• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Subscribers 30 subscribers
  • Views 652 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

AIC3254 Mic noise

Kiran Lall
Intellectual 310 points
Other Parts Discussed in Thread: PGA2505, PCM1861, PCM5142, PCM1863

Hi,


I'm currently designing something around the AIC3254. The input would be fully differential from a dynamic mic (i.e. an SM58 or similar). I'm worried about noise with the PGA's turned up. A few questions.

1)Is there a less costly (but still programmable) alternative to using the PGA2505? I'm looking at the Maxim DS4420

2) If I were to use the PGA2505 as a preamp stage, how would I generate a dual supply (i.e. +15v -15v), given the low voltages involved (i.e. 1.8v/3.3vish from battery)

3) Can something be rigged up (albeit retaining low noise) with an opamp and a digital variable resistor to achieve a similar outcome?

Finally, if I wanted to also use phantom powered condenser mic's with the same circuit, how would I go about generating phantom power?

Thanks

  • 0
    TI__Guru**** 189399 points

    Hi, Kiran,

    I have asked my colleague to comment on your questions about PGA2505.

    Additionally, you might consider using a lower noise A/Ds like our new PCM1861 or one of it's brothers (PCM186x).

    -d2

  • 0 in reply to Don Dapkus
    Intellectual 310 points

    Hi,

    I had a look at the PCM1861 et al, unfortunately the minidsp is key to my design. It's not so much the overall noise noise, more the noise with the PGA's cranked up. I'd say I normally use between +12 and +32db with this sorta mic setup; I'm looking to preserve the dynamic range on the mic.I figure using a lower noise PGA would eliminate at least some of the noise. I'll compare the differences once I've got a prototype in my hands.

    Thanks

  • 0 in reply to Kiran Lall
    Intellectual 310 points

    Having considered your suggestion further I've decided to go with the PCM1863 with a PCM5142 to get the best of both worlds. The minidsp core on the PCM5142 is fine for my application, and the hybrid gain stage on the PCM1863 gives a lot better performance per dollar than I was looking at with other solutions.

    Thanks for your help!