For low closed loop gain and high band width frequency compensation is used in op-amp
There are two types of frequency compensation techniques they are:
- Internal frequency compensation technique.
- External frequency compensation technique.
Internal Frequency Compensation Technique :
- It makes use of internal components for compensation.
- Usually used in instrumentation amplifiers.
- Also called as internally compensated op-amp.
- IC741 contains capacitance C_1 = 30pf which internally shunts off signal current and thus reduces available out put signal at higher frequency.
- The internal capacitance C1= 30pf the compensating element which causes open loop-gain to roll off at -20dB/decade rate and gives a stable circuit.
- Bandwidth product of op-amp is 1mHz and if IC741 is wired for a closed loop gain of 104/80dB then its bandwidth is 100hz for a gain of 102 bandwidth. The bandwidth increase to 10KHz with gain one making bandwidth 1Mhz.
External Frequency Compensation Technique :
These circuit fuse external frequency components to give low closed loop gain. The two common methods are:
- Dominant pole compensation.
- Pole zero compensation.