Analog Devices,inc.

Stmicroelectronics N.v.

Ronald Kroesen

Janos Kovacs

Philip Eugene Quinlan

Jason D Byrne

Kevin J McCall

A burst error limiting symbol detector system includes a symbol detector circuit responsive to a truncated sample signal for detecting binary symbols encoded in a truncated sample signal with reference to at least one preselected reference level; a feedback equalizer circuit for providing a feedback equalizer signal for cancelling undesired samples in an input signal; a summing circuit, responsive to the input signal and the feedback equalizer signal for providing the truncated sample signal to the symbol detector circuit; and a feedback suppressor circuit responsive to the truncated sample being within a predetermined range of the preselected reference level for suppressing the feedback equalizer signal to prevent marginal detected binary symbols from contributing to the cancellation of undesired samples in the input signal.

Burst error limiting symbol detector system

A read system for implementing PR4 and higher order PRML signals includes: a continuous time programmable filter, for receiving a read signal representative of a binary signal from a storage medium and for shaping the read signal into a PR4 shaped read signal; an analog finite impulse response (AFIR) filter, responsive to the continuous time programmable filter, for sampling and forming the PR4 shaped read signal into a PR4 shaped multilevel read signal; an analog to digital converter, responsive to the AFIR filter, for converting the PR4 shaped multilevel read signal from analog to digital; a data sequence filter, responsive to the analog to digital converter, for transforming the PR4 shaped multilevel digital read signal to a predetermined order PRML signal; and a Viterbi detector, responsive to the data sequence filter, for detecting the binary signal from the predetermined order PRML signal.

Read system for implementing PR4 and higher order PRML signals

A dynamic phase selector phase locked loop circuit includes: an A/D converter for receiving an input to be sampled; a phase detection circuit for determining the phase error between the input signal and a clock signal; a clock circuit, responsive to the phase detection circuit, for providing the clock signal to the A/D converter for timing the sampling of the input signal; the clock circuit including a delay circuit having a number of delay taps; and a phase selector circuit, responsive to the phase detection circuit, for initially gating the clock signals to the A/D converter from the clock circuit, and enabling one of the delay taps to dynamically adjust the phase of the clock signal and reduce the initial phase error.

Dynamic phase selector phase locked loop circuit

A phase locked loop system or other second order feedback system whose natural frequency scales with its output and whose damping factor remains constant includes a filter circuit having a scaling channel for scaling the error, an integrating channel for integrating the error, and a summing circuit for combining the scaled error and integrated error; an integrator circuit responsive to the summing circuit to produce an output signal, the gain of the integrator circuit being proportional to its output signal; and a control circuit for controlling the gain of the integrating channel proportional to the output signal and maintaining constant the ratio of and scaling the product of the unity gained frequency and the zero frequency of the feedback system to keep constant the damping factor and to scale the natural frequency of the feedback system with the output signal, respectively.

Hybrid phase locked loop

A center frequency controlled phase locked loop system includes a primary phase locked loop having a first voltage controlled oscillator including a first voltage to current converter whose output current drives a first current controlled oscillator to produce the primary clock signal to be locked onto an input signal; a second phase locked loop having a second voltage controlled oscillator including a second voltage to current converter whose output current drives a second current controlled oscillator to produce the synthesized clock signal whose frequency is approximately that of the input signal or integral multiple thereof; and a current copier circuit for copying the output current from the second voltage to current converter and delivering it to the first current controlled oscillator to maintain the center frequency of the first voltage controlled oscillator at approximately the output frequency of the synthesized clock signal.

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Harvard, MA, United States of America

Ronald Kroesen