公开(公告)号：JP2000100075A

公开(公告)日：2000-04-07

申请号：JP23385299

申请日：1999-08-20

Applicant: IBM

Inventor： PHILPOTT RICK ALLEN ,  GREGORY SCOTT WINN

IPC: G11B7/09 ,  G11B5/00 ,  G11B5/39 ,  G11B5/455 ,  G11B19/04 ,  G11B20/10 ,  G11B27/36

Abstract: PROBLEM TO BE SOLVED: To provide a system and method for deciding the amplitude of a read back signal to be acquired from a data storage medium. SOLUTION: These system and method for measuring the amplitude of the read back signal to be acquired from the data storage medium include preferably a step to transmit the read back signal to a gain changeable amplifier such as a variable gain amplifier(VGA) 76 provided inside a read out channel. Voltage signals relevant to a loop gain of an amplifier circuit are sensed and compared with many control voltage signals relevant to corresponding digital word values. The digital word value relevant to the control voltage signal equal to the sensed voltage signal shows the relative amplitude of the read back signal. Further, a gain characterizing circuit is combined to a circuit for measuring the read back signal amplitude preferably in the read out channel, then the absolute amplitude of the read back signal is acquired.

公开(公告)号：JPH10233639A

公开(公告)日：1998-09-02

申请号：JP2476698

申请日：1998-02-05

Applicant: IBM

Inventor： GREGORY SCOTT WINN ,  RAYMOND ALLAN RICHIETTA

IPC: H03G3/02 ,  H03F1/30 ,  H03F1/32 ,  H03G1/04

Abstract: PROBLEM TO BE SOLVED: To optimize the SNR of an input swing, and to minimize distortion over the entire range of an operation temperature by using a variable gain circuit controlled by the control signals of a temperature control circuit and controlling the signal swing of input signals so as to fluctuate along with temperature fluctuation within the effective linear signal range of an analog circuit. SOLUTION: Through the variable gain circuit 20 provided with an amplifier circuit for varying a gain in an optional range less than '1' and practically attenuating the input signals by being controlled by the control signals of the output of the temperature control circuit 40, the input signals are inputted to the analog circuit 30 of a bipolar differential amplifier provided with an input signal linearity limit for fluctuating along with the temperature. Then, the allowable swing of the input signals is limited, amplification is performed and the output signals 14 of the function of the input signals are outputted. Thus, the signal swing of the input signals is maintained at an almost fixed amount less than the maximum signal swing allowed by the analog circuit 30 at a given temperature, and even though a signal level is raised, noise is not increased corresponding to it.

公开(公告)号：SG80647A1

公开(公告)日：2001-05-22

申请号：SG1999004464

申请日：1999-09-10

Applicant: IBM

Inventor： RICK ALLEN PHILPOTT ,  GREGORY SCOTT WINN

IPC: G11B5/00 ,  G11B5/39 ,  G11B5/455 ,  G11B19/04 ,  G11B7/09 ,  G11B20/10 ,  G11B27/36

Abstract: An apparatus and method for measuring an amplitude of a readback signal obtained from a data storage medium involves transmitting the readback signal to a gain modifying amplifier, such as a variable gain amplifier (VGA)(76), preferably provided in the read channel. A voltage signal associated with a loop gain of the amplification circuitry is sensed and compared with a number of control voltage signals, each of the control voltage signals being associated with a corresponding digital word value. The digital word value associated with a control voltage signal that is equal to the sensed voltage signal represents the relative amplitude of the readback signal. Gain characterization circuitry may further be combined with readback signal amplitude measuring circuitry (75), preferably in-situ a read channel, to obtain the absolute amplitude of a readback signal. Gain characteristics of the amplification circuitry are determined by applying reference voltage signals associated with corresponding pre-established gain values to the signal input of the gain modifying amplifier. A control voltage signal is selectively applied to the amplifier for each of the reference voltage signals until the amplifier output voltage signal is substantially equal to a pre-established reference voltage signal. Amplitude measurements may thereafter be taken to obtain the absolute amplitude of readback signals. Readback signal amplitude measurements may be performed when the read channel is in a read mode, idle mode, or servo mode of operation.