Coolstar Technology, Inc.

Wenhua Dai

Shuming Xu

A method of integrating at least one passive component and at least one active power device on a same substrate includes: forming a substrate having a first resistivity value associated therewith; forming a low-resistivity region having a second resistivity value associated therewith in the substrate, the second resistivity value being lower than the first resistivity value; forming the at least one active power device in the low-resistivity region; forming an insulating layer over at least a portion of the at least one active power device; and forming the at least one passive component on an upper surface of the insulating layer above the substrate having the first resistivity value, the at least one passive component being disposed laterally relative to the at least one active power device and electrically connected with the at least one active power device.

Integration of active power device with passive components

An RF PA is designed to operate efficiently for average powers when biased at the system supply voltage, and uses an envelope tracking power supply to boost the bias voltage to maintain good efficiency at higher powers. As a result, for a majority of the time when transmitting average power signals, the RF PA bias voltage is the system-wide supply voltage (e.g. 3.4V in cell phones), which eliminates the need for stepping down voltages. The bias voltage is boosted during the less frequent times when higher power is needed. As a result, only a boost type of DC voltage converter is needed. The efficiency of the RF PA is therefore increased because voltage conversion is required less frequently and only when higher power RF signals are transmitted.

Adaptive envelope tracking for biasing radio frequency power amplifiers

An LDMOSFET is designed with dual modes. At the high voltage mode, it supports a high breakdown voltage and is biased at a high voltage to get the benefits of high output power, higher output impedance and lower matching loss. At the low voltage mode, it exhibits a reduced knee voltage so that some extra voltage and power can be gained although it is biased at lower voltage. The efficiency is therefore improved as well.

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Wenhua Dai