs. the ZTX689B and ZTX851

Where we discuss new analog design ideas for Pro Audio and modern spins on vintage ones.
User avatar
mediatechnology
Posts: 4276
Joined: Sat Aug 11, 2007 2:34 pm
Location: Oak Cliff, Texas
Contact:

Low Noise Transistors: Comparing the ZTX1053A and ZDT1053 (Dual) vs. the ZTX689B and ZTX851

Post by mediatechnology » Tue Mar 10, 2020 3:15 pm

I was looking for a dual low noise transistor in the Zetex line and came across the ZDT1053 dual and it's through-hole single the ZTX1053.

I decided to compare the ZTX851, ZTX689B and ZTX1053 in through hole before I test the ZTD1053.

I setup a simple test circuit similar to the one here:

Image

In order to maximize the transistor's noise contribution I made Rsource and Rgain 1Ω.
Rfb is 316Ω.
Gain = 61.6 dB
Ic is about 7.5 mA.

Here are the results in this circuit:

ZTX851 Ein -143 dBu Rnv 9.4Ω Noise Density 390 pV√Hz.
ZTX689B Ein -137.9 dBu Rnv 30Ω Noise Density 695 pV√Hz.
ZTX1053 Ein -139.9 dBu Rnv 19Ω Noise Density 553 pV√Hz.

The ZTX1053 looks ideal for mic preamps.
hFE for the ZTX1053 I tested ranged from 300-500 at low test currents.
Cobo is also low-ish around 21 pF.

With the ZTX1053 single looking so promising I'll be checking the dual ZDT1053.
I bought 6 - the Vos spread of the pairs was <<500 µV on all 6.
https://ka-electronics.com

"Planned Parenthood Admission In Deposition Regarding Fetal Organ Sales" https://proaudiodesignforum.com/content ... ission.mp4
"Plandemic/Doctors In Black" https://proaudiodesignforum.com/content/Plandemic.mp4

User avatar
JR.
Posts: 3277
Joined: Sat May 24, 2008 7:21 pm
Contact:

Re: Low Noise Transistors: The ZTX1053A and ZDT1053A (Dual) vs. the ZTX689B and ZTX851

Post by JR. » Tue Mar 10, 2020 3:50 pm

Nice .... put some of these in the time capsule to send back to 1975.... :lol:

JR
Don't only half-ass tune your drums. Visit https://circularscience.com to hear what properly "cleared" drums sound like.

User avatar
mediatechnology
Posts: 4276
Joined: Sat Aug 11, 2007 2:34 pm
Location: Oak Cliff, Texas
Contact:

Re: Low Noise Transistors: The ZTX1053A and ZDT1053A (Dual) vs. the ZTX689B and ZTX851

Post by mediatechnology » Tue Mar 10, 2020 4:31 pm

JR. wrote:
Tue Mar 10, 2020 3:50 pm
Nice .... put some of these in the time capsule to send back to 1975.... :lol:

JR
I'll leave some in my basement. :lol:

A visual comparison:

Image
ZTX Low Noise Transistor Comparison ZTX689B (top) ZTX851 ZTX1053A (middle) ZTX851 (bottom)

ZTX689B Ein -137.9 dBu Rnv 30Ω Noise Density 695 pV√Hz.
ZTX1053 Ein -139.9 dBu Rnv 19Ω Noise Density 553 pV√Hz.
ZTX851 Ein -143 dBu Rnv 9.4Ω Noise Density 390 pV√Hz.

Zetex Low Noise NPN Datasheets:

ZTX689B: https://proaudiodesignforum.com/images/pdf/ZTX689B.pdf
ZTX851: https://proaudiodesignforum.com/images/pdf/ZTX851.pdf
ZTX1053: https://proaudiodesignforum.com/images/pdf/ZTX1053A.pdf
ZDT1053 Dual: https://proaudiodesignforum.com/images/pdf/ZDT1053.pdf
https://ka-electronics.com

"Planned Parenthood Admission In Deposition Regarding Fetal Organ Sales" https://proaudiodesignforum.com/content ... ission.mp4
"Plandemic/Doctors In Black" https://proaudiodesignforum.com/content/Plandemic.mp4

terkio
Posts: 186
Joined: Thu Feb 07, 2019 4:17 am

Re: Low Noise Transistors: The ZTX1053A and ZDT1053A (Dual) vs. the ZTX689B and ZTX851

Post by terkio » Tue Mar 10, 2020 4:34 pm

Great.

From the ZTD1053TA datasheet.
There is no information about transistor matching.

Foot notes at thermal characteristics, indicate the two transistors are on separate dies.
It is not clear wether we are better with a dual ZTD1053 rather than with two singles ZTX1053 we can match.

The case is plastic, most heat dissipates via the collector leads.
Temperatures of the PCB tracks at the collectors are the key factors about junction temperatures hence V be matching.

