ELEG 3214 Lecture Notes - Lecture 5: Operational Amplifier, Loop Gain

• School: University of Arkansas
• Department: Electrical Engineering
• Course: ELEG 3214
• Professor: Omar Manasreh

Document Summary

Lec 5 9-2-16 ch2 op amps / weighted summer / non- The weighted-summer circuit still has a resistance rf in the negative- feed(cid:271)a(cid:272)k path, (cid:271)ut (cid:374)o(cid:449) there is a (cid:374)u(cid:373)(cid:271)er of i(cid:374)put sig(cid:374)als (cid:448)(cid:1005), (cid:448)(cid:1006), , (cid:448)(cid:374). Ea(cid:272)h sig(cid:374)al also (cid:272)orrespo(cid:374)ds to a resistor r(cid:1005), r(cid:1006), , r(cid:374). The sig(cid:374)als a(cid:374)d resistors are still connected to the inverting terminal of the op amp. Ohm"s law tells us that the currents are given by. The output voltage is a weighted sum of the input signals . This is why the circuit is called a weighted summer. With this weighted summer all the signal coeffecients must be of the same signal. Sometimes it is necessary to sum signals with opposite signs. This can be done using two op amps as shown below. If we let the first op amp handle the negative sign signals and the second op amp handle the positive sign signals then the process to find goes as such.