Broadcom Corporation

Ralph A Duncan

Tom W Kwan

Pieter Vorenkamp

Klaas Bult

Frank Carr

James Y C Chang

Haideh Khorramabadi

Chun-Ying Chen

Young J Shin

Frank Wayne Singor

Christopher M Ward

Christopher Michael Ward

An integrated receiver with channel selection and image rejection substantially implemented on a single CMOS integrated circuit is described. A receiver front end provides programmable attenuation and a programmable gain low noise amplifier. Frequency conversion circuitry advantageously uses LC filters integrated onto the substrate in conjunction with image reject mixers to provide sufficient image frequency rejection. Filter tuning and inductor Q compensation over temperature are performed on chip. The filters utilize multi track spiral inductors. The filters are tuned using local oscillators to tune a substitute filter, and frequency scaling during filter component values to those of the filter being tuned. In conjunction with filtering, frequency planning provides additional image rejection. The advantageous choice of local oscillator signal generation methods on chip is by PLL out of band local oscillation and by direct synthesis for in band local oscillator. The VCOs in the PLLs are centered using a control circuit to center the tuning capacitance range. A differential crystal oscillator is advantageously used as a frequency reference. Differential signal transmission is advantageously used throughout the receiver.

Fully integrated tuner architecture

An integrated receiver with channel selection and image rejection substantially implemented on a single CMOS integrated circuit is described. A receiver front end provides programable attenuation and a programable gain low noise amplifier. Frequency conversion circuitry advantageously uses LC filters integrated onto the substrate in conjunction with image reject mixers to provide sufficient image frequency rejection. Filter tuning and inductor Q compensation over temperature are performed on chip. The filters utilize multi track spiral inductors. The filters are tuned using local oscillators to tune a substitute filter, and frequency scaling during filter component values to those of the filter being tuned. In conjunction with filtering, frequency planning provides additional image rejection. The advantageous choice of local oscillator signal generation methods on chip is by PLL out of band local oscillation and by direct synthesis for in band local oscillator. The VCOs in the PLLs are centered using a control circuit to center the tuning capacitance range. A differential crystal oscillator is advantageously used as a frequency reference. Differential signal transmission is advantageously used throughout the receiver.

An integrated circuit formed on a semiconductor chip, comprising a low pass filter circuit having a first resistor of a first resistance value and a capacitor of a first capacitance value, wherein the first resistance value and the first capacitance value determine a corner frequency of the filter; and a tuning circuit having a second resistor of a second resistance value, a switched-capacitor of a third resistance value and a comparator that compares two voltage signals to produce a control signal, wherein the control signal adjusts the first and second resistance values as a function of the third resistance value. The corner frequency of the filter can be adjusted by varying one or more reference voltage signals. In combination, the corner frequency of the filter is adjusted by changing the frequency of a clock that controls the switched-capacitor to decrease the circuit sensitivity.

System for tuning a corner frequency of a low pass filter

An integrated VCO having an improved tuning range over process and temperature variations. There is therefore provided in a present embodiment of the invention an integrated VCO. The VCO comprises, a substrate, a VCO tuning control circuit responsive to a VCO state variable that is disposed upon the substrate, and a VCO disposed upon the substrate, having a tuning control voltage input falling within a VCO tuning range for adjusting a VCO frequency output, and having its tuning range adjusted by the tuning control circuit in response to the VCO state variable.

Integrated VCO having an improved tuning range over process and temperature variations

Provided is a switched capacitor feedback circuit including two or more input ports configured to receive a corresponding a number of input signals and at least one output port. The output port is configured to output an adjusting signal. The input signals includes a number of primary signals and two or more reference signals that are associated with a first timing phase of operation. The adjusting signal is produced based upon a comparison between the primary signals the reference signals. Also provided is a pair of active devices having gates coupled together and structured to receive the adjusting signal. The active devices are configured to provide a gain to the adjusting signal in accordance with a predetermined gain factor, and facilitate an adjustment to the number of primary signals based upon the gain during a second timing phase of operation.

Switched-capacitor, common-mode feedback circuit for a differential amplifier without tail current

Method for tuning a corner frequency of a low pass filter

Low pass filter corner frequency tuning circuit and method

System and method for narrow band PLL tuning

Growing community of inventors

Laguna Beach, CA, United States of America

Ralph A Duncan