Abstract: High efficiency Doherty amplifiers are described. Contemplated Doherty amplifiers can include an input hybrid coupler having first and second inputs, and first and second drivers that individually drive respective first and second inputs. In this manner, the driver output power to the main and auxiliary amplifiers can be dynamically controlled as a function of an input signal's envelope. This advantageously allows for a substantial decrease in the amount of power wasted by the driver, especially when used with digitally modulated signals.

Abstract: An envelope tracking radio frequency (RF) power amplifier having an adaptive envelope signal processing circuit is disclosed. An RF input voltage is sampled by the adaptive envelope signal processing circuit which provides control signals to the power supply which supplies voltages to RF power devices in order to simultaneously satisfy two operating conditions: a) provide best possible efficiency of the power amplifier stages depending on the input signal characteristics and b) provide compensation for RF transistor AM-AM and AM-PM distortion compensation across the power range. In particular, the voltage control provides for constant power amplifier gain across the input signal dynamic range, thus minimizing power amplifier amplitude distortions and extending the useful power amplifier linear dynamic range up to saturation point. The power amplifier thus exhibits better linearity and efficiency than offered by conventional techniques and topologies.

Abstract: A high efficiency radio frequency (RF) power amplifier having dynamically controlled back off is disclosed. The RF input voltage is sampled by an adaptive analog signal processing circuit. The adaptive analog signal processing circuit controls the supply voltage to RF amplifier devices, such as LDMOS devices, which varies the efficiency or back off of the power amplifier. The variable supply voltage in turn varies peak power of the amplifier.

Abstract: A delay mismatched feed forward power amplifier is disclosed. Loop 1 includes a main amplifier and is used to derive a carrier cancelled sample of the main amplifier output. Loop 2 includes an error amplifier used to amplify the carrier cancelled signal derived from Loop 1 operation in order to cancel distortion products generated due to the nonlinear nature of the main amplifier. Loop 2 also utilizes a very short Loop 2 delay line. A significant efficiency gain is provided due to reduced output power losses associated with the Loop 2 delay line. Lower output losses also results in lower distortion levels produced by the main amplifier. This, in turn, reduces the size and performance requirements placed on the error amplifier. A smaller and more efficient error amplifier is employed resulting in further amplifier system efficiency improvement. The delay mismatch is compensated by a third control loop, a special adaptive control algorithm or a combination thereof.

Abstract: A dual loop feedforward power amplifier. A dual loop feedforward power amplifier, comprising an input that provides a multicarrier signal; a first feedforward power amplifier; and a second feedforward power amplifier, wherein the first feedforward power amplifier serves as a main amplifier gain block in the second feedforward power amplifier, wherein the first feedforward power amplifier comprises a carrier cancellation loop and a first error amplifier loop, and wherein the second feedforward power amplifier comprises a third loop and a fourth loop that cancel small signal distortions that are not reduced by the first feedforward amplifier.

Abstract: A delay mismatched feed forward power amplifier is disclosed. Loop 1 includes a main amplifier and is used to derive a carrier cancelled sample of the main amplifier output. Loop 2 includes an error amplifier used to amplify the carrier cancelled signal derived from Loop 1 operation in order to cancel distortion products generated due to the nonlinear nature of the main amplifier. Loop 2 also utilizes a very short Loop 2 delay line. A significant efficiency gain is provided due to reduced output power losses associated with the Loop 2 delay line. Lower output losses also results in lower distortion levels produced by the main amplifier. This, in turn, reduces the size and performance requirements placed on the error amplifier. A smaller and more efficient error amplifier is employed resulting in further amplifier system efficiency improvement. The delay mismatch is compensated by a third control loop, a special adaptive control algorithm or a combination thereof.

Abstract: A method for aligning a feed forward radio frequency power amplifier includes applying a radio frequency signal to the feed forward radio frequency power amplifier and monitoring a radio frequency signal from the feed forward radio frequency power amplifier, without opening a break point of the feed forward radio frequency amplifier.

Abstract: A group delay adjusting circuit. The group delay adjusting circuit comprises an electronically adjustable variable capacitance, and an electronically variable virtual inductor coupled in parallel to the electronically variable capacitance at a node.

