• State TI Thinks Resolved
  • Locked Locked
  • Replies 1 reply
  • Answers 1 answer
  • Subscribers 47 subscribers
  • Views 754 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

Medical current source

user4646208
Intellectual 580 points


I want to make a device for medical purposes.

I need a PWM on the frequency of 100kHz currents within ± 0.05mA ~ 2mA with the ability to adjust it using a DAC.

Electrodes are connected to the ear of the patient, I tried to create a skin model:

I have three schemes but they all work not as I would like.
I need to get the best possible signal shape without overshooting and ringing.
What can I change to get the best result? Maybe I should use other op-amp?

1)

2)

3)

  • 0
    TI__Genius 16080 points

    Hi user4646208,

    This may be a difficult circuit to stabilize properly, due to the complex load impedance you're driving. While the Howland Current Pump you're using should be stable into capacitive loads, it will have difficulty with inductive loads.

    We've released a series of presentations here which cover techniques to analyze circuit stability within SPICE. Note that these techniques do require the op amp's SPICE model to accurately simulate open-loop output impedance and open loop gain/phase.