General Instrument Corporation

Motorola Corporation

General Instrument Corporation of Delaware

David J Smentek

William C Hart, Jr

Ronald E Wilson

John L Moran, Iii

Richard J Keniuk

Brian Creed

John L Moran

William C Hart

A mixer apparatus (), such as an integrated circuit (IC) mixer is provided for improving the physical layout of devices containing mixers. The mixer includes a multiplier () with an input port (), an output port (), a first switchable local oscillator input port () and a second switchable local oscillator input port (). The dual switchable local oscillator ports are located on either side of the mixer, between the input side and the output side. The dual switchable local oscillator ports allow the mixer to provide more flexibility in integrated circuit and printed circuit board design layouts involving mixer apparatus. For example, in dual channel devices, a local oscillator can be coupled to a pair of the mixers using transmission lines that do not have to be routed around the integrated circuit, to a different level of the printed circuit board or underneath one of the mixers.

Mixer apparatus having switchable local oscillator inputs

The present invention provides methods and apparatus for calibrating and controlling output power levels in a broadband communication system. The power level of an intermediate frequency (IF) signal may be varied at a first attenuator. The IF signal from the first attenuator may be frequency converted at a mixer to provide a desired transmit frequency converted signal. The power level of the frequency converted signal may be adjusted at a second attenuator. The signal may be sampled after the second attenuator in order to detect its output power level. The detected output power level may be compared with a reference level to obtain a difference signal. The difference signal may be used in a feedback loop to adjust the power level of the signal output from the first attenuator so that a constant output power level is maintained. Methods and apparatus for calibrating output power levels are also provided.

Methods and apparatus for calibrating and controlling output power levels in a broadband communication system

A method and an apparatus are employed for individually monitoring the connectivity status of cables connected at a cable modem termination system (CMTS), where the cables conduct upstream and downstream RF communication signals. The monitoring is self-contained within the CMTS. The monitoring is achieved by producing a reference signal having a frequency outside the frequency range of the RF communication signals. The reference signal is injected onto the RF communication signal. The power level of the reference signal is detected within the CMTS, whereby the power level correlates with an expected cable load impedance. A DC control voltage based on the detected power level of the reference signal is generated, which allows a controller to determine the connectivity statuses of the connected cables.

Non-intrusive cable connection monitoring for use in HFC networks

A loop filter and amplifier ( ) is configured to generate a control voltage (V ) by applying low gain to a correction voltage (V ) in response to an input signal (V ) indicating that the VCO ( ) is to operate at low frequencies and applying high gain to the correction voltage in response to the input signal indicating that the VCO is to operate at high frequencies. A loop filter and amplifier ( ) is configured to generate a control voltage (V ) by shifting the control voltage by an amount determined by an offset voltage (V ) and by adjusting the control voltage with a correction voltage (V ). An operational amplifier ( ) is configured to generate a difference between the amount determined by the offset voltage and the correction voltage.

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Addison, IL, United States of America

David J Smentek