THS4052: Is the unit for RO(output resistance) shown on page 5 of THS4052 datasheet ( SLOS238D) typo?

Kazuya Nakai59

Guru 20785 points

Part Number: THS4052
Other Parts Discussed in Thread: TINA-TI, BUF602, LMH6559

Hello guys,

One of my customers is considering using THS4052 for their new products.

They have the following questions about the device. Copuld you please give me your reply?

Q1. Is the unit for RO(output resistance) shown on page 5 of THS4052 datasheet ( SLOS238D) typo?

Is the correct unit "ohm"?

Q2. When THS4052 is used for a voltage follower as Figure 48 on page 18 of the device datasheet,

is 620 ohm resistor on feedback line in the figure mandatory? Can it not removed?

Q3. They are serching for a high speed operational amplifier can be used for DAC output buffer (voltage

follower) which has very short settling time (about 200~300ns), +/-10V(max) output voltage range, +/-5mA (max) output current and +/-15V power supply range.

If you know any device suited to the above conditions, could you please tell me the TI parts number?

Your reply would be much appreciated.

Best regards,

Kazuya Nakai.

over 5 years ago

0 Michael Steffes over 5 years ago

Guru 48395 points

Oh, you put this in a separate post, please keep your questions on a single design in one post

That 13W is of course an error, very common in those days as the word processes turned the symbol ohm into a W - 13ohms is open open loop. output impedance (which seems pretty low actually).

A lot of good info above, is the DAC generating +/-10V or is this a current output solution to +/-10V.

0 Hasan Babiker31 over 5 years ago

TI__Genius 15555 points

Hello Kazuya,

1) Like Micheal mentioned this is just a typo.

2) The 620 ohm resistor is not mandatory, but will affect the frequency response/phase margin of the device as can be seen in figure 21 of the datasheet shown below:

3) What bandwidth are you looking for in the device?

Best,

Hasan Babiker

0 Hasan Babiker31 over 5 years ago in reply to Hasan Babiker31

TI__Genius 15555 points

Hello Kazuya,

Also in response in the other thread that you opened here: https://e2e.ti.com/support/amplifiers/f/14/p/850693/3146429

I have attached a TINA file for testing the output impedance of the THS4052 spice model. You will see that I have included a plot showing Zout for both RF = 620 & RF = 0 configurations.

THS4052-Zout.TSC

Best,

Hasan Babiker

0 Kazuya Nakai59 over 5 years ago in reply to Hasan Babiker31

Guru 20785 points

Hello Hasan, Michael,

Thank you very much for your reply.

Hasan,

Do you have any high spped OPAMP which has over 1000MHz band width?

Thank you again and best regards,

Kazuya Nakai.

0 Kazuya Nakai59 over 5 years ago in reply to Kazuya Nakai59

Guru 20785 points

Hello Hasan,

I'm sorry. The previous band width was too high. Could you please recommend me any OPAMP which has over 300MHz?

Also could you please tell me how to show Zout curve as the graph you attached?

I ran the TSC file you attached with AC analysis in TINA-TI. But I couldn't display Zout curve in my TINA-TI.

Thank you and best regards,

Kazuya.

0 Michael Steffes over 5 years ago in reply to Kazuya Nakai59

Guru 48395 points

Hello Kazuya, are you looking now for a unity gain buffer with >1Ghz?

0 Kazuya Nakai59 over 5 years ago in reply to Michael Steffes

Guru 20785 points

Hello Michael,

No. I'm looking for a unity gain buffer with >300MHz.

Do you know such TI ope-amp?

Thank you and best regards,

Kazuya.

0 Kazuya Nakai59 over 5 years ago in reply to Kazuya Nakai59

Guru 20785 points

Hello Hasan,

I ran the TSC file you attached with AC analysis in TINA-TI. But I couldn't display Zout curve in my TINA-TI.

Could you please tell me how to display Zout curve and graph?

Thank you and best regards,

Kazuya.

0 Michael Steffes over 5 years ago in reply to Kazuya Nakai59

Guru 48395 points

Sure, the BUF602 is a closed loop buffer (low output Z) exceeding your BW requirements.

There is a much faster buffer in the LMH6559 that is also closed loop, Both show output impedance over frequency plots.

0 Hasan Babiker31 over 5 years ago in reply to Kazuya Nakai59

TI__Genius 15555 points

Hello Kazuya,

You will need to change the y-axis scale to "logarithmic" in order to see Zout in ohms. You can do this by double clicking on the y-axis and selecting the scale drop-down.

Best,

Hasan Babiker

0 Kazuya Nakai59 over 5 years ago in reply to Hasan Babiker31

Guru 20785 points

Hello Hasan,

Thank you very much for your reply.

I could change the Y-axis scale.

Thank you again and best regards,

Kazuya.

Amplifiers

Amplifiers forum

THS4052: Is the unit for RO(output resistance) shown on page 5 of THS4052 datasheet ( SLOS238D) typo?