Motorola Corporation

Freescale Semiconductor,inc.

David S Peckham

Gregory Redmond Black

Armin Werner Klomsdorf

James John Crnkovic

Kevin B Traylor

Jin D Kim

Frank Robert Skutta

Arul Balasubramaniyan

Richard B Meador

James S Irwin

David A Newman

George Norris

Robert M Johnson, Jr

Benjamin Gilsdorf

Michael F Landherr

Mark A Pennock

Constantine Vlahos

David Z Ding

Systems and techniques are described for applying a polar bias modulation having a phase component and an amplitude component to a signal amplified by a power amplifier. The power amplifier (PA) has a plurality of amplifier gain stages and is configured to amplify an input to create an amplifier output signal. The input to the power amplitude is phase modulated based upon the phase component of the polar bias modulation, but need not be amplitude modulated. Amplitude modulation is provided by logic that includes a detector configured to receive an indication of the amplifier output as a feedback signal, a control module configured to generate a control signal based upon both the feedback signal and the amplitude component of the polar bias modulation, and a bias circuit configured to adjust a bias signal associated with at least one of the plurality of amplifier gain stages in response to the control signal. Such a modulation scheme may be readily applied in enhanced data rate for global service mode (GSM) evolution (EDGE) applications, as well as in other environments that make use of polar modulation.

System and method for polar modulation using power amplifier bias control

A multi-mode transmitter architecture is configurable for multiple modulation modes using either polar or polar-lite modulation. Multiplexed signal paths and reconfigurable components are controlled for performance in GMSK and EDGE burst modes. Polar-lite EDGE modulation is programmed by setting a multiplexer coupling a first amplitude modulated signal path with a frequency modulated signal path input to a dual-mode power amplifier for amplification of the combined EDGE transmission signal. In full-polar EDGE modulation, amplitude modulated signal is multiplexed into a second amplitude modulated signal path for A/D conversion and comparison with a polar feedback signal coupled from the power amplifier output. The resulting comparison is applied to a power control port of the power amplifier to amplitude modulate the EDGE transmission output. Multiplexers are configured to disconnect the amplitude modulated paths when operating in GMSK signaling for both full-polar and polar-lite modulation. Multiplexers selectively couple power feedback into the second amplitude modulated signal path to provide power control and output power ramping for burst transmissions.

Configurable multi-mode modulation system and transmitter

Method and apparatus are provided for protecting radio frequency (RF) power amplifiers. A circuit () is provided for limiting a supply current to a first stage (Q) of the RF power amplifier having a second stage (Q) coupled to the first stage. The circuit comprises a comparator () having first and second inputs and an output, and a switching circuit () having an input coupled to the output of the comparator () and having an output configured to couple to the first stage (Q). The first input of the comparator () is configured to receive the supply current, and the second input is configured to receive a current supplied to the second stage (Q). The comparator () is configured to compare a ratio of the supply current to the first stage to the current supplied to the second stage (Q) with a predetermined value. The switching circuit () is configured to limit the supply current to the first stage (Q) when the ratio exceeds the predetermined value.

Method and apparatus for protecting RF power amplifiers

A multiband and multimode transmitter circuit () includes two separate oscillators, such as at least a first oscillator circuit (), a second oscillator circuit (), a corresponding first signal processing circuit (), and second signal processing circuit () to produce a first output frequency signal () defined within the first or second band of frequencies in response to a transmitter input signal (). Each oscillator and corresponding signal processing circuit () may be optimized for the lowest power consumption while meeting the noise performance criteria in each of the multiple frequency bands. The multiband and multimode transmitter circuit () may produce the transmitter output signal () with either linear modulation or nonlinear modulation and at a first band or second band frequencies.

Multiband and multimode transmitter and method

A cross-coupled cascode voltage controlled oscillator including a variable-frequency tank circuit, first and second cascode-coupled active devices coupled to the tank circuit, and third and fourth cascode-coupled active devices coupled to the tank circuit, the first and second active devices being cross-coupled to the third and fourth active devices. The invention produces lower drain the gate voltages resulting in fewer device failures.

Cross coupled cascode voltage controlled oscillator

Systems and methods are described for a band switchable voltage controlled oscillator. A method comprises: operating said voltage controlled oscillator in a first frequency band by switching a first capacitive circuit having a capacitance that varies with a tuning voltage; and operating said voltage controlled oscillator in a second frequency band by switching a second capacitive circuit having a capacitance that does not vary with the tuning voltage. An apparatus comprises: a switchable variable capacitance circuit; a switchable fixed capacitance circuit coupled to the switchable variable capacitance circuit; a controller for selectively switching said switchable fixed and variable capacitance circuits; a fixed tank capacitance circuit coupled to the switchable fixed capacitance circuit; a main tuning voltage variable capacitance circuit coupled to the fixed tank capacitance circuit; a tank inductance coupled to the main tuning voltage variable capacitance circuit; and an amplifier circuit coupled to the tank inductance.

