RF Frontend Solutions for 5G and Beyond

Load-Modulated Balanced Amplifier

with Extended Power Back-off Range


Balanced-to-Doherty Mode-Reconfigurable PA for Massive MIMO and Active Array Applications


The wireless communications of 5G and beyond facilitate unprecedented quality of service, such as ultrahigh speed and low latency. However, this evolution inevitably brings about severe energy inefficiency mainly due to the degraded efficiency of RF power amplifiers (