Abstract: A method for measuring an impedance of an antenna includes generating, by a signal source coupled to the antenna, a radio frequency (RF) signal, applying the RF signal to a directional coupler, and mixing, by a first mixer, a first signal from the directional coupler with a signal, wherein the first signal corresponds to a reflected power from the antenna. The method further includes mixing, by a second mixer, a second signal with the signal, wherein the second signal is offset from the first signal by ninety degrees. The method further includes outputting, by a first lower pass filter (LPF) coupled to an output of the first mixer, a real part of a reflection coefficient of the antenna and outputting, by a second lower pass filter (LPF) coupled to an output of the second mixer, an imaginary part of the reflection coefficient.

Abstract: Embodiments of a method for tuning the resonant frequency of an antenna in a wireless communication device are disclosed, along with embodiments of a wireless communication device using such a method. Embodiments sense the out-of-band impedance of the antenna, which comprises an antenna element and selectively adjustable impedance disposed between the antenna element and a ground plane of the wireless device, and adjust the selectively adjustable impedance to achieve a desired resonant frequency of the antenna. Embodiments separate an antenna signal into an in-band signal and out-of-band impedance, generate an error signal related to the out-of-band impedance, apply the error signal to a controller circuit configurable to generate an impedance error signal representing the change in antenna impedance, and apply the impedance error signal to the selectively adjustable impedance. Embodiments of a method and electronic circuit for determining the change in impedance of an antenna are also disclosed.

Abstract: A method for measuring an impedance of an antenna includes generating, by a signal source coupled to the antenna, a radio frequency (RF) signal, applying the RF signal to a directional coupler, and mixing, by a first mixer, a first signal from the directional coupler with a signal, wherein the first signal corresponds to a reflected power from the antenna. The method further includes mixing, by a second mixer, a second signal with the signal, wherein the second signal is offset from the first signal by ninety degrees. The method further includes outputting, by a first lower pass filter (LPF) coupled to an output of the first mixer, a real part of a reflection coefficient of the antenna and outputting, by a second lower pass filter (LPF) coupled to an output of the second mixer, an imaginary part of the reflection coefficient.

Abstract: Embodiments of a method for tuning the resonant frequency of an antenna in a wireless communication device are disclosed, along with embodiments of a wireless communication device using such a method. Embodiments sense the out-of-band impedance of the antenna, which comprises an antenna element and selectively adjustable impedance disposed between the antenna element and a ground plane of the wireless device, and adjust the selectively adjustable impedance to achieve a desired resonant frequency of the antenna. Embodiments separate an antenna signal into an in-band signal and out-of-band impedance, generate an error signal related to the out-of-band impedance, apply the error signal to a controller circuit configurable to generate an impedance error signal representing the change in antenna impedance, and apply the impedance error signal to the selectively adjustable impedance. Embodiments of a method and electronic circuit for determining the change in impedance of an antenna are also disclosed.

Abstract: A device may include an envelope detector to generate an envelope signal from the input signal, a drain bias controller to adjust a drain bias of the amplifier based on the envelope signal, a gate bias controller to adjust a gate bias of the amplifier based on the envelope signal, a predistortion controller to predistort the input signal based on the envelope signal, based on the adjusted drain bias, and based on the adjusted gate bias, and to output the predistorted signal, and an amplifier to receive the predistorted signal and to generate an amplified output signal from the predistorted signal. The device may be selectable to operate in a linear mode or a nonlinear mode. The nonlinear mode may be selected by applying a large gate offset bias.

Abstract: A device may include an envelope detector to generate an envelope signal from the input signal, a drain bias controller to adjust a drain bias of the amplifier based on the envelope signal, a gate bias controller to adjust a gate bias of the amplifier based on the envelope signal, a predistortion controller to predistort the input signal based on the envelope signal, based on the adjusted drain bias, and based on the adjusted gate bias, and to output the predistorted signal, and an amplifier to receive the predistorted signal and to generate an amplified output signal from the predistorted signal. The device may be selectable to operate in a linear mode or a nonlinear mode. The nonlinear mode may be selected by applying a large gate offset bias.

Abstract: A power amplifier circuit for a mobile terminal controls the bias voltage depending on the modulation of the input signal. The power amplifier circuit includes a power amplifier control circuit configured to control power amplifier bias for a first input signal modulation using calibrated bias control values corresponding to a range of transmit power levels, and to control power amplifier bias for said second input signal modulation using adjusted bias control values obtained by adding bias offsets to said calibrated bias control values.

Abstract: A transmit power amplifier of a wireless terminal is controlled by determining a power supply voltage applied to the transmit power amplifier, determining a power supply current provided to the transmit power amplifier, determining a relationship of the determined power supply current and the determined power supply voltage, and controlling the power supply voltage responsive to the determined relationship of the power supply current and the power supply voltage. For example, determining a relationship of the determined power supply current and the determined power supply voltage may include determining whether the power supply current meets a predetermined criterion, e.g., a predetermined current range, associated with the determined power supply voltage. The invention may be embodied as apparatus, methods, and computer program products.

Abstract: A dual band transceiver for operating in a first lower frequency band such as the band allocated to cellular systems, and in a second higher frequency band such as the band allocated to personal communication services (PCS) systems. In a representative embodiment, the dual band transceiver comprises a main voltage controlled oscillator (VCO) for generating a local oscillator (LO) signal; an offset VCO for generating an offset frequency (OF) signal; a first mixer for combining the LO signal with the OF signal to produce a first transmit signal; a modulator for modulating the first transmit signal with the data signal to produce a first data modulated transmit signal; and a second mixer for combining the first data modulated transmit signal with the LO signal to produce a second data modulated signal. The main VCO and the offset VCO can be programmed such that the first data modulated transmit signal is in the first band and the second data modulated transmit signal is in the second band.

Abstract: An output stage (418) for an operational amplifier (403) powered by a first supply voltage rail (102) and a second supply voltage rail (104) includes a buffer (100) and a current booster (500) for amplifying an input voltage (105) into a low impedance output signal (117 and 520). The buffer (100) amplifies the input voltage (105) into the amplified output signal (117 and 520) when the input voltage (105) is within a buffer voltage range (210), the buffer voltage range (210) contained within a maximum voltage range (208) defined by a voltage difference in the first supply voltage rail (102) and the second supply voltage rail (104). The current booster (500) assists the buffer (100) in amplifying the input voltage (105) into the output signal (117 and 520) when the input voltage (105) is outside of the buffer voltage range (210) but within the maximum voltage range (208).