THS4531A: Can I use THS4531A to attenuate the output of AMC1210?

Hi Jimmy,

the AMC1210? This chip has no analog output. Please correct this typo and give more details on your application (attenuation factor, bandwidth, etc.)

In any case you will need a low pass filter behind the AMCxxxx to remove its chopping noise. This can be implemented in the fully differential amplifier (FDA). The typical charge bucket filter needed at the input of ADC may not be needed here because the ADBT1001 seems to have an input buffer. But the noise performance can profit from such a charge bucket filter.

You may also want to read these threads:

https://e2e.ti.com/support/amplifiers-group/amplifiers/f/amplifiers-forum/984716/ths4531a-stability-and-gain-1

https://e2e.ti.com/support/amplifiers-group/amplifiers/f/amplifiers-forum/815166/ths4531a-ths4531a

Kai

Hi Kai,

Sorry, It is AMC1202.  The PWM frequence is 500KHz. 

G= reduce 41. due to AMC1202 fix gain is 41 and use THS4531 attenuate 41 then into ADBT1001. 

So I want to know which solution is better. thx 

Hi Jimmy,

the bandwidth of AMC1202 is only 280kHz according to the datasheet which is a too low for a PWM frequency of 500kHz.

Kai

Hi Kai,

It's fine. the PWM frequency from ADBP1001 controller. I just measure the output current. I think the current is DC.

So Which fully differential OP is better for me?

Hello Jimmy,

   Do you need a 1/41 V/V attenuator? 

   If so, using the THS4531A you might achieve around 600-700kHz of bandwidth. I would suggest switching over to the THS4551 with a GBW of 135MHz. 

   Section 10.1.6 on page 45 of the THS4551 datasheet goes through the steps on designing an attenuator including the calculation of the compensation capacitors. 

Thank you,
Sima

Hi SimaJalaleddine,

Yes, I need a 1/41 V/V attenuator. 

thanks for your great support.