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LMV1091 LPF

Other Parts Discussed in Thread: LMV1091

Hi

I understand that it is possible to low pass filter the output.

This low-pass filter is created by connecting a capacitor between the LPF pin and the OUT pin of the LMV1091. In the datasheet there is also a table (table 6) with values for the capacitor and resistor. Where is the resitor placed? In series with the capacitor? In parallel?

The evalution board for the EVM1091 comes with a 1000pF capacitor fitted. Where would I place this resitor?

Any help greatly appreciated.

Paulo

  • Paulo,

    The resistor is internal to the device.  It is the gain setting feedback resistor you can see in Figure 1 across the output amplifiers.  When you change the gain, the value of the feedback resistor changes.  Table 6 gives you the resistance for the 5 different gain settings, and the capacitance to achieve a 2kHz rolloff.  Choose your desired gain, then use the Rf value from table 6 to calculate the capacitance to meet your desired LPF roll off.

    Regards,

    royce