At IMS 2016 in San Francisco, Peregrine Semiconductor demonstrated their monolithic phase and amplitude controller (MPAC) - Doherty with an RFHIC gallium nitride (GaN) Doherty amplifier. The MPAC–Doherty PE46140 was used with two RFHIC GaN devices—the IE36170WD and the IEQ3656D—in a Doherty power amplifier (PA) configuration. The demo showed how quickly and reliably the MPAC - Doherty controller was able to compensate for Doherty device and manufacturing variations at 3.5 GHz.
Peregrine's MPAC - Doherty products provide automated optimization of transceivers that improves Doherty PA yield and performance. These products will play a critical role in the proliferation of GaN by eliminating the need for cumbersome and intensive manual tuning.
While widely used in the wireless infrastructure industry, Doherty amplifiers require a considerable engineering investment to manually implement and optimize. Any mismatch or misalignment in phase and amplitude between the Doherty architecture’s carrier and peaking paths can quickly contribute to higher costs and degradation of the system’s overall performance. Even after optimizing with discrete components, the system remains inflexible to manufacturing variances from power amplifier assemblies. The MPAC–Doherty products eliminate the need for discrete components and enable phase and amplitude control through a digital interface.
With a frequency range extending from 3.4 to 3.8 GHz, the UltraCMOS PE46140 is ideal for optimizing GaN-based Doherty PAs. This controller integrates a 90-degree RF splitter, digital phase shifters, a digital step attenuator and a digital serial peripheral interface (SPI) on a single monolithic die. It reduces the bill of materials (BoM) by improving the overall yield of expensive Doherty power amplifier assemblies utilizing high efficiency GaN transistors. Additionally, this controller offers performance advantages in power added efficiency, linearity across the frequency range, Doherty bandwidth through better matching and increased effectiveness of the digital pre-distortion (DPD) loop. The maximum tuning flexibility enables uniformity and repeatability between transceiver paths, while increasing system reliability. This monolithic controller can be programmed remotely through the digital interface to accommodate varying field requirements. This flexibility allows engineers to adjust the phase and amplitude in real-time for operational and environmental factors.
The RFHIC IEQ3656D and the IE36170WD are symmetrical Doherty GaN high-electron-mobility transistor (HEMT) devices. The IEQ3656D has an operating frequency of 3.4 to 3.8 GHz, while the IE36170WD supports a frequency range from 3.52 to 3.56 GHz. Offered in a DFN package, the IEQ3656D delivers saturated output power (PSAT) of 56W at 48V operation. The IE36170WD provides PSAT of 170W at 48V operation.
