High impedance low noise cross-coupled amplifier for use in as a preamplifier in a magnetic data storage system

摘要

A balanced amplifier with a relatively high input impedance with wide bandwidth for use as a fly-height sensor head preamplifier in a magnetic storage read system. The balanced amplifier has two substantially identical halves, each amplifier half having an input transistor, responsive to the input node of the amplifier half disposed in series with a cross-coupling transistor receiving a buffered cross-coupled version of the input signal applied to the other half of the balanced amplifier. Use of cascoded transistors and voltage-followers to limit voltages across various the input and cross-coupling transistors enhance the common mode rejection and power supply rejection ratios of the amplifier while retaining a low high-frequency noise figure similar to low-input impedance balanced amplifier designs.