Frequency-Domain Analysis of Effects of the Location of a Feedback Resistor in a Current Feedback Amplifier

A current feedback amplifier (CFA) has good high-speed properties but its performance is very dependent on interconnect designs, particularly its feedback interconnect design. In this brief, effects of the location of a feedback resistor in the feedback interconnect design of a CFA are analyzed in the frequency domain. A transfer function of a CFA is derived, and frequency responses are simulated by varying the location of a feedback resistor in the transfer function. Then, experiments are carried out with test circuits consisting of CFAs with diverse locations. It can be seen that further distance of the resistor to the inverting input of the CFA results in larger distortion of the CFA's frequency response. This result is true even if the total length of the feedback interconnect is constant.