Electricity: measuring and testing – Measuring – testing – or sensing electricity – per se – Demand – excess – maximum or minimum
Reexamination Certificate
2001-11-21
2004-08-10
Cuneo, Kamand (Department: 2829)
Electricity: measuring and testing
Measuring, testing, or sensing electricity, per se
Demand, excess, maximum or minimum
C327S094000
Reexamination Certificate
active
06774617
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to peak detectors and more particularly to a peak detector for a small input signal.
BACKGROUND OF THE INVENTION
In disks, such as DVD or DVD-RAM, information is recorded in sector units. A sector includes a header information area having a physical identification data and a user data area. The header information area is typically divided into a peak header area and a bottom header area, and user data is divided into land area and groove area. In DVD-RAM disks, a track is formed spirally, and the track is shifted laterally at a predetermined reference point. The reference point usually becomes a starting point of the first sector.
In DVD applications, peak detectors are used. An AC peak detector is non-linear circuit used to obtain a steady state amplitude at a level of the peak amplitude of the input AC signal. The input AC signal need not be a uniform sinusoidal or an infinite sum of sinusoidals such as in a square wave signal, but any signal with approximately complimentary positive and negative voltage peaks, such as communication data signal can be an AC signal.
A number of peak detector designs are known, however, each design has shortcomings which limit the range of operability and performance within that range. In particular, there is a need for peak detectors which detect peaks with amplitudes as low as 50 or even 20 millivolts. The known designs do not demonstrate acceptable performance at such levels and more particularly has dead zones where a new peak is not recorded.
FIG. 1
illustrates a peak hold circuit. An input signal is input to the base of transistor
100
. A current flows from collector to base of collector
100
. If the current exceeds the current flowing in the constant current source
102
, current flows through capacitor
104
and charges up capacitor
104
. The voltage on capacitor
104
is the peak hold voltage.
FIG. 2
illustrates a typical input voltage. As discussed before, the input signal need not be sinusoidal.
FIGS. 2 and 3
illustrates wave forms including the held voltage at the top of the wave form.
FIG. 3
illustrates the relationship between the input amplitude and the peak hold voltage and the input amplitude. As can be very clearly seen, this circuit introduces a large amount of dead region that is not representative of the peak voltage.
SUMMARY OF THE INVENTION
The present invention provides a peak hold circuit that includes a track and hold circuit and a comparator circuit which provide improved peak detection with minimal dead regions.
REFERENCES:
patent: 5594384 (1997-01-01), Carroll et al.
patent: 5986481 (1999-11-01), Kaminishi
patent: 5995166 (1999-11-01), Kawano
patent: 2004/0027174 (2004-02-01), Ballentin et al.
Brady W. James
Cuneo Kamand
Hollington Jermele
Swayze, Jr. W. Daniel
Telecky , Jr. Frederick J.
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