4.6 Read/write Circuit
C141-E120-02EN
4-13
4.6.3 Read circuit
The head read signal from the PreAMP is regulated by the automatic gain control
(AGC) circuit. Then the output is converted into the sampled read data pulse by
the programmable filter circuit and the flash digitizer circuit. This clock signal is
converted into the NRZ data by the 16/17 GCR decoder circuit based on the read
data maximum-likelihood-detected by the Viterbi detection circuit, then is sent to
the HDC.
(1) AGC circuit
The AGC circuit automatically regulates the output amplitude to a constant value
even when the input amplitude level fluctuates. The AGC amplifier output is
maintained at a constant level even when the head output fluctuates due to the
head characteristics or outer/inner head positions.
(2) Programmable filter circuit
The programmable filter circuit has a low-pass filter function that eliminates
unnecessary high frequency noise component and a high frequency boost-up
function that equalizes the waveform of the read signal.
Cut-off frequency of the low-pass filter and boost-up gain are controlled from the
register in read channel by an instruction of the serial data signal from MPU
(M5). The MPU optimizes the cut-off frequency and boost-up gain according to
the transfer frequency of each zone.
Figure 4.6 shows the frequency characteristic sample of the programmable filter.
Figure 4.6 Frequency characteristic of programmable filter
-3 dB
Summary of Contents for MHN2100AT - Mobile 10 GB Hard Drive
Page 1: ...C141 E120 02EN MHN2300AT MHN2200AT MHN2150AT MHN2100AT DISK DRIVES PRODUCT MANUAL ...
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Page 52: ...Installation Conditions 3 14 C141 E120 02EN Figure 3 16 Example 2 of Cable Select drive drive ...
Page 58: ...Theory of Device Operation 4 6 C141 E120 02EN Figure 4 3 Circuit Configuration ...
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Page 174: ...Interface 5 98 C141 E120 02EN g d f f d e Figure 5 7 Normal DMA data transfer ...
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