Abstract: Embodiments described herein relate to an envelope tracking system that uses a single-bit digital signal to encode an analog envelope tracking control signal, or envelope tracking signal for brevity. In certain embodiments, the envelope tracking system can estimate or measure the amplitude of the baseband signal. The envelope tracking system can further estimate the amplitude of the envelope of the RF signal. The system can convert the amplitude of the envelope signal to a single-bit digital signal, typically at a higher, oversample rate. The single-bit digital signal can be transmitted in, for example, a low-voltage differential signaling (LVDS) format, from a transceiver to an envelope tracker. An analog-to-digital converter (ADC or A/D) can convert the single-bit digital signal back to an analog envelope signal. Moreover, a driver can increase the power of the A/D output envelope signal to produce an envelope-tracking supply voltage for a power amplifier.

Abstract: A power amplifier impedance adjustment circuit is disclosed. In one aspect, the impedance adjustment circuit includes an input node configured to receive a radio frequency (RF) signal from a power amplifier, an output node configured to provide the RF signal to an antenna switch die, a plurality of electrical components arranged between the input node and the output node, and at least one switch configured to selectively electrically connect at least one of the electrical components to the input node and the output node. For each state of the at least one switch, the impedance adjustment circuit is configured to adjust an impedance of the power amplifier from a natural tune point in a direction towards a target tuned impedance point when viewed on a Smith chart.

Abstract: A method of adjusting an impedance of a power amplifier of a radio frequency system for matching with an antenna switch die is disclosed. In one aspect, the method includes connecting the power amplifier to the antenna switch die via an impedance adjustment circuit, the impedance adjustment circuit including an input node, an output node, a plurality of electrical components arranged between the input node and the output node, and at least one switch configured to selectively electrically connect at least one of the electrical components to the input node and the output node. The method further includes determining an Error Vector Magnitude of the radio frequency system for each of a plurality of states of the at least one switch, and controlling the at least one switch to enter the state of the plurality of states that minimizes the Error Vector Magnitude of the radio frequency system.

Abstract: A front end module having transmit loopback functionality may be operated by conducting a loopback signal from an output of a power amplifier to a receive port on a transmit loopback path and conducting a radio frequency receive signal from an antenna port to the receive port on a receive path. The transmit loopback path includes a first switch coupled between the output of the power amplifier and the receive port. The receive path includes a second switch coupled between the antenna port, where the receive port and is without the first switch.

Abstract: Embodiments described herein relate to an envelope tracking system that uses a single-bit digital signal to encode an analog envelope tracking control signal, or envelope tracking signal for brevity. In certain embodiments, the envelope tracking system can estimate or measure the amplitude of the baseband signal. The envelope tracking system can further estimate the amplitude of the envelope of the RF signal. The system can convert the amplitude of the envelope signal to a single-bit digital signal, typically at a higher, oversample rate. The single-bit digital signal can be transmitted in, for example, a low-voltage differential signaling (LVDS) format, from a transceiver to an envelope tracker. An analog-to-digital converter (ADC or A/D) can convert the single-bit digital signal back to an analog envelope signal. Moreover, a driver can increase the power of the A/D output envelope signal to produce an envelope-tracking supply voltage for a power amplifier.

Abstract: Embodiments described herein relate to an envelope tracking system that uses a single-bit digital signal to encode an analog envelope tracking control signal, or envelope tracking signal for brevity. In certain embodiments, the envelope tracking system can estimate or measure the amplitude of the baseband signal. The envelope tracking system can further estimate the amplitude of the envelope of the RF signal. The system can convert the amplitude of the envelope signal to a single-bit digital signal, typically at a higher, oversample rate. The single-bit digital signal can be transmitted in, for example, a low-voltage differential signaling (LVDS) format, from a transceiver to an envelope tracker. An analog-to-digital converter (ADC or A/D) can convert the single-bit digital signal back to an analog envelope signal. Moreover, a driver can increase the power of the A/D output envelope signal to produce an envelope-tracking supply voltage for a power amplifier.

Abstract: A front end module having transmit loopback functionality may be operated by conducting a loopback signal from an output of a power amplifier to a receive port on a transmit loopback path and conducting a radio frequency receive signal from an antenna port to the receive port on a receive path. The transmit loopback path includes a first switch coupled between the output of the power amplifier and the receive port. The receive path includes a second switch coupled between the antenna port, where the receive port and is without the first switch.

Abstract: Embodiments described herein relate to an envelope tracking system that uses a single-bit digital signal to encode an analog envelope tracking control signal, or envelope tracking signal for brevity. In certain embodiments, the envelope tracking system can estimate or measure the amplitude of the baseband signal. The envelope tracking system can further estimate the amplitude of the envelope of the RF signal. The system can convert the amplitude of the envelope signal to a single-bit digital signal, typically at a higher, oversample rate. The single-bit digital signal can be transmitted in, for example, a low-voltage differential signaling (LVDS) format, from a transceiver to an envelope tracker. An analog-to-digital converter (ADC or A/D) can convert the single-bit digital signal back to an analog envelope signal. Moreover, a driver can increase the power of the A/D output envelope signal to produce an envelope-tracking supply voltage for a power amplifier.

Abstract: A front end module with transmit loopback functionality has a transmit loopback path that is configured to conduct a loopback signal from an output of a power amplifier to a receive port, and a receive path that is configured to conduct a radio frequency receive signal from an antenna port to the receive port. The transmit loopback path includes a first switch coupled between the output of the power amplifier and the receive port. The receive path includes a second switch coupled between the antenna port and the receive port, where the receive path is without the first switch.

