Abstract: Peak voltage limiting circuits and method for power amplifiers. A power amplifier and/or a voltage limiting circuit includes a diode circuit coupled to an output of an amplification stage, the diode circuit configured to provide a conductive path from the output when an output voltage exceeds a selected value. The power amplifier and/or voltage limiting circuit also includes a sink circuit coupled to the diode circuit and a bias circuit, the sink circuit configured to reduce a bias voltage provided by the bias circuit when the output voltage exceeds the selected value to thereby limit the output voltage.

Abstract: Peak voltage limiting circuits and method for power amplifiers. A power amplifier and/or a voltage limiting circuit includes a diode circuit coupled to an output of an amplification stage, the diode circuit configured to provide a conductive path from the output when an output voltage exceeds a selected value. The power amplifier and/or voltage limiting circuit also includes a sink circuit coupled to the diode circuit and a bias circuit, the sink circuit configured to reduce a bias voltage provided by the bias circuit when the output voltage exceeds the selected value to thereby limit the output voltage.

Abstract: A coupler is presented that has high-directivity and low coupling coefficient variation. The coupler includes a first trace with a first edge substantially parallel to a second edge and substantially equal in length to the second edge. The first trace includes a third edge substantially parallel to a fourth edge. The fourth edge is divided into three segments. The outer segments are a first distance from the third edge. The middle segment is a second distance from the third edge. Further, the coupler includes a second trace, which includes a first edge substantially parallel to a second edge and substantially equal in length to the second edge. The second trace includes a third edge substantially parallel to a fourth edge. The fourth edge is divided into three segments. The outer segments are a first distance from the third edge. The middle segment is a second distance from the third edge.

Abstract: A coupler is presented that has high-directivity and low coupling coefficient variation. The coupler includes a first trace with a first edge substantially parallel to a second edge and substantially equal in length to the second edge. The first trace includes a third edge substantially parallel to a fourth edge. The fourth edge is divided into three segments. The outer segments are a first distance from the third edge. The middle segment is a second distance from the third edge. Further, the coupler includes a second trace, which includes a first edge substantially parallel to a second edge and substantially equal in length to the second edge. The second trace includes a third edge substantially parallel to a fourth edge. The fourth edge is divided into three segments. The outer segments are a first distance from the third edge. The middle segment is a second distance from the third edge.

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: A coupler is presented that has high-directivity and low coupling coefficient variation. The coupler includes a first trace with a first edge substantially parallel to a second edge and substantially equal in length to the second edge. The first trace includes a third edge substantially parallel to a fourth edge. The fourth edge is divided into three segments. The outer segments are a first distance from the third edge. The middle segment is a second distance from the third edge. Further, the coupler includes a second trace, which includes a first edge substantially parallel to a second edge and substantially equal in length to the second edge. The second trace includes a third edge substantially parallel to a fourth edge. The fourth edge is divided into three segments. The outer segments are a first distance from the third edge. The middle segment is a second distance from the third edge.

Abstract: Peak voltage limiting circuits and method for power amplifiers. A power amplifier and/or a voltage limiting circuit includes a diode circuit coupled to an output of an amplification stage, the diode circuit configured to provide a conductive path from the output when an output voltage exceeds a selected value. The power amplifier and/or voltage limiting circuit also includes a sink circuit coupled to the diode circuit and a bias circuit, the sink circuit configured to reduce a bias voltage provided by the bias circuit when the output voltage exceeds the selected value to thereby limit the output voltage.

Abstract: A coupler is presented that has high-directivity and low coupling coefficient variation. The coupler includes a first trace with a first edge substantially parallel to a second edge and substantially equal in length to the second edge. The first trace includes a third edge substantially parallel to a fourth edge. The fourth edge is divided into three segments. The outer segments are a first distance from the third edge. The middle segment is a second distance from the third edge. Further, the coupler includes a second trace, which includes a first edge substantially parallel to a second edge and substantially equal in length to the second edge. The second trace includes a third edge substantially parallel to a fourth edge. The fourth edge is divided into three segments. The outer segments are a first distance from the third edge. The middle segment is a second distance from the third edge.