Abstract: A feed forward power amplifier is disclosed which utilizes three signal cancellation loops. Loop 1 includes a main amplifier and is used to derive a carrier cancelled sample of the main amplifier output. Loop 2 includes an error amplifier used to amplify the carrier cancelled signal derived from Loop 1 operation in order to cancel distortion products generated due to the nonlinear nature of the main amplifier. Loop 2 also utilizes a very short Loop 2 delay line. A significant efficiency gain is provided due to reduced output power losses associated with the Loop 2 delay line. Lower output losses also results in lower distortion levels produced by the main amplifier. This, in turn, reduces the size and performance requirements placed on the error amplifier. A smaller and more efficient error amplifier is employed resulting in further amplifier system efficiency improvement.

Abstract: A high efficiency radio frequency (RF) power amplifier having dynamically controlled back off is disclosed. The RF input voltage is sampled by an adaptive analog signal processing circuit. The adaptive analog signal processing circuit controls the supply voltage to RF amplifier devices, such as LDMOS devices, which varies the efficiency or back off of the power amplifier. The variable supply voltage in turn varies peak power of the amplifier.

Abstract: A feedforward amplifier. The present invention therefore provides a feedforward amplifier, comprising: a pilot reference generator that generates a pilot signal; a first carrier cancellation loop; a first error amplifier loop including a first error amplifier, wherein the pilot signal is utilized to provide gain stabilization in the first error amplifier a third loop; a second carrier cancellation loop that includes a first phase and amplitude adjuster in module and a second amplitude and phase adjuster disposed between module and module, wherein the pilot signal is utilized to control the adjustment of the second carrier cancellation loop.

Abstract: An envelope tracking radio frequency (RF) power amplifier having an adaptive envelope signal processing circuit is disclosed. An RF input voltage is sampled by the adaptive envelope signal processing circuit which provides control signals to the power supply which supplies voltages to RF power devices in order to simultaneously satisfy two operating conditions: a) provide best possible efficiency of the power amplifier stages depending on the input signal characteristics and b) provide compensation for RF transistor AM-AM and AM-PM distortion compensation across the power range. In particular, the voltage control provides for constant power amplifier gain across the input signal dynamic range, thus minimizing power amplifier amplitude distortions and extending the useful power amplifier linear dynamic range up to saturation point. The power amplifier thus exhibits better linearity and efficiency than offered by conventional techniques and topologies.

Abstract: A microstrip coupler is provided which includes an controlled capacitance bridge for improved directivity as compared to prior art controlled capacitance bridges. The novel controlled capacitance bridge provides the functionality of prior art wire or ribbon controlled capacitance bridges and also provides the necessary capacitance to compensate for the different phase velocities of odd and even modes in the transmission lines. Both the dimensions of the controlled capacitance bridge and the dimensions of an input microstrip conductor may be adjusted to provide the appropriate level of capacitance. In some embodiments, the controlled capacitance bridge connects segments of an input microstrip conductor. In other embodiments, the controlled capacitance bridge connects microstrip conductors which are configured to couple an input signal from an input microstrip conductor.

Abstract: A system and method of pilot tone reuse.

Abstract: A dynamic bias switching circuit is provided that includes a switching unit for switching between a first signal level and a second signal level based on a signal envelope of an input signal to an amplifier.

Abstract: A dual loop feedforward power amplifier. A dual loop feedforward power amplifier, comprising an input that provides a multicarrier signal; a first feedforward power amplifier; and a second feedforward power amplifier, wherein the first feedforward power amplifier serves as a main amplifier gain block in the second feedforward power amplifier, wherein the first feedforward power amplifier comprises a carrier cancellation loop and a first error amplifier loop, and wherein the second feedforward power amplifier comprises a third loop and a fourth loop that cancel small signal distortions that are not reduced by the first feedforward amplifier.

Abstract: A system and method of pilot tone reuse.

Abstract: A feedforward amplifier. The present invention therefore provides a feedforward amplifier, comprising: a pilot reference generator that generates a pilot signal; a first carrier cancellation loop; a first error amplifier loop including a first error amplifier, wherein the pilot signal is utilized to provide gain stabilization in the first error amplifier a third loop; a second carrier cancellation loop that includes a first phase and amplitude adjuster in module and a second amplitude and phase adjuster disposed between module and module, wherein the pilot signal is utilized to control the adjustment of the second carrier cancellation loop.

Abstract: A group delay adjusting circuit. The group delay adjusting circuit comprises an electronically adjustable variable capacitance, and an electronically variable virtual inductor coupled in parallel to the electronically variable capacitance at a node.

Abstract: A method for aligning a feed forward radio frequency power amplifier includes applying a radio frequency signal to the feed forward radio frequency power amplifier and monitoring a radio frequency signal from the feed forward radio frequency power amplifier, without opening a break point of the feed forward radio frequency amplifier.