Maxim Integrated Products, Inc.

Pericom Semiconductor Corporation

Howard Luong

Matthew Glenn Waight

James W Marsh

Gerry C T Leung

A method and apparatus for an electronically tuned agile integrated bandpass filter is described. In one embodiment, the invention is an intermediate frequency filter for use in an integrated circuit. The filter includes a first filter stage, including a first LC resonator. The first filter stage further includes a first adjustable capacitor array coupled to the first LC resonator. The first adjustable capacitor array has an effective capacitance value adjustable through use of a first plurality of programmable data storage locations. The first plurality of programmable data storage locations are programmable through a serial control interface.

Electronically tuned agile integrated bandpass filter

A phase-locked loop (PLL) has an analog divider in the feedback path that receives either the in-phase or quadrature-phase pair of outputs from a voltage-controlled oscillator (VCO) while the other pair, 90-degree out-of-phase, of outputs from the VCO is used for the PLL output. Phases between the PLL's input and output are inherently aligned. The analog output of the analog divider is converted to a digital clock signal and applied to a cascade of digital dividers to generate a reduced feedback clock. The reduced feedback clock is applied to the D input and the digital clock signal is applied to the clock input of a pseudo D-flip-flop that drives the feedback input of a phase-frequency detector that drives the charge pump to the VCO input. Another cascade of digital dividers and pseudo D-flip-flop re-align the reference clock input to the phase-frequency detector. Analog and digital re-alignment circuits reduce internal skew.

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Renton, WA, United States of America

Howard Luong