Abstract: A front end module having transmit loopback functionality may be operated by conducting a loopback signal from an output of a power amplifier to a receive port on a transmit loopback path and conducting a radio frequency receive signal from an antenna port to the receive port on a receive path. The transmit loopback path includes a first switch coupled between the output of the power amplifier and the receive port. The receive path includes a second switch coupled between the antenna port, where the receive port and is without the first switch.

Abstract: A method to improve amplifier efficiency of operation relative to that of an amplifier with fixed biasing is operating channel dependent. A bias current for an amplifying transistor of an amplifier circuit is determined based at least in part on an operating channel. The amplifying transistor operates in a multi-channel system, where the bias current for the amplifying transistor operating at channels at an edge of a channel band is different from the bias current for the amplifying transistor operating at channels nearer a center of the channel band.

Abstract: Embodiments described herein relate to an envelope tracking system that uses a single-bit digital signal to encode an analog envelope tracking control signal, or envelope tracking signal for brevity. In certain embodiments, the envelope tracking system can estimate or measure the amplitude of the baseband signal. The envelope tracking system can further estimate the amplitude of the envelope of the RF signal. The system can convert the amplitude of the envelope signal to a single-bit digital signal, typically at a higher, oversample rate. The single-bit digital signal can be transmitted in, for example, a low-voltage differential signaling (LVDS) format, from a transceiver to an envelope tracker. An analog-to-digital converter (ADC or A/D) can convert the single-bit digital signal back to an analog envelope signal. Moreover, a driver can increase the power of the A/D output envelope signal to produce an envelope-tracking supply voltage for a power amplifier.

Abstract: A system improve amplifier efficiency of operation relative to that of an amplifier with fixed biasing is operating channel dependent. A control circuit determines a bias current for an amplifying transistor of an amplifier circuit based at least in part on an operating channel. The amplifying transistor operates in a multi-channel system, where the bias current for the amplifying transistor operating at channels at an edge of a channel band is different from the bias current for the amplifying transistor operating at channels nearer a center of the channel band.

Abstract: A front end module with transmit loopback functionality has a transmit loopback path that is configured to conduct a loopback signal from an output of a power amplifier to a receive port, and a receive path that is configured to conduct a radio frequency receive signal from an antenna port to the receive port. The transmit loopback path includes a first switch coupled between the output of the power amplifier and the receive port. The receive path includes a second switch coupled between the antenna port and the receive port, where the receive path is without the first switch.

Abstract: A front end module having transmit loopback functionality may be operated by conducting a loopback signal from an output of a power amplifier to a receive port on a transmit loopback path and conducting a radio frequency receive signal from an antenna port to the receive port on a receive path. The transmit loopback path includes a first switch coupled between the output of the power amplifier and the receive port. The receive path includes a second switch coupled between the antenna port, where the receive port and is without the first switch.

Abstract: Apparatus and methods for wireless local area network (WLAN) power amplifiers are provided. In certain configurations, a WLAN power amplifier system includes a WLAN power amplifier, an output impedance matching network, and an envelope tracker. The WLAN power amplifier includes an input that receives a WLAN signal having a fundamental frequency and an output that generates an amplified WLAN signal for transmission over an antenna. The output impedance matching network is electrically connected to the output of the WLAN power amplifier, and can provide a load line impedance between 10? and 35? at the fundamental frequency. The envelope tracker receives an envelope of the WLAN signal, and controls a voltage level of a power supply of the WLAN power amplifier based on the envelope signal.

Abstract: Embodiments described herein relate to an envelope tracking system that uses a single-bit digital signal to encode an analog envelope tracking control signal, or envelope tracking signal for brevity. In certain embodiments, the envelope tracking system can estimate or measure the amplitude of the baseband signal. The envelope tracking system can further estimate the amplitude of the envelope of the RF signal. The system can convert the amplitude of the envelope signal to a single-bit digital signal, typically at a higher, oversample rate. The single-bit digital signal can be transmitted in, for example, a low-voltage differential signaling (LVDS) format, from a transceiver to an envelope tracker. An analog-to-digital converter (ADC or A/D) can convert the single-bit digital signal back to an analog envelope signal. Moreover, a driver can increase the power of the A/D output envelope signal to produce an envelope-tracking supply voltage for a power amplifier.

Abstract: A system improve amplifier efficiency of operation relative to that of an amplifier with fixed biasing and fixed matching conditions receives a power level and an indicator of amplifier operation. The indicator is at least one of channel, channel bandwidth, out-of band spectral requirements, spectral mask requirements, error vector magnitude, modulation rate, and modulation type. A controller generates a control signal based at least in part on the power level and the indicator to control at least one of the bias current and the matching conditions of matching circuits. The matching conditions and bias current for channels at an edge of a channel band are different from the bias current and matching conditions for channels nearer a center of the channel band.

Abstract: A system improve amplifier efficiency of operation relative to that of an amplifier with fixed biasing is operating channel dependent. A control circuit determines a bias current for an amplifying transistor of an amplifier circuit based at least in part on an operating channel. The amplifying transistor operates in a multi-channel system, where the bias current for the amplifying transistor operating at channels at an edge of a channel band is different from the bias current for the amplifying transistor operating at channels nearer a center of the channel band.

Abstract: A system improve amplifier efficiency of operation relative to that of an amplifier with fixed biasing and fixed matching conditions receives a power level and an indicator of amplifier operation. The indicator is at least one of channel, channel bandwidth, out-of band spectral requirements, spectral mask requirements, error vector magnitude, modulation rate, and modulation type. A controller generates a control signal based at least in part on the power level and the indicator to control at least one of the bias current and the matching conditions of matching circuits. The matching conditions and bias current for channels at an edge of a channel band are different from the bias current and matching conditions for channels nearer a center of the channel band.