OPA462: Howland Current Source

Hello,

This device is bandwidth restricted at +/-50V to 50kHz (see figure below). This means that we can start to see distortion close to 100kHz. As you are also gaining up the circuit, this further restricts the bandwidth (BW = Gain Bandwidth / Gain).

I have attached a simulation of a Howland Current Pump that seems to work fairly well at 100kHz, but you can see that there is some ringing on Vset. Is there a set load for this application, or is it varying? 

OPA462 Howland 10 mA Ipump100khz.TSC

Best regards,
Carrie

Hi, thank you for your reply. However, I see that you’re using a square input signal of ±3 V, while unfortunately I can only use a sinusoidal signal of ±1.65 V. For this application, the load will be fixed.

Hi Matej,

Thank you for the information. I simulated the circuit again with your design parameters, and it seems to be fairly stable without distortion. Below is the circuit setup, and outputs at 50kHz, 75kHz, and 100kHz. I have RL = 1k, but let me know if that value needs to change. Please look it over and let me know of any concerns.

Thank you,
Carrie

5327.OPA462 Howland 10 mA Ipump100khz.TSC

Thank you, I also arrived at something like this, but unfortunately I wasn’t able to get it to work for higher resistances up to those 4800 Ω. I would also be interested in how you arrived at those resistor values, and whether it would be possible to send the calculations, please. Thank you