Abstract:
There is described a receiver (1) of at least one radiofrequency modulated signal deriving from an antenna (101) external to the receiver; the receiver comprises a first stage (103) for the low noise amplification of the radiofrequency modulated signal and a demodulation stage (106) of the above-mentioned signal. The receiver comprises a SAW filter (104) adapted to act as a pass band filter about a predetermined frequency for the signal deriving from the first stage, a logarithmic amplifier (105) adapted to amplify the signal deriving from the SAW filter, a peak detector (402) of the output signal of the logarithmic amplifier, means (203) adapted to control the gain of the first stage (103) for the amplification of the radiofrequency modulated signal as a function of the output signal (Vopeak) of the peak detector.
Abstract:
A radio frequency (RF) power amplifier system adjusts the supply voltage provided to a power amplifier (PA) adaptively, responsive to the measured or estimated power of the RF output signal of the PA. The RF PA system includes a power amplifier (PA) which receives and amplifies an RF input signal to generate an RF output signal at a level suitable for transmission to an antenna. A PA supply voltage controller generates a supply voltage control signal, which is used to control the supply voltage to the final stage of the PA. The supply voltage control signal is generated responsive to the measured or estimated power of the PA RF output signal, and also may be responsive to a parameter indicative of impedance mismatch experienced at the PA output. By controlling this supply voltage to the RF PA, the efficiency of the PA is improved.
Abstract:
Improvement of linearity of a transmitter is provided, by a transmission method that includes, when receiving a transmit signal, generating, at a modulation signal generator, a modulation signal modulated from the transmit signal, an average output level and an amplitude with respect to the modulation signal; receiving, at a Read Only Memory (ROM), the average output level and generating a peak amplitude; and generating, at an amplitude shaper, a gain value using the peak amplitude and the amplitude and generating magnitude information by adding an offset value.
Abstract:
A tunable RF filter, comprising: an emitter follower stage (2); and a common emitter stage (4); the common emitter stage (4) providing feedback to the emitter follower stage (2). The common emitter stage (4) may comprise a first transistor (Ti) being the only transistor of the common emitter stage (4); and the emitter follower stage (2) may comprise a second transistor (T2) being the only transistor of the emitter follower stage (2). A further tunable RF filter provides improved linearity, comprising: an emitter follower stage (22); a joint common emitter and emitter follower stage (24); and a gain stage (26); a common emitter output of the joint common emitter and emitter follower stage (24) providing feedback to the emitter follower stage (22), and an emitter follower output of the joint common emitter and emitter follower stage (24) providing an input to the gain stage (26).
Abstract:
Non-linear signal conditioning is provided by signal processing in at least 2 consecutive steps (10). In each step (10) an insertion source signal (41) is provided, which is treated non-linearly to fulfil certain restrictions in bandwidth and/or spectral mask. The insertion signal is combined with a main signal (21) using a reinsertion factor (k 1 -k n ), as a correction of the main signal (21). The reinsertion factor of at least one step is larger than the reinsertion factor of a previous step. In particular embodiments, the reinsertion factor increases for each of the at least 2 steps. This principle can be applied to most non-linear signal processing, and for example in PAR reduction systems, dynamic drain bias PA systems, Doherty and Chireix PA systems and in Dynamic Gate Bias systems.
Abstract:
A power amplifier uses parallel amplification (102, 104 and 106) and at least two levels of power combining (108, 110, 112 and 118) to manage peak-to-peak voltage swings, so as to reduce the likelihood of voltage breakdown at individual transistors. Each level of power combining provides an upward impedance transformation. For example, both levels of power combining may double the impedance output relative to the impedance input, so that the impedance at the amplifier output (114 and 120) is four times the input impedance. For an embodiment in which the second level is a quadrature power combiner (112), load reflections of the amplifier may be terminated at an isolation port (116 and 132). In addition, energy levels of the load reflections may be monitored (144).
Abstract:
The invention relates to a device (12) for amplifying audio signals, comprising an amplifier (121) adapted to receive a first signal as input and to output a second signal capable of powering a loudspeaker (R L ), control means (122) configured for detecting the current and voltage of the second signal and for controlling said amplifier on the basis of the voltage of the first signal and of selection information (k) that allows selecting whether the amplifier (121) is also driven on the basis of the voltage or current of the second signal, tuning means (123) configured for changing the output impedance of the device (12) so that, when the first audio signal has constant frequency and voltage, the voltage of the second signal will be independent of the selection information (k) used by the control means for controlling said amplifier (121).
Abstract:
In an exemplary design, an apparatus (100) includes an amplifier (170), a boost converter (180), and a boost controller (190). The amplifier (170) receives an envelope signal (Venv) and a variable boosted supply voltage (Vboost) and provides an output voltage (Vout) and an output current (lout). The boost converter (180) receives a power supply voltage (Vbat) and at least one signal determined based on the envelope signal (Venv) and generates the variable boosted supply voltage (Vboost) based on the power supply voltage (Vbat) and the at least one signal. The boost controller (190) generates the at least one signal (e.g., an enable signal and/or a threshold voltage) for the boost converter (180) based on the envelope signal (Venv) and/or the output voltage (Vout). The boost converter (180) generates the variable boosted supply voltage (Vboost) based on the power supply voltage (Vbat) and the threshold voltage.