Abstract:
A modulator (100) for producing a modulated carrier signal in a radio transmitter and suitable for coupling to a power amplifier (40) whose output power is controllable by a DC supply voltage. The modulator (100) comprises quadrature generation means (110) for generating baseband in-phase (I) and quadrature-phase (Q) signal components for a non-constant envelope modulation scheme from a base band data signal, means (30, 32) for scaling the I and Q signal components by a scaling factor for effecting transmitter power control, quadrature modulation means (34 for modulating a carrier signal with the I and Q signal components, and power supply control means (120) for generating, from a baseband signal prior to modulation of the carrier, a power supply control signal which tracks the envelope of the modulated carrier signal for controlling a DC supply voltage of the power amplifier (40). The modulator (100) may comprise additional modes of operation encompassing peak envelope tracking, constant envelope modulation, and envelope elimination and restoration.
Abstract:
A method and apparatus for generating the adaptive gain control signals in a communications receiver is disclosed. The present invention can be used with existing two-stage gain architectures, and overcomes many undesirable characteristics of the previous mechanism. An apparatus is presented wherein each of a plurality of RF AGC gain controllable amplifiers (140 and 150) are individually controlled by individual AGC control signals generated by an AGC controller (105) so that the level of the output signal from each of the RF AGC gain controllable amplifiers is individually optimized for tuner performance (170 and 190).
Abstract:
A dynamically varying linearity system 'DVLS' (102) capable of varying the linearity of a radio frequency (RF) front-end (112) of a communication device (100) responsive to receiving a condition signal indicating a desired mode of operation of a transmitter (112). The DVLS may include a condition signal indicative of the desired mode of operation and a controller (110) that adjusts the linearity of the transmitter responsive to the condition signal. The condition signal may be responsive to a user interface (106). The controller, responsive to the condition signal, may dynamically adjust the operating current of the transmitter.
Abstract:
A transmitter includes a dual mode modulator and an amplifier coupled to the dual mode modulator. The dual mode modulator implements a linear modulation scheme during a first mode of the modulator to produce a variable envelope modulated signal. The dual mode modulator implements a non-linear modulation scheme during a second mode of the modulator to produce a constant envelope modulated signal. The amplifier is biased as a linear amplifier during the first mode of the modulator and is biased as a non-linear amplifier during the second mode of the modulator. A feed-forward connection between the dual mode modulator and the amplifier is used to indicate a change in modulation mode and to adjust the bias of the amplifier. A power of the constant envelope modulated signal is increased such that an operating point of the amplifier remains substantially constant during the first and second modes of the modulator.