Band switchable voltage controlled oscillator with substantially constant tuning range

A multiple frequency band receiver (,) receives at least two frequency bands that are close but not adjacent. A first bandpass filter (,) passes signals in the first frequency band. A second bandpass filter (,) passes signals in the second frequency band. The first and second filters each attenuate signals between the first and second frequency band to at least a first level so as to provide selectivity in the frequency range between the first and second frequencies to prevent the signals between these frequency bands from being further processed by the communication device. A third filter (,) coupled to first and second filters passes signals in both the first and second frequency band and attenuates signals above the pass band of the higher of the first and second filters and below the lower of the first and second filters.

Multiple frequency band receiver

An exciter matching circuit (,), interstage matching circuit (,), and harmonic filter matching circuit (,) match impedances at the input to a two-stage power amplifier (,), between the first stage (,) and the second stage (,) of the power amplifier (,), and at the output of the power amplifier (,) for more than one frequency band of interest. In a GSM/DCS dual band radiotelephone (,), the matching circuits (,) provide low return loss at 900 MHz when the dual band transmitter (,) is operating in the GSM mode. The harmonic filter matching circuit (,) also filters out signals at 1800 MHz, 2700 MHz, and high order harmonics. When the dual band transmitter (,) is in DCS mode, however, the matching circuits (,) provide a low return loss at 1800 MHz and filter out signals at 2700 MHz and harmonics of 1800 MHz.

Impedance matching for a dual band power amplifier

An exciter matching circuit (125), interstage matching circuit (134), and harmonic filter matching circuit (140) match impedances at the input to a two-stage power amplifier (130), between the first stage (132) and the second stage (136) of the power amplifier (130), and at the output of the power amplifier (130) for more than one frequency band of interest. In a GSM/DCS dual band radiotelephone (101), the matching circuits (124, 134, 140) provide low return loss at 900 MHz when the dual band transmitter (110) is operating in the GSM mode. The harmonic filter matching circuit (140) also filters out signals at 1800 MHz, 2700 MHz, and high order harmonics. When the dual band transmitter (110) is in DCS mode, however, the matching circuits (124, 134, 140) provide a low return loss at 1800 MHz and filter out signals at 2700 MHz and harmonics of 1800 MHz.

According to the apparatus of the present disclosure, dual gate control and dual gain control uses variable voltages on the gates of first stage (302) and a second stage (304) to control the output power. In alternate embodiments, dual drain control is also employed using a variable voltage supply on the drains of the first stage (302) and the second stage (304). In particular, a level shifter circuit (421) is employed to convert a positive voltage gate control signal to negative voltage with respect to ground. Drain current limiting circuits (417, 419) are used to sample drain currents and generate gate voltages to maintain a desired current ratio between stages of a multi-stage amplifier. When dual drain control is also employed, a 1:1 ratio of drain control voltages is employed at low power levels, with a single drain control at higher power levels.

Apparatus for amplifying an RF signal

A unique method and apparatus modifies the load impedance at the output of a power amplifier by varying a voltage variable capacitor (VVC) (310) to maximize the efficiency of the power amplifier (304). A comparator (509) generates amplifier control signal (211) based upon a detected power output signal (216) and a reference signal. In addition to providing power control, the control signal is also coupled to a VVC circuit (506) to control the output impedance of the power amplifier. In an alternate embodiment, a separate VVC control signal (527) based upon a comparison of the power control signal and the battery voltage is coupled to a VVC. In another alternate embodiment, a second VVC can be coupled in parallel to the first VVC. The second VVC is preferably controlled by a signal (805) based upon the current in the power amplifier. Finally, an alternate embodiment incorporates a VVC circuit (506) at the input of the power amplifier to compensate for variations in input impedance to improve other power amplifier parameters such as IM, gain, output power and noise level.

Method and apparatus for amplifying a signal

A method and apparatus enables a communication device (100) to operate in multiple bands, such as GSM 900 MHz, DCS 1800 MHz, and DCS 1900 MHz bands, by eliminating the need for a mixer for each band. In a dual band GSM/DCS 1800 radiotelephone, for example, the local oscillator (LO) injection frequencies for both GSM and DCS bands are provided to a mixer (234) through the use of combination filters (222, 246). Thus, the duplexing and matching requirements to the mixer input are simplified and the signal losses are minimized. The common output ports of the GSM RX/LO combination filter and DCS RX/LO combination filter are duplexed to the input of the mixer. Also, the input impedance matching of the mixer is designed to match the impedance for the received signals in each band, as well as provide an RF trap at the IF frequency. The match at the output of the mixer is designed to match the impedance of the IF filter and provides a low impedance to RF input frequencies. Finally, a tri-band radiotelephone is also described.

Method and apparatus for receiving communication signals

A transmitter VCO (204) includes nodes for receiving a band selector voltage for altering the base-emitter capactance of a transistor to enable the VCO to act as an oscillator in the appropriate band, and for altering the resonator capacitance to change the resonant frequency of the oscillator. The method and apparatus enables oscillation in different frequency bands for dual mode communication devices.

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Barrington Hills, IL, United States of America

David S Peckham