Abstract:
An integrated circuit includes a linearizer circuit in which excessive delay is compensated. The linearizer circuit includes a power amplifier, forward and feedback paths, and a microprocessor. A signal from the power amplifier is routed by the forward path to be transmitted while a portion of the signal to be transmitted is routed back to the power amplifier via the feedback path. The microprocessor applies phase training signals to the forward path. The microprocessor uses the phase training signals to determine the amount of delay in the linearizer circuit and alters the frequency position of poles and zeros in the linearizer circuit to compensate for the delay. The gain of the linearizer circuit is also altered by the microprocessor depending on the measured delay.
Abstract:
A communication device, transmitter, and system containing dual quadrature phase shifters and method of training the transmitter are provided. During training, a phase training module determines the phase imbalance in each of in-phase and quadrature Cartesian feedback paths. The phase training module provides control signals to each of in-phase and quadrature dual phase shifters to provide separate and independent phase corrections for the paths. During one training cycle, individual sessions are used to train the in-phase and quadrature dual phase shifters. The latter session uses the results of the former session to provide an initial value for the phase shift to be provided as a result of the latter session, thereby reducing the overall time used to train both the in-phase and quadrature dual phase shifters.
Abstract:
A linear RF transmitter (100) includes a forward path (102, 105, 107) for receiving and processing a baseband input signal, the forward path including an upconverting mixer (120, 122) operable to convert a baseband signal into a modulated RF signal, and a RF (radio frequency) power amplifier (126) operable to amplify a modulated RF signal produced by the mixer, a non-linearity detector (125) connected to the forward path to sample a baseband signal for delivery to the mixer and operable to detect non-linearity of the transmitter and to provide in response a control signal to change operation of the transmitter to reduce the non-linearity, and characterised in that the transmitter further includes a regulator (111) connectible to a supply voltage source (113) and to the RF power amplifier to deliver a variable supply voltage (VS) to the RF power amplifier and a controller (127) operable to produce a control signal which controls adjustment by the regulator (111) of the supply voltage, wherein the non-linearity detector is connected to the controller and is operable upon detecting non-linearity to deliver a control signal to the controller which causes the controller to adjust the regulator to increase the supply voltage. Also described is a method of operation (200) in the transmitter.
Abstract:
An antenna and methods for manufacturing the antenna is provided. The antenna (100) includes an electrically non-conductive substrate (102). The antenna further includes an electrically conductive strip (104). The electrically conductive strip (104) is wound around the electrically non-conductive substrate (102) so as to form an overlap (120) between adjacent turns of the electrically conductive strip (104), without creating a galvanic connection at the overlap.
Abstract:
An RF receiver (100) including an RF amplifier (105) for amplifying a received input RF signal, a mixer (107) for converting an RF signal produced as an output by the RF amplifier to a baseband signal, a baseband receiver channel (115) for processing the baseband signal, the baseband receiver channel including a baseband amplifier (127), an AGC (automatic gain control) loop (130) coupled from the baseband receiver channel to the RF amplifier to provide automatic gain control of the RF amplifier, an off-channel detector (163) operable to detect activation of the AGC loop by an unwanted received off-channel signal and a control loop (145) coupled from the detector to the baseband amplifier (127) to apply a control signal to the baseband amplifier to reduce a gain of the baseband amplifier when the off-channel detector detects an unwanted received off-channel signal. Also described is a wireless communication terminal and a method of operation in the receiver.
Abstract:
A wireless receiver comprising an input signal path (101), a circuit (113) for producing in-phase and quadrature components, and an estimator (204) for periodically estimating an imbalance in amplitude between the in-phase and quadrature components and for applying a relative adjustment in amplitude to compensate for the detected imbalance, wherein the estimator (204) is operable (i) to divide samples I i of the in-phase component I(t) and corresponding samples Q i of the quadrature component Q(t) into blocks; (ii) to calculate for each block, a block power value I n corresponding to a summation of values of squares of the samples I n; (iii) to calculate from the block power values I n and Q n a block amplitude imbalance value (see above formula); and (iv) to calculate for a set of the block amplitude imbalance values an average value.