Question

Which of the following feedback type is employed with DC amplifiers?

(a) negative

(b) can be any positive or negative doesn’t matter

(c) depends on the application

(d) positive

This question was posed to me in an interview for job.

The origin of the question is Single Channel Telemetry System topic in section Biomedical Telemetry of Biomedical Instrumentation

Answer 1

Right answer is (a) negative

Explanation: DC amplifiers are generally of the negative feedback type. They are used for medium gain applications down to about 1 mV signal levels for full scale. They are not practical for very low level applications because of dc drift and poor common-mode rejection capabilities.