Dsp Group Limited

University of Minnesota

Yongwang Ding

Ramesh Harjani

Michael E Butenhoff

The disclosure relates to an automatic level control technique for RF amplifiers in a communication system, such as a wireless communication system. The invention provides an automatic level control technique to compensate for variations in the gain of an RF amplifier, which may be a transmitter amplifier or a receiver amplifier. In accordance with the invention, the gain of the RF amplifier can be controlled as a function of the output of a voltage controlled oscillator (VCO) circuit provided in the communication system. A VCO typically includes a buffer amplifier with a structure similar to that of the RF amplifier used in the transmit or receive side of the RF front-end. By tracking changes in the output of the VCO buffer amplifier, an automatic level control (ALC) input to the RF amplifier can be adjusted to compensate for process- and temperature-based variations in amplifier gain.

Automatic level control for radio frequency amplifiers

In general, the disclosure is directed to techniques for enhancing power efficiency and linearity in an RF power amplifier. In accordance with the invention, a combination of different class power amplifiers is implemented in a parallel configuration to overcome the trade-off that exists between power efficiency and linearity. In particular, a class A amplifier and a class B amplifier are arranged in parallel to produce a combined amplifier output for an input signal. With bias voltages set to achieve a desired operating ratio between the class A and class B amplifier, the combined amplifier can provide a high power gain over a larger input range. In addition, the class B amplifier can provide increased power efficiency for larger inputs.

Radio frequency CMOS amplifier with enhanced linearity and power efficiency

Circuits and methods that improve linearity with use of cancellation of at least a portion, and preferably, substantially all of, at least one significant harmonic from the output of a primary circuit, e.g., the 3harmonic, using the output of a substantially functionally identical auxiliary circuit.

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Austin, TX, United States of America

Yongwang Ding