Question

(c) (d) 7. Howland current source. [7 pts. The op-amp circuit shown is a Howland current source or current pump. R, at loadn provided that 3 R R2 R Show that os n provided that Note: despite the apparent cleverness of this current source, several issues preclude its widespread application, e.g., the resistors must be exactly matched or the circuit deviates from the result derived above. Additionally, performance is limited by the common-mode rejection ratio of the op-amp, the resistors must be kept small for large currents -limiting compliance, and at high frequencies the output impedance drops from the desired infinite value (remember current sources want high output impedance) to several hundred ohms. -- w Г

Answer 1

gi vo Iage vlua hn andohverhn noden are esual ηση る ke at node. U-Vin R4 -Vin Rt

R2 , R3 , 근L 以-R R3 늪- Jin ZL R3 t R 小 1load R3 Ri