User avatar
mediatechnology
Posts: 4276
Joined: Sat Aug 11, 2007 2:34 pm
Location: Oak Cliff, Texas
Contact:

Re: Low Noise Transistors: Comparing the ZTX1053A and ZDT1053 (Dual) vs. the ZTX689B and ZTX851

Post by mediatechnology » Tue Mar 10, 2020 4:42 pm

My thought was the dual SMT could have a metal slug glued onto it to equalize the temperatures (and add thermal mass) as well as a PCB pour under it.
https://ka-electronics.com

"Planned Parenthood Admission In Deposition Regarding Fetal Organ Sales" https://proaudiodesignforum.com/content ... ission.mp4
"Plandemic/Doctors In Black" https://proaudiodesignforum.com/content/Plandemic.mp4

User avatar
mediatechnology
Posts: 4276
Joined: Sat Aug 11, 2007 2:34 pm
Location: Oak Cliff, Texas
Contact:

Re: Low Noise Transistors: Comparing the ZTX1053A and ZDT1053 (Dual) vs. the ZTX689B and ZTX851

Post by mediatechnology » Tue Mar 10, 2020 4:50 pm

There may be some Zetex duals that share a common die.
We may have quite a few devices Zetex designed for low Vce saturation which are also low noise.
https://ka-electronics.com

"Planned Parenthood Admission In Deposition Regarding Fetal Organ Sales" https://proaudiodesignforum.com/content ... ission.mp4
"Plandemic/Doctors In Black" https://proaudiodesignforum.com/content/Plandemic.mp4

terkio
Posts: 186
Joined: Thu Feb 07, 2019 4:17 am

Re: Low Noise Transistors: Comparing the ZTX1053A and ZDT1053 (Dual) vs. the ZTX689B and ZTX851

Post by terkio » Wed Mar 11, 2020 4:59 am

mediatechnology wrote:
Tue Mar 10, 2020 4:42 pm
My thought was the dual SMT could have a metal slug glued onto it to equalize the temperatures (and add thermal mass) as well as a PCB pour under it.
What do you mean by a PCB pour under it ? Some thermal pad.

I was struck by the thermal resistances mentioned in the ZTD1053 datasheet.
The Rth from junction to collector leads: 30 K/W
The Rth from junction to ambient: 50 K/W
I imagine the junction heat mostly dissipate via the collector leads, this is why there are two pins for each collector. Some heat dissipate to ambient by the case, but much less than by the collector pins.
I understand, they count on the collector tracks to act as heatsinks. They better have equal thermal resistance to ambient. Same area same air flow.
Plus as an improvement to a best thermal equalization, a thermal bridge between the collector tracks should be good to have. Hence adding some PCB thermal pad under the chip.
[Edited]
Heath sinking by the PCB tracks.
From the data sheet I understand:
25mm x 25mm 2 oz copper at each collector pin pairs. That is quite a lot of PCB real estate for a tiny SMD circuit 6mm x 7mm. I wonder about the layout. May be the SMD on a piggy back circuit ?
[/Edited]

User avatar
mediatechnology
Posts: 4276
Joined: Sat Aug 11, 2007 2:34 pm
Location: Oak Cliff, Texas
Contact:

Re: Low Noise Transistors: Comparing the ZTX1053A and ZDT1053 (Dual) vs. the ZTX689B and ZTX851

Post by mediatechnology » Sun Mar 15, 2020 8:06 am

I was visualizing a thermal pad.

The Vos may be purely the luck of the draw with two separate die.
Of the 6 I tested all would have been usable in terms of Vos. (delta-Vbe.)

We don't need the big thermal areas since we're not switching amps of collector current.
https://ka-electronics.com

"Planned Parenthood Admission In Deposition Regarding Fetal Organ Sales" https://proaudiodesignforum.com/content ... ission.mp4
"Plandemic/Doctors In Black" https://proaudiodesignforum.com/content/Plandemic.mp4

User avatar
mediatechnology
Posts: 4276
Joined: Sat Aug 11, 2007 2:34 pm
Location: Oak Cliff, Texas
Contact:

Re: Low Noise PNP Transistors: Comparing the 2SB737 to the ZTX951

Post by mediatechnology » Mon Mar 16, 2020 3:13 pm

I got bored and decided to measure some low noise PNP transistors by inverting the polarity of the test circuit.

The top trace is the 2SB737; the bottom trace the ZTX951.

Image
Low noise transistor comparison: The 2SB737 (top) versus the ZTX951 (bottom).

The PNP ZTX951 is about 0.4 dB quieter than the NPN ZTX851.

The 2SB737 is 3-4dB quieter than the high gain ZTX689B and ZTX1053A NPNs so, for low impedance sources, the 2SB737 remains the best choice when high hFE is needed.
https://ka-electronics.com

"Planned Parenthood Admission In Deposition Regarding Fetal Organ Sales" https://proaudiodesignforum.com/content ... ission.mp4
"Plandemic/Doctors In Black" https://proaudiodesignforum.com/content/Plandemic.mp4

terkio
Posts: 186
Joined: Thu Feb 07, 2019 4:17 am

Re: Low Noise Transistors: Comparing the ZTX1053A and ZDT1053 (Dual) vs. the ZTX689B and ZTX851

Post by terkio » Tue Mar 17, 2020 10:07 am

2SB737 has become unobtainium.
No hit on octopart.
High prices on unreliable sources, risk of fakes.

With low cost in mind. ZTX1053 or ZTD1053 paralleling can give a lowest noise and better Vbe Hfe matching.

Post Reply