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 arrangement (1000) for use in an RF communication terminal including a plurality of resonators (1003, 1005, 1007, 1009) formed from a plurality of conducting wires (1002, 1004, 1008, 1010, 1012) the resonators being operable to provide radio frequency resonances in at least two different operational frequency bands (VHF, UHF, 700/800 MHz, GPS ranges) the wires being mutually adjacent and at least three of the wires having different lengths, and a plurality of radio frequency feed channels (113, 115, 117, 119) each being operably connected to an associated one of the resonators to deliver an RF signal between that resonator and an associated radio.
Abstract:
A terminal (200) and method for operation thereof for use in a wireless communication system (100), the terminal including a plurality of antennas (215, 235, 255) and a plurality of receiver chains (217, 237, 257) each including an associated one of the antennas, the terminal being operable to receive a signal including a plurality of time divided portions including a first portion (303) and a second portion (304), characterised in that the terminal is operable in a manner such each of the plurality of receiver chains is active when the first portion of the signal is being received and at least one of the receiver chains is inactive when the second portion of the signal is being received.
Abstract:
In accordance with the present invention there is those provided a Cartesian loop transmitter having an isolator eliminator circuitry comprising a set of low pass and band pass filters for each of an I- and Q-channels, root mean square detectors and a divider connected to a comparator are received by a microprocessor which controls attenuation setting. There is also provided a method of adjusting an output level of such transmitter. Said method comprises the step of measuring an on-channel signal level and a noise level and then calculating a ratio of said noise to said on-channel signal. If the ratio exceeds a defined threshold an attenuation of the input attenuators is increased.
Abstract:
A wireless communication unit (300) comprises a frequency generation circuit, and a linearised transmitter (325) operably coupled to the frequency generation circuit and having a forward path for routing a signal to be transmitted; and a feedback path, operably coupled to a power amplifier (324) and the forward path for feeding back a portion of the signal to be transmitted. The feedback path and forward path form two loops in quadrature. The frequency generation circuit comprises independent phase shift elements arranged to independently phase shift the two loops in quadrature ('I' and 'Q').
Abstract:
A Cartesian loop transmitter having isolator eliminator circuitry is presented. The isolator eliminator circuitry includes a set of low pass and wide band pass as well as narrow band pass filters for each of I- and Q-channels, root mean square detectors and dividers connected to a means for comparing. Signals from the means for comparing are received by a microprocessor which controls attenuation setting. The output level of the transmitter is adjusted by generating a small signal measuring an on-channel signal level and a small signal level and then calculating a ratio of the small signal to the on-channel signal. The attenuation setting is increased if the ratio exceeds a defined threshold.