Integrated Ultra-Compact VSWR Insensitive Coupler

Abstract

A ultra-compact coupler designed to sample the actual output power of a power amplifier and which is “VSWR insensitive”, such that reflected power is essentially not coupled to a detector circuit and only forward power is detected and processed. In a first embodiment, a coupler is situated between the final amplifier stage of a power amplifier and an output impedance matching network, and is specially configured for operation in a low impedance environment in conjunction with a detector circuit, thereby substantially reducing the areal size of the coupler. In a second embodiment, a coupler is integrated within an output impedance matching network coupled to the final amplifier stage of a power amplifier so as to share an inductor between the coupler and the output impedance matching network, thereby further substantially reducing the areal size of the coupler.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This invention may be related to U.S. patent application Ser. No. 15 / 594,336 (Attorney Docket No. PER-220-PAP), filed May 12, 2017, entitled “Compact Low Loss Signal Coupler”, assigned to the assignee of the present invention and hereby incorporated by reference.BACKGROUND(1) Technical Field[0002]This invention relates to electronic circuits, and more particularly to coupler circuits.(2) Background[0003]Power amplifiers (PAs) are used in a multitude of electronic systems, particularly radio frequency (RF) systems such as radios, cellular telephones, WiFi, etc. FIG. 1 is a block diagram of a prior art radio transmitter two-stage power amplifier 100. In the illustrated example, an integrated circuit (IC) 102 includes several subcircuits that accept an RF input signal RFIN and generate an amplified output signal RFOUT to a selected destination (e.g., one or more band filters, RF signal switches, and / or antennas); the IC 102 may also be refer...

AI Technical Summary

Benefits of technology

[0008]In a first embodiment, a coupler is situated between the final amplifier stage of a power amplifier and an output impedance matching network, and is specially configured for operation in a low impedance environment in conjunction with a detector circuit, thereby substantially reducing the areal size of the coupler.

[0009]In a second embodiment, a coupler is integrated within an output impedance matching network coupled to the final amplifier stage of a power amplifier so as to share an inductor between the coupler and the output impedance matching network, thereby further substantially reducing the areal size of the coupler.

Problems solved by technology

A problem with that solution is that reflected power, such as from an antenna, is also coupled into the power detector, causing the power detector to exhibit a sensitivity to the voltage standing wave ratio (VSWR) that exists at the output of the final amplifier stage 110 (VSWR is essentially the ratio of “reflected power” to “forward power”).

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