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TLV3541: Wien Bridge oscillator

Kai Nomiyama
Expert 5285 points
Part Number: TLV3541
Other Parts Discussed in Thread: TINA-TI, , OPA863, OPA810

Hi Team,

I'm looking for oscillator solution that meets following requirement.

Vdd: 5V

freq: 400kHz ~ 1MHz (no adjustable requirement)

Vout_pp: 3~5V

low distortion.

I created wein bridge in TINA-TI referring below e2e.

https://e2e.ti.com/support/amplifiers-group/amplifiers/f/amplifiers-forum/1020764/tlv2471-3mhz-wien-bridge-sine-wave-oscillator?tisearch=e2e-sitesearch&keymatch=%22wien%20bridge%22#

Wien_bridge.TSC

The design challenge is difficult to meet Vout_pp: 3~5V even if using dual channel opamp since startup voltage is higher than stable voltage.

if we use two single opamp and control the second opamp powerup sequence, it seems we can meet Vout_pp.

Anyway, question is

- I pick up TLV3541 but are there any recommended opamp?

- please modify the schematic if there are anything wrong?

- Are there any way to meet Vout_pp 3~5V with dual opamp?

Regards,

Kai

  • 0
    TI__Mastermind 22390 points

    Hello Kai,

      Can they use a higher power supply voltage range, and are they limited to a single supply rail? Do they need a dual channel amplifier, or they chose this option because they wanted to meet the output voltage requirement of 3 to 5V? 

       For a max frequency of 1MHz at 5V, I would recommend an amplifier with a GBW of at least 10MHz, and around 50V/us of slew rate. From the app note on sine wave oscillators, it suggests picking an amplifier with a bandwidth of around one decade above cutoff frequency of the oscillator. 

       

       From above results, it looks like an amplifier with bandwidths closer to this bandwidth estimations result in better overall distortion. So you might find better options in precision amplifier if DC precision is important, or in general purpose amplifiers. 

      But, from sims, TLV3541 seems like a good choice, and the schematic + values look good. Here is another app note by Ron explaining the details in how these values were chosen. I would also suggest OPA863 or OPA810, both are available in dual channel packages, have a higher voltage rail range, and are RRIO. 

    Thank you,
    Sima