1
\$\begingroup\$

I have this circuit that converts a single ended input signal to differential output signal. I want to understand how to calculate or find out its input and output impedances?

The two op-amps are in inverting and non-inverting configuration. Will this circuit work correctly as single to differential mode converter or should both of the op-amps be in the same configuration?

Circuit diagram

\$\endgroup\$
  • \$\begingroup\$ what range of frequencies must you handle? \$\endgroup\$ – analogsystemsrf Nov 18 '19 at 15:06
1
\$\begingroup\$

It depends on what you're driving the circuit with. Your noninverting arm has infinite input impedance, and your inverting arm has relatively small input impedance. This could be problematic, but not in every situation. For example, if your input is some sort of piezo-device, you will be very unhappy.

The input impedance of the inverting input is \$330R \parallel 660R\$. The output impedances are small, approximately \$33R\$ on each branch.

| improve this answer | |
\$\endgroup\$
  • \$\begingroup\$ How can we do it with both non-inverting arms? \$\endgroup\$ – alt-rose Nov 18 '19 at 13:50
  • 1
    \$\begingroup\$ For one, you can use a voltage follower to buffer \$V_{\text{in}}\$ \$\endgroup\$ – Scott Seidman Nov 18 '19 at 13:54
  • 1
    \$\begingroup\$ You need at least one stage that INVERTS. \$\endgroup\$ – analogsystemsrf Nov 18 '19 at 15:37
  • 1
    \$\begingroup\$ @analogsystemsrf after you buffer Vin, it doesn't make as much difference what happens. A voltage follower on the far left wire fixes most ills. \$\endgroup\$ – Scott Seidman Nov 18 '19 at 15:55

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.