Maxim Integrated Products, Inc.

Joel David Birkeland

Robert G Meyer

Matthew Glenn Waight

Charles John Razzell

Frank Prestrelski

An energy efficient, low distortion amplification apparatus includes: a differential amplifier having a pair of differential inputs, a pair of outputs, and a bias current control input; a digital delay having an n-bit word input and an m-bit word output; a digital-to-analog converter (DAC) having an input coupled to the output of the digital delay and a pair of differential outputs coupled to the pair of differential inputs of the differential amplifier; and a bias current controller having an input coupled to the digital delay and having an output coupled to the bias current control input of the differential amplifier.

Energy efficient, low distortion amplification apparatus

An attenuation circuit uses a voltage controlled variable resistance transistor as a signal attenuator for receivers operating in the zero Hz to about 30 MHz range. The transistor functions in the linear region to linearize the transistor resistance characteristics used for signal attenuation. In an exemplary application, the attenuation circuit is used as an RF attenuator for AM radio broadcast receivers and amplifiers with automatic gain control. Multiple attenuation circuits can be coupled in parallel, each attenuation circuit having a different sized variable resistance transistor, to form sequentially activated stages that increase the range of attenuation while minimizing distortion.

Low distortion MOS attenuator

Voltage controlled variable attenuators are described that are configured to be coupled to a transmission path to furnish variable attenuation of a signal, such as a radio frequency signal. In one or more implementations, the voltage controlled variable attenuator includes at least one transistor. The transistor has an open configuration for at least substantially preventing the flow of current through the transistor, and a closed configuration for at least partially allowing the flow of current through the transistor. The variable attenuator also includes a resistive component coupled to the transistor, and configured to couple to the transmission path. The resistive component is configured to at least partially mitigate non-linear effect when the transistor transitions from the open configuration to the closed configuration. The transistor and the resistive component are configured to at least partially attenuate a signal transmitted along the transmission path when the transistor is in the closed configuration.

Voltage controlled variable attenuator

A tunable receiver is disclosed including a plurality of select filters to perform an initial band selection, a variable-gain low noise amplifier (LNA) whose gain is controlled to prevent its output power level to exceed a pre-determined power threshold, a plurality of digitally-tunable tracking filters to pass signals within a selected channel and to reject signals in a corresponding image band, a second LNA to further amplify the received RF signal and to generate differential signal outputs, a down converting stage which converts the received RF signal to an IF signal while rejecting signals in the image band, an IF trap to further reject undesired signals present at the output of the down converting stage, an IF amplifier to amplify the IF signal to compensate for losses, an IF filter to provide channel select and reject undesirable signals, and a variable-gain IF amplifier to amplify the IF signal and maintain its power level within specification.

Broadband single conversion tuner integrated circuits

The present invention teaches a variety of driver amplifiers having a transmit mode suitable for driving the load resistance of a network with an amplified version of the input signal, and a standby mode wherein the driver amplifier consumes substantially no current and isolates the load resistance from the input signal. These amplifiers are also characterized in that during transitions back and forth between standby mode and transmit mode, a minimum of standby transient leaks out onto the network. Further, the noise power delivered to the network in standby mode is substantially minimized, the remaining noise being primarily due to thermal noise produced by a resistor utilized to provide matched termination to the network.

Growing community of inventors

North Plains, OR, United States of America

Joel David Birkeland