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opa2349: Gain bandwidth product at 1.8Vdc

Part Number: OPA2349

I have an application which is attempting to use the opa2349 up to about 4Khz.  My gain is relatively low: around 8, but it seems that the output is rolling off faster than I would have expected. 

We need the very low quiescent current otherwise wise I'd use other devices. 

Specifically have an about a 10mv pp signal AC coupled to the amplifier in a non-inverting configuration. I have the biased the + input at mid-rail  (0.9V) 

The datasheet characterizes the opa2349 at 5.5 volts.  Is there any data for the device at the lower voltages?  

I have a TINA schematic but I'm new to TINA and find it very difficult to use compared to other simulators so the simulation does not give me results that even come close to what I'm seeing in the real circuit. (A competitors simulation tool using a device with similar characteristics but higher operating current does work and is closer to what I expect. It does not show the roll off even even through it has a lower bandwidth) 

TinaOpa2349 simulation.TSC

  • Hello William,

    I checked the original OPA2349 archive and did not find any characterization information specific to 1.8 V operation. That isn't too surprising because the operating current changes a small amount across that supply range. The QUIESCENT AND SHORT-CIRCUIT vs SUPPLY VOLTAGE graph on page 6 of the datasheet shows that the quiescent current (Iq) changes just a little over 10% over that supply range. The ac characteristics are the op amp usually track to some extent the Iq current for a CMOS op amp of this type. Therefore, we wouldn't expect the bandwidth to change by anymore than that percentage.

    There were some problem with you TINA simulation circuit setup. Most notably the power supply connections to the op amp were reversed and that would have prevented a correct simulation. I corrected the connections and ran a dc operating current sweep and compared the amplitude vs frequency response for a supply range of 1.8 V to 5.5 V. The Iq vs supply changed about 15% for the model over the supply range, and the circuit bandwidth was identical for the two supply extremes. 

    The TINA file has been included should you need to run more simulations.

    Regards, Thomas

    Precision Amplifiers Applications Engineering

    Opa2349 sim_01.TSC