Low noise AC coupled amplifier with low band-pass corner and low power

摘要

A low noise AC coupled amplifier having transistors sharing bias currents, and having a low band-pass corner frequency and consuming low power. The amplifier may be used in a magneto-resistive (MR) preamplifier to amplify a response from a MR sensor. Bipolar and MOS transistors are used in the front end, utilizing the advantages of each transistor type to achieve low noise as well as low band-pass corner. The amplifier has a modified structure achieving lower power by using a PNP transistor instead of an NPN transistor.