CFA & its applications

Q.  The applications provided by CFAs are limited to bipolar transistor because they do not exhibit the necessity of ______
- Published on 24 Sep 15

a. Low input impedance
b. High input impedance
c. Both a and b
d. None of the above

ANSWER: High input impedance
 

    Discussion

  • Satyawati Patil   -Posted on 09 Oct 15
    Current feedback amplifiers (CFAs) uses trans-impedance instead of gain. The configuration of CFA in which the input current is mirrored to the output stage and buffered by an output buffer provides highest bandwidth.

    CFAs are limited to bipolar transistors because the applications served by them does not require high input impedance or rail-to-rail output voltage swing. These applications are mainly concerned to communication and video aspects.

    Since the inverting input lead looks into the output of buffer, it possesses low input impedance. On the contrary, non-inverting lead looks into the buffer input & hence it has high impedance.

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