Patent Grant
10177721
Radio frequency (RF) power amplifiers are sometimes subjected to input RF overdrive conditions, typically during a calibration procedure for cell phone applications. This overdrive condition can be destructive depending on other factors such as supply voltage and output load voltage standing wave ratio (VSWR).
A limiter circuit is integrated into an RF power amplifier. The limiter circuit automatically starts adding attenuation at the input of the RF power amplifier after a predetermined input power level threshold is exceeded, thereby extending the safe input drive level to protect the amplifier. In a preferred embodiment of the invention, the limiter circuit is implemented using a pseudomorphic high electron mobility transistor (PHEMT) device or a metal semiconductor field effect transistor (MESFET) device. Diode connected transistors or Schottky diodes may also be used in the limiter circuit.
These and other objects, features and advantages of the invention will be more readily apparent from the following detailed description in which:
With RF applied to “RFIN” in the normal operational input power range, M2 is biased to be in a fully on low loss state. When the input level reaches a certain power level determined by the combination of the diodes, resistors and the RF gain of the first stage (Q6), the source and drain voltage of M2 will increase to become more positive relative to the gate causing M2 to start pinching off or go into a high loss state.
As shown in
Illustratively, the HBT and field effect transistor (FET) devices are formed in a III-V semiconductor material such as Gallium Nitride, Indium Phosphide, or Gallium Arsenide/Indium Gallium Phosphide. In some applications, it may be advantageous to integrate the HBT and the FET device in a single semiconductor crystal by epitaxially growing the HBT device on an epitaxially grown FET device. Such a device and the process for making it in a GaAs/InGaP epitaxial growth process is described in U.S. Pat. No. 7,015,519, which is incorporated herein by reference. Other materials may also be used.
As will be apparent to those skilled in the art, numerous variations may be practiced within the spirit and scope of the present invention.
This application is a continuation of U.S. application Ser. No. 14/957,101, filed on Dec. 2, 2015 and titled “INTEGRATED RF LIMITER”, which is hereby incorporated by reference in its entirety herein and which claims benefit of provisional application Ser. No. 62/087,154, filed Dec. 3, 2014, which application is incorporated by reference herein in its entirety.
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| Number | Date | Country | |
|---|---|---|---|
| 20180019714 A1 | Jan 2018 | US |
| Number | Date | Country | |
|---|---|---|---|
| 62087154 | Dec 2014 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 14957101 | Dec 2015 | US |
| Child | 15663322 | US |
