Guzik Technical Enterprises

Serguei Pantchenko

Anatoli B Stein

A spectrum analyzer with a compensation circuitry for prevention of measurement accuracy deterioration due to local oscillators phase noise.

Spectrum analyzer with phase noise compensation

A read amplifier system for connection through interconnects to a magnetoresistive (MR) head includes two input transistors, two bias transistors connected to the two input transistors by common source connections, a bias voltage control circuit connected to base terminals of the two bias transistors, a common mode voltage control circuit connected between first and base terminals of the input transistors to provide feedback from the first terminals to the base terminals, and a compensating circuit connected between the outputs of the amplifier system and the base terminals of the input transistors for providing a feedback from the outputs to the base terminals. The two base terminals of the input transistors are respectively connected to the interconnects of the MR head. The bias voltage control circuit applies a bias voltage to base terminals of the two bias transistors, and through the common sources to the base terminals of the input transistors, and thereby across the MR head. An input signal representing changes in resistance of the MR head is transmitted from the MR head to the input transistors and is amplified by the read amplifier system.

Low impedance read amplifier for magnetoresistive head

An apparatus for substantially eliminating a switching voltage transient in a magnetic recording system so as to minimize a write-to-read recovery time includes a first bias enable switch, a bias current source responsive to the first bias enable switch, an MR sensor for receiving a bias current from the current source, and a read amplifier being capacitively coupled to the MR sensor. The bias current flowing through the MR sensor produces the switching voltage transient due to the RC time constant presented by the input of the read amplifier. The apparatus includes a first compensating circuit for generating a compensating voltage transient having a polarity substantially equal and opposite to the switching transient. The first compensating circuit is electrically coupled to the MR sensor, and a superposition of the switching voltage transient and the compensating voltage transient is substantially zero.

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Scotts Valley, CA, United States of America

Serguei Pantchenko