Abstract: A coupler is presented that has high-directivity and low coupling coefficient variation. The coupler includes a first trace associated with a first port and a second port. The first trace includes a first main arm, a first connecting trace connecting the first main arm to the second port, and a non-zero angle between the first main arm and the first connecting trace. Further, the coupler includes a second trace associated with a third port and a fourth port. The second trace includes a second main arm.

Abstract: Apparatus and methods for wide 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: A coupler is presented that has high-directivity and low coupling coefficient variation. The coupler includes a first trace associated with a first port and a second port. The first port is configured substantially as an input port and the second port is configured substantially as an output port. The coupler further includes a second trace associated with a third port and a fourth port. The third port is configured substantially as a coupled port and the fourth port is configured substantially as an isolated port. In addition, the coupler includes a first capacitor configured to introduce a discontinuity to induce a mismatch in the coupler.

Abstract: A coupler is presented that has high-directivity and low coupling coefficient variation. The coupler includes a first trace with a first edge substantially parallel to a second edge and substantially equal in length to the second edge. The first trace includes a third edge substantially parallel to a fourth edge. The fourth edge is divided into three segments. The outer segments are a first distance from the third edge. The middle segment is a second distance from the third edge. Further, the coupler includes a second trace, which includes a first edge substantially parallel to a second edge and substantially equal in length to the second edge. The second trace includes a third edge substantially parallel to a fourth edge. The fourth edge is divided into three segments. The outer segments are a first distance from the third edge. The middle segment is a second distance from the third edge.

Abstract: A sandwich strip coupled coupler implemented in a multi-layer substrate, such as a multi-layer printed circuit board. In one example, the sandwich strip coupled coupler includes a main arm having a first main arm section and a second main arm section disposed above the first main arm section, the first and second main arm sections being electrically connected together, and a coupled arm disposed between the first and second main arm sections, the first main arm section, the coupled arm and the second main arm section forming a sandwich structure.

Abstract: A coupler is presented that has high-directivity and low coupling coefficient variation. The coupler includes a first trace associated with a first port and a second port. The first trace includes a first main arm, a first connecting trace connecting the first main arm to the second port, and a non-zero angle between the first main arm and the first connecting trace. Further, the coupler includes a second trace associated with a third port and a fourth port. The second trace includes a second main arm.

Abstract: A coupler is presented that has high-directivity and low coupling coefficient variation. The coupler includes a first trace with a first edge substantially parallel to a second edge and substantially equal in length to the second edge. The first trace includes a third edge substantially parallel to a fourth edge. The fourth edge is divided into three segments. The outer segments are a first distance from the third edge. The middle segment is a second distance from the third edge. Further, the coupler includes a second trace, which includes a first edge substantially parallel to a second edge and substantially equal in length to the second edge. The second trace includes a third edge substantially parallel to a fourth edge. The fourth edge is divided into three segments. The outer segments are a first distance from the third edge. The middle segment is a second distance from the third edge.

Abstract: A coupler is presented that has high-directivity and low coupling coefficient variation. The coupler includes a first trace associated with a first port and a second port. The first port is configured substantially as an input port and the second port is configured substantially as an output port. The coupler further includes a second trace associated with a third port and a fourth port. The third port is configured substantially as a coupled port and the fourth port is configured substantially as an isolated port. In addition, the coupler includes a first capacitor configured to introduce a discontinuity to induce a mismatch in the coupler.

Abstract: A sandwich strip coupled coupler implemented in a multi-layer substrate, such as a multi-layer printed circuit board. In one example, the sandwich strip coupled coupler includes a main arm having a first main arm section and a second main arm section disposed above the first main arm section, the first and second main arm sections being electrically connected together, and a coupled arm disposed between the first and second main arm sections, the first main arm section, the coupled arm and the second main arm section forming a sandwich structure.