内部输入偏置电流消除 Internal Input Bias Current Cancellation Bruce Trump Last week we reviewed the use of an input bias current cancellation resistor to balance the source resistance at the two inputs of an op amp. The conclusion was that this practice is often not necessary and may even be detrimental. This discussion builds on the previous blog so you may want to review it, first. [pic] I ended last week saying that there are certain op amps for which this practice is definitely not recommended. These are amplifiers with bipolar input transistors (BJTs) that have internal input bias current cancellation. They have current sources, I1 and I2 that supply base current for the input transistor pair. These currents are derived by mirroring carefully matched base cur……