摘要:
An amplifier circuit includes a power amplifier biased for saturated mode operation, and a controllable current source to provide supply current to the power amplifier. The controllable current source effects desired amplitude modulation of the output signal from the power amplifier by modulating the supply current it provides responsive to an amplitude information signal. In one or more embodiments, the current source includes a circuit that is configured to adjust one or more transmitter operating parameters responsive to detecting changes in the effective DC resistance of the power amplifier. For example, the circuit may generate a compensation signal that reduces the effective DC resistance responsive to detecting that the effective DC resistance has undesirably increased. By way of non-limiting examples, such compensation may be effected by changing a current mirror, an amplifier-to-antenna impedance matching, an amplifier bias or device size, or imposing some form of transmit signal back-off.
摘要:
Power amplifiers having reactive networks (such as classes C, C-E, E and F) employ tunable reactive devices in their reactive networks, with the reactive devices respective reactance values capable of being adjusted by means of respective control signals. The tunable reactive devices are made from micro-electromechanical (MEM) devices capable of being integrated with the control circuitry needed to produce the control signals and other amplifier components on a common substrate. The reactive components have high Q values across their adjustment range, enabling the amplifier to produce an output with a low harmonic content over a wide range of input signal frequencies, and a frequency agile, high quality output. The invention can be realized on a number of foundry technologies.
摘要:
An integrated, variable gain microwave frequency power amplifier comprises a number of individual amplifier stages which contain microwave frequency active devices. Each stage is fed with a common input signal, and the individual stage outputs are connected to respective micro-electromechanical (MEM) switches which, when closed, connect the individual outputs together to form the power amplifier's output. The power amplifier's gain is determined by the number of outputs connected together. The preferred switch provides low insertion loss and excellent electrical isolation, enabling a number of amplifier stages to be efficiently interconnected to provide a wide dynamic range power amplifier. The switches are preferably integrated on a common substrate with the active devices, eliminating the need for wire bonds and reducing parasitic capacitances. A variable impedance network comprising a number of impedance matching networks selected using MEM switches can be connected to and integrated with a variable gain power amplifier to provide impedance matching that is appropriate for each of the power amplifier's possible output power levels.
摘要:
Embodiments of the present invention provide methods and systems for current sensing for an amplifier using an embedded cell. The embedded cell is a transistor cell from a plurality of transistor cells which is coupled to the other transistor cells so as to block DC current flow between the embedded cell and the other cells and allow AC current to flow between the embedded cell and the other cells. Power may be supplied to the embedded cell through a current sensing circuit, such as a resistor, which senses the DC current drawn by the embedded cell which reflects to the total DC current drawn by the by amplifier. Systems for bias control and for amplitude modulation utilizing embedded cells are also provided.
摘要:
A high-Q precision integrated reversibly trimmable singleband oscillator and tunable multiband oscillator are presented that overcome the problems laser trimming and solid state switches. This is accomplished using micro-electromechanical system (MEMS) technology to integrate an amplifier and its tunable LC network on a common substrate. The LC network can be configured to provide a very narrow bandwidth frequency response which peaks at one or more very specific predetermined frequencies without de-Qing the oscillator.
摘要:
An apparatus for monitoring a power amplifier coupled to a transmission medium includes a detector circuit, coupled to the transmission medium, that generates first and second detector signals corresponding to respective fundamental and harmonic components of a power amplifier output signal produced by the power amplifier. A comparing circuit is coupled to the detector circuit and compares the first and second detector signals. The comparing circuit, responsive to a comparison of the first and second detector signals, may generate a signal that indicates linearity of the power amplifier. In some embodiments, the detector circuit may generate the second detector signal without requiring phase information for the harmonic component. In other embodiments, a control circuit controls linearity of the power amplifier responsive to comparison of the first and second detector signals, for example, by controlling power amplifier bias and/or input signal level based on the comparison. Related methods are also discussed.
摘要:
A radio frequency power amplifier circuit provides linear amplitude modulation of a radio frequency output signal while operating in a saturated amplification mode. The power amplifier circuit incorporates a lossy modulator that functions as a variable resistance responsive to an amplitude modulation signal. A supply voltage is coupled to the voltage supply input of the power amplifier circuit through the lossy modulator, such that the supply voltage applied to the power amplifier varies with the amplitude modulation signal. The radio frequency power amplifier circuit modulates the envelope of an RF output signal generated by saturated mode amplification of a constant envelope radio frequency input signal.
摘要:
A apparatus for providing a waveform as a switched input into an output matching network of a standard class E amplifier. The apparatus includes a switch in communication with the input and the combining device receiving amplitude and phase information from the primary waveform. The combining device functions to combine the amplitude and phase information to create a control signal which is used to control the switch and create a secondary waveform for input to the matching network. In this way, an amplitude modulated waveform is amplified at high efficiency, enabling application of either all or part of the phase and/or amplitude modulation at the input of the amplifier.
摘要:
A frequency stabilizer circuit in the form of a charge-pump phase-lock loop utilizing a MEMS capacitance device, preferably a tunable MEMS capacitor or a MEMS capacitor bank, which more rapid and with a greater precision determine the phase and frequency of a carrier signal so that it can be extracted, providing an information signal of interest. Such MEMS devices have the added advantage of providing linear capacitance, low insertion losses, higher isolation and high reliability, they run on low power and permit the entire circuit to be fabricated on a common substrate. The use of the MEMS capacitance device reduces unwanted harmonics generated by the circuit's charge pump allowing the filtering requirements to be relaxed or perhaps eliminated.
摘要:
A high-performance integrable tunable inductor includes a "primary" coil and a "drive" coil placed in close proximity to each other and simultaneously driven with primary and drive currents, respectively. The drive current induces mutual components of inductance in the primary coil which vary with the phase and amplitude relationship between the two currents. These relationships are controlled to precisely establish the impedance of the primary coil, allowing the inductor to be "tuned" to provide a desired inductance or resistance by simply varying the phase and amplitude relationships appropriately. Inductance values tunable over ranges of about 2:1 and Q values of nearly 2000 have been demonstrated. The primary coil can also be made to operate as a relatively large integrated capacitance by setting the phase and amplitude relationships appropriately. The tunable inductor can be fabricated with standard CMOS processes, or any of a number of other processing technologies, and thus integrated into a host of analog circuits for which a highly-integrated implementation is desirable.