A high speed low noise CMOS MR preamplifier for disk drives

In this paper we present design for a high speed low noise preamplifier for use with magnetoresistive read elements in disk drive channels. The performance of the reader circuit is comparable with the more expensive current generation of BiCMOS MR preamplifiers. The measured results include a gain of 43dB, 3dB bandwidth of 273MHz, input-referred voltage noise is less than 0.57nV/√Hz, and input-referred current noise is less than 0.8pA/√Hz. The preamplifier has been implemented in a 0.8-µm CMOS process and occupies a die area of 1.78 × 1.78 mm².