Read front end of a new AC coupled preamplifier for 300 Mb/s hard disk drives using single stripe magneto resistive heads

This paper describes the read front end structure of a new current bias voltage sense low noise preamplifier designed for Hard Disk Drive applications working at 300 Mbit/s and using single stripe M.R. heads. The use of AC coupling capacitors together with a gyrator enables to separate the M.R. head biasing circuit from the fully symmetrical amplifier. Common mode signal is then treated as interference and rejected by the amplifier even at high frequencies. CMRR and supply rejections higher than 45 dB up to 200 MHz has been demonstrated.