Motorola Corporation

James F Long

Yuda Yehuda Luz

Mark G Obermann

Anthony Kobrinetz

Brian J Budnik

John M Smith

Robert C Elder

Ronald J Wanat

Derek L Tattersall, Jr

The apparatus includes an amplifier (204) having an input and an output, the amplifier output coupled to an input of a Doherty amplifier (208). The Doherty amplifier (208) includes a control input and a Doherty output. The apparatus further includes a detector (224) having an input coupled to the output of the Doherty amplifier (208). The detector provides a detected signal at its output, to a controller (228), the controller responding to the detected signal by producing a first (230) and second control output (231). The first control output is coupled to a switching regulator (232) input, the switching regulator having an output coupled to the control input of the Doherty amplifier. The second control output is coupled to a control input of a variable attenuator (202), the output of the variable attenuator coupled to the input of the amplifier (204).

Apparatus and method for amplifying a signal

A method and apparatus in a feedforward amplifier (100) includes a summer (293) summing the desired signal (12) with a pair of tag signals (241, 242). An error signal (226) is coupled with a delayed version of the summed signal (48). The phase and amplitude of signals (226, 237) are adjusted according to a first and second gradient decent controllers (221, 231) output signal (225) which is based on the first DC signal (224) and output signal (235). The output signal (235) is based on the detected power level of a leaked signal at the output coupler (62). The adjustment of the input signal (237) to the second amplifier, when the detected power level fluctuation exceeds a predetermined threshold level, is repeated. The tag signals (241) are produced in phase lock with the sweeping detecting (222) function.

Feedforward amplifier

An apparatus (10) for adjusting peak-to-average power of a multicarrier signal. The apparatus (10) comprises a first (26) and second (28) combiner, a phase-changing device (30), and a switch (36). The first combiner (26) receives a first group of channels (20) and a second group of channels (22) and produces a first combined signal (46). The phase-changing device (30) receives the first group of channels (20) and produces a group of phase-adjusted channels. The second combiner (28) receives the phase-adjusted channels and the second group of channels (22) and produces a second combined signal (48), and the switch (36) responds to the first (26) and second (28) combiners and selects at least one of the first (46) and second (48) combined signals.

Transmitter which adjusts peak-to-average power of a multicarrier signal

A wireless communication system for simultaneously communicating overlapping wideband and narrowband signals. The system includes a transmitting station for embedding one or more narrowband signals (3-5) in a wideband signal (1) having a frequency spectrum encompassing the narrowband signals, and transmitting the resulting composite wideband signal (2). The system also includes a receiving station for receiving a composite wideband signal (60) and separating the embedded narrowband signal(s) (62, 63) from the wideband signal (61). In one embodiment, a cellular radiotelephone base station (35) is operable as both the transmitting and receiving station, communicating with remote subscriber units (29-31) having conventional transceivers (FDMA, TDMA and/or CDMA). The base station transmitter circuitry (10-17) includes FM and CDMA signal generators (10, 12), a combiner (15) for embedding the narrowband signal (3-5) in the wideband signal (1), and an AGC (14) and power detectors (11, 13) for controlling the narrowband signal power. The receiving circuitry includes a CDMA processing circuit having an FFT circuit (41), a threshold detector (42), a notch filter (43), and an inverse FFT circuit (44) for separating narrowband signals (62, 63) from the CDMA signal (61).

Method and apparatus for simultaneous wideband and narrowband wireless

In a quantization noise reduction circuit (200), a feedback signal (W)is added to an input signal (X) to the quantization circuit to reduce quantization noise. The feedback signal is generated as a filtered difference between a sample of a N bit signal (X') and a time coincident sample of a M bit quantized signal, where M&lt;N. The feedback signal is subtracted from the input signal (X) prior to quantization thereby introducing out of band noise into the input signal for reducing in band noise in the quantized signal (Y).

Method and apparatus for reducing quantization noise

A cellular radiotelephone communication system cell site equipment is provided. The cell site equipment includes a radio frequency transmitter operating as one signal frequency source. In addition, the cell site equipment includes a first and a second signal combiner device tuned to a first and a second signal frequency, respectively. Further, the cell site equipment includes a radio frequency switching mechanism, operatively coupled to the radio frequency transmitter, the first signal combiner device, and the second signal combiner device, for coupling the radio frequency transmitter to either of the first and the second signal combiner devices. In one embodiment, each signal combiner device includes a resonant cavity for isolating a signal frequency source from other signal frequency sources and a coupling for coupling the isolated signal frequency source to a common transmitter output. In an alternative embodiment, each signal combiner device includes a resonant cavity for isolating a signal frequency source from other signal frequency sources and a coupling for coupling the isolated signal frequency source of the first and the second signal combiner device to a first and a second common transmitter output, respectively.

High capacity sectorized cellular communication system

Briefly described the present invention is a feed forward amplifier network (200) employing a frequency swept pilot tone signal (212) in order to reduce the distortion generated by the network's power amplifier (202). Initially a composite input signal (216) comprising either wide (520) and/or narrow (510) bandwidth modulation formats is input into the network (200). In addition, the frequency swept pilot tone (212), generated for example by a variable frequency oscillator (213), is injected into the input path of the power amplifier (202). Thereafter, distortion cancellation is employed to generate an amplified output signal (217) having output components (510,520) which replicate those within the input signal (216). Thereafter, pilot tone power is detected (by 215) within the amplifier passband where the output components (510,520) are absent, in order to ascertain the average pilot tone power remaining within the amplified output signal (217). In response to this detection, various amplifier network characteristics are adjusted (by 214, 208 and 209) in order to reduce the amount of pilot tone at the amplifier network output (217).

High dynamic range modulation independent feed forward amplifier network

The present invention discloses a method and apparatus for optimizing the performance of a power amplifier circuit. In accordance therewith, one of the intermodulation products generated during a power amplifier's operation is selected. This selection is based upon the intermodulation product's amplitude. Next, the intermodulation product's amplitude is compared to a predetermined threshold. Based upon this comparison, various power amplifier circuit operating parameters are altered in order to improve the circuit's intermodulation performance or to maximize its operating capacity.

Method and apparatus for optimizing the performance of a power amplifier

A feed forward distortion minimization circuit which receives an input signal and routes the input signal along two signal paths is disclosed. One path, the main signal path, includes a distortion generator such as, for example, a power amplifier, which generates an output signal having a distortion component. The other path, the feed forward signal path, includes a delay line responsive to the input signal for feeding the input signal forward, without distortion. The output signal from the distortion generator is combined with a fed forward input signal to form an error signal representative of the distortion component. A feedback circuit is employed to detect a DC current or RF voltage proportional to the error signal's signal strength and to adjust the amplitude and the phase of signals in the feed forward or main signal paths to reduce the carrier to distortion ratio of the error signal. Thereafter, the error signal is subtracted from the main signal path to cancel any distortion components therein. The subtraction is controlled by circuitry which detects distortion at the main signal path output, and adjusts the amplitude and the phase of the error signal, so that when the error signal is subtracted from the main signal path, substantially all distortion is cancelled.

Feed forward distortion minimization circuit

The invention is a controlled ferroresonant power supply with an improved feedback circuit resulting in improved output stability. The feedback circuit is responsive to the low voltage secondary output of the power supply to provide a variable output signal to activate the switch which controls the resonant winding circuit. The improved feedback circuit is responsive to the rectified AC low voltage secondary output for only a portion of its frequency period.

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Glen Ellyn, IL, United States of America

James F Long