Maxim Integrated Products, Inc.

Joel R King

Gordon Alan Olsen

Prasad Yenigalla

The present invention teaches a power amplifier having two or more output power devices and a combining network for switching the output path between these several power devices. The first output power device is designed for power efficient signal amplification at the power amplifier's highest output power level. The second output power device is designed for power efficient signal amplification at the output power level that the power amplifier is most likely to operate. Either the first or second output power device is enabled depending on the output power level. A combining network is used to transform the output impedance, as required, for the proper operation of the enabled power device. By switching between a range of power devices according to the output power level, a high level of power efficiency can be achieved across a broad range of operating states of the power amplifier.

Combining networks for switchable path power amplifiers

The present invention teaches a power amplifier having two output power devices and a mechanism for switching the output path between these two power devices. The first output power device is designed for power efficient signal amplification at the power amplifier's highest output power level. The second output power device is designed for power efficient signal amplification at the output power level that the power amplifier is most likely to operate. By switching between the two power devices according to the output power level, a high level of power efficiency can be achieved across a broad range of operating states of the power amplifier.

Switchable path power amplifier with combining network

A cascaded amplifier is integrated within an integrated circuit with a cascaded ground bus. The cascaded ground bus provides two ground points at opposite ends. Each amplifier ground of each amplifier stage couples to the ground wire there between. The cascaded ground bus substantially reduces the parasitic inductance in the emitter leg of each IC transistor within each amplifier. The lay out of the cascaded ground bus wire is tightly coupled to the lay out of the input wires so that their respective parasitic inductances are magnetically coupled together to form a mutual inductance. The mutual inductance effectively cancels the effect of the ground return inductance due to them being similar inductance values and having the same ground loop current flowing through them in opposite directions. The cascaded ground bus can be utilized in substantially all amplifier types including class A, B, C, D, BD, E, F, G, H, S and their variations and with substantially all transistor types used within amplifier stages including bipolar junction transistors, field effect transistors and their variants (i.e. PNP, NPN, MOSFET, NFET, PFET, JFET, MESFET, etc.). An IC cascaded amplifier with the cascaded ground bus can be utilized in a number of communication systems where amplification is needed including battery operated systems such as a transceiver of a portable cellular telephone.

Method and apparatus for cascaded ground return amplifier

Switchable path power amplifier with schotky diode combining network

The present invention teaches a variety of high VSWR mismatch output stages and methods for protecting output stages during high VSWR operation. To accomplish these goals, the present invention teaches absorbing reverse base current arising at the base of the power transistor of the output stage. In one embodiment, a variable impedance device such as a transistor is coupled to the base of the power transistor such that when the base-emitter voltage exceeds a predefined voltage, the variable impedance device goes into a low impedance mode and absorbs a portion of the base current. In another embodiment, feedback control circuitry is incorporated into the output stage bias circuitry in order to control the total base current.

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Hillsboro, OR, United States of America

Joel R King