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DRV134: Reducing gain of DRV134

Brian Josephs
Prodigy 90 points
Part Number: DRV134
Other Parts Discussed in Thread: INA134, PGA2311

Hello,

I'm designing a preamp around the PGA2311 and I'm using the DRV134 and INA134 chips to facilitate balanced I/O.   I want to maintain the largest signal swing I can within the PGA to keep the THD low but the added 6db of gain from the DRV134 is going to cause clipping with the low +/-5vDC rails I'm running the audio section from.  I need to pad down the output of the PGA before entering the DRV to maintain unity gain.  Since the front end of the DRV is an inverting opamp with 30k resistors can I just put an additional 30k in series to reduce the first stage gain to 1/2?  The data sheet says to drive from a low source impedance but doesn't specify what parameters would suffer.  If this is unwise I'll use a small resistive divider instead.

Brian

  • 0
    TI__Guru* 98965 points
    Hi Brian,

    Using series resistor at the input of DRV134 would reduce the gain at the output of the device. However this would be a trade off. Too high impedance at the input could let higher noise to couple into the signal path. The lower the source impedance the better the noise immunity.
    You can do some testing to see if the performance is good for your application.

    Best regards,
    -Ivan Salazar
    Audio Applications Engineer - Low Power Audio & Actuators