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LMH6518: LMH6518 o/p voltage swing

1567623
Intellectual 330 points
Part Number: LMH6518
Other Parts Discussed in Thread: LMH6881

Hi

Currently  using VGA as LMH6518 (below is the circuit for the same). The output of this is given as the input for the ADC LTC2191.

As per datasheet the maximum output swing at the VGA out is 0.8Vpp only. Please confirm the below queries.

1)       whether it can have output voltage swing of 0V to +2V.

2)      Or do we have to change the PGA to LMH6881.

3)      Can it be interfaced withLTC2191 ADC directly after the coupling specified in the ADC datasheet

 

 

 

  • 0
    TI__Expert 7875 points
    Hi,

    You are correct that the LMH6518 can only output 0.8 Vpp. differentially. It will not be able to support an output swing of 0 to +2V. The LMH6881 provides a maximum of 6 Vpp which is more than the ADC needs and will allow enough swing to add a matched filter between the amplifier and ADC if desired. The ADC datasheet shows an AC coupled interface with the fully differential amplifier, however the amplifiers can be used DC coupled if desired. If using the DC coupling, the amplifier will need a negative voltage supply generated so that the output can successfully swing to 0V.

    Regards,