• AD8638或AD8639的输入噪声电流问题

    为什么在AD8638或者AD8639的芯片手册上没有输入噪声电流这一个指标?谁知道这个指标的值是多少?

  • 用来搭建零阻电流计,用AD8638是否合适呢?

    用运放搭建零阻电流计,用来测量微安级电流,用AD8638是否合适呢?或者是否还有比它更适合的芯片?

  • AD8638构成的零电阻电流计,正负输入调换后,测得的电流值不同。

    电路如下图,AD8638构成的零电阻电流计,理论上说输入的接口反向后,应该测得的电流值是一样的,只是方向相反。

    但是实际测量时发现,电流大约为190uA左右,下面电流测得的正值为191uA,而反相后仅为-152uA。

    所以这是这个电路结构的原因吗?

    还是芯片的原因?

  • RE: HMC6981

    Hi Jac,

                AD8638 is the Op amp we recommend using. The resistor values have been updated please see attached document for the latest circuit.

    Regards,

    Jim B

     PDF

  • RE: AD5791 operate voltage

    Hi Rainier

    Thank you for your suggestion.

    another question about AD5791 ( 20 bit DAC )  &  AD5541A ( 16 bit  DAC ) 

    Which spec is concerned about replace the  uni-gain buffer ( AD8638 or AD8639 )  to AD8675 ?

    Since the Input offset voltage for AD8638 is 3…

  • RE: What is the Common mode voltage range of ADA4522-2 ?

    Hi Emman,

    It is functioning well but as temperature changes the drift of output current is also large. So i was looking for an IC which had low offset voltage and drift. Then i came across AD8638, AD4522-2 etc. One doubt which i have is that, in the…

  • RE: Issue with search for ADA range

    FormerMember
    FormerMember

    Riscy,

      Take a look at the AD8638/8639.

    Harry

  • ADA4638: FAQs Temperature sensing Using Zero Drift Op Amps

    Q.

    I am looking for an op amp to signal condition a low frequency (<100Hz) temperature sensor. I need a high precision amplifier with good offset voltage and drift. What are the appropriate amplifiers that you recommend?

    --------------------------…

  • RE: AD8639 as AC Preamplifier for Thermopile?

    Hi Laxman,

    If you take a closer look, the first amplifier on that configuration has a gain of 1000. This would greatly amplify any DC errors on the inputs of the amplifier, including the low offset voltage of the AD8638 from 3uV to almost 3mV. The 10uF…

  • RE: AD8231 op-amp bandwidth and part number

    FormerMember
    FormerMember

    Bruce,

    You didn't say what the corner is, etc.  Did you use the Filter Wizard to design the HPF?

    What do you mean by LP resonse?

    Can you attach schematic and also freq response plot?

    The op amp in the AD8231 doesn't have a part number;  it…