摘要:
A system for saturation detection and compensation in a power amplifier includes a power amplifier, a closed power control loop configured to develop a power control signal (VPC), a comparator configured to receive the power control signal and a reference signal, the comparator also configured to determine whether the power amplifier is operating in a saturation mode, and power control circuitry configured to reduce the power control signal if the power amplifier is operating in a saturation mode.
摘要:
A single continuous closed-loop power control feedback system provides seamless power control for a power amplifier and also enables an AM signal to be injected into the power amplifier through the power amplifiers' control port. The AM signal is developed by an I/Q modulator and supplied to a comparator located in the power control loop. By using leakage from the power amplifier as feedback to a phase locked loop during initial power amplifier power ramp-up, the single continuous closed-loop power control system provides continuous feedback to the phase locked loop during the entire power amplification ramp-up period and eliminates the need for multiple feedback loops.
摘要:
A direct conversion receiver system is provided in which a first input signal at a first frequency is applied to a first input port of a multiplier, a second input signal at a second frequency equal to about {fraction (1/n)} times the first frequency, wherein n is an integer, is applied to a second input port of the multiplier. A first filter coupled to the first input port is configured to substantially filter out any leakage at the second frequency which may be present. A second filter coupled to the second input port is configured to substantially filter out any leakage at the first frequency which may be present. The multiplier is configured to produce a signal at an output port thereof which is derived from the product of the first and second signals. In one embodiment, the output is representative of the product of the filtered first signal and a multiplication factor which switches at n times the second frequency. The output of the multiplier is coupled to a third filter. The output signal has a baseband component and another component. The third filter is configured to substantially filter out the other component and substantially maintain the baseband component in the output signal. In one implementation example, the multiplier is a mixer initializing half-frequency injection, such that the LO frequency is about ½ the RF frequency.
摘要:
A method for a closed power control feedback loop allows a single portable transceiver architecture to be used for systems in which a transmit signal including both a phase modulated (PM) component and an amplitude modulated (AM) component are supplied to a power amplifier and in systems in which the transmit signal has only a PM component supplied to a power amplifier. By injecting the inverse of the AM portion of the desired transmit signal into the closed power control feedback loop, the feedback loop will not cancel the AM portion of the signal, thus allowing a system where both a PM component and an AM component of the transmit signal are present at the output of the power amplifier to function using a closed power control feedback loop.
摘要:
A mirror translation loop upconverter that is capable of upconverting both constant envelope and non-constant envelope modulation formats is disclosed. Embodiments of the invention provide the ability to upconvert a transmit signal that includes only a phase-modulated component, only an amplitude-modulated component, or both a phase-modulated component and an amplitude-modulated component. If the transmit signal includes both a phase-modulated signal component and an amplitude-modulated signal component, the phase-modulated signal component and the amplitude-modulated signal component are supplied to a pair of phase shifters. The phase shifters alter the phase of the phase-modulated signal by an amount related to the amplitude of the amplitude-modulated signal. The phase shifters oppositely alter the phase of the phase-modulated signal, and therefore supply complementary phase versions of the phase-modulated signal. The phase-altered phase-modulated signals from the phase shifters are then supplied to a pair of translation loops. The translation loops are arranged in mirror architecture so that each translation loop receives the phase-altered phase-modulated signals. Each translation loop upconverts the signals and supplies a vector. The vectors supplied by the two translation loops are constant in magnitude, and have complementary phase. The two vectors are added together to provide a signal to a power amplifier. The signal represents both the phase and amplitude information to be transmitted.
摘要:
A translation loop modulator and power amplifier in a phase and amplitude modulated transmission environment includes a translation loop having a phase locked loop and that is configured to receive a first modulated signal (PM) and that is also configured to provide a frequency specific modulated signal. The invention also includes a power amplifier configured to receive the frequency specific modulated signal, a variable gain element configured to provide a second modulated signal (AM) to the power amplifier and a switching element configured to receive a portion of an output of the translation loop and a portion of an output power of the power amplifier. The switching element is configured to apply the output portion of the translation loop to an input of the translation loop during a first time period and apply the detected output power portion of the power amplifier to the input of the translation loop during a second time period, thus allowing the phase locked loop in the translation loop to correct for any phase shift caused by the power amplifier.
摘要:
A system for a closed power control feedback loop allows for the use of a non-linear amplifier for amplifying a phase modulated (PM) signal while introducing an inverse version of the desired amplitude modulated (AM) signal into the feedback loop using a variable gain element. By introducing an inverse version of the desired AM portion of the signal into the power control feedback loop, the non-linear, and highly efficient, power amplifier may be used to amplify only the PM portion of the signal, while the AM portion is introduced by the power control feedback loop. In another aspect of the invention, an inverse version of the AM portion of the desired transmit signal is introduced into the power control feedback loop of an amplifier that is amplifying both a phase modulated signal and an amplitude modulated signal. By introducing an inverse version of the desired AM signal into the power control feedback loop, the power control feedback loop may not cancel the AM component present at the output of the power amplifier. In yet another aspect of the invention, the desired AM signal is injected into the feedback loop along with the power control reference signal.
摘要:
A closed loop power control system for a radio frequency (RF) transmitter comprises a first variable gain element located in a power control loop and configured to receive a power level signal and an inverse representation of a power control signal, a second variable gain element located in the power control loop and configured to receive an error signal and the power control signal, and a third variable gain element configured to receive an amplitude modulated (AM) signal and the power control signal, the third variable gain element having a gain characteristic configured to operate to reduce the gain applied to the AM signal when the power control signal falls below a minimum predetermined value, and to provide the AM signal as a reference signal.
摘要:
A single continuous closed-loop power control feedback system provides seamless power control for a power amplifier and also enables an AM signal to be injected into the power amplifier through the power amplifiers' control port. The AM signal is developed by an I/Q modulator and supplied to a comparator located in the power control loop. By using leakage from the power amplifier as feedback to a phase locked loop during initial power amplifier power ramp-up, the single continuous closed-loop power control system provides continuous feedback to the phase locked loop during the entire power amplification ramp-up period and eliminates the need for multiple feedback loops.
摘要:
A closed loop power control system for a radio frequency (RF) transmitter comprises a first variable gain element located in a power control loop and configured to receive a power level signal and an inverse representation of a power control signal, a second variable gain element located in the power control loop and configured to receive an error signal and the power control signal, and a third variable gain element configured to receive an amplitude modulated (AM) signal and the power control signal, the third variable gain element having a gain characteristic configured to operate to reduce the gain applied to the AM signal when the power control signal falls below a minimum predetermined value, and to provide the AM signal as a reference signal.