The latest application principle circuit of CFB amplifier

　　Current feedback (CFB) amplifiers mostly belong to the category of high-speed amplifiers. A number of good application guides have been published in recent years that describe the operation of current feedback amplifiers and the main problems encountered therein. Here we will summarize it in a short text.

　　The CFB amplifier has a high impedance input (non-inverting input), a low impedance input (inverting input), and an output low impedance as shown in the figure below. As long as the input is not loaded, the voltage at the non-inverting input terminal will see high input impedance. The voltage at the non-inverting input appears at the inverting input as it passes through the buffer . Since the buffer is less than ideal, it will have a gain a(s) that changes with frequency, and the DC amplitude is very close to 1V/V, typically 0.996V/V. In addition, the output impedance of the buffer in the ideal case is 0W. In practice, the output impedance ranges from a few ohms to tens of ohms.