A Simple Calculation Method for the Gain of Universal Two Order Filter on OTA's

Taking calculation of the gain of universal two order filter on OTA's as example,an open-loop method was extended to the system with multiple feedback paths. It is pointed out that when a loop path is cut off,the rest of the circuit is regarded as to have no feedback,and the loop gain and forward channel gain can be calculated,and the closed loop gain can also be calculated basing on the basic equation of feedback circuit.It is stressed that the loop gain and forward channel gain change with the loop path cut off,but the closed loop gain remains unchanges.If cutting off point cuts all loop paths off,the loop gain and forward channel gain can be calculated simply.Thus we can simplify the method of calculating the closed loop gain.In a word,we can calculate the gain of high order filter in short time by extended open-loop method,which is suitable to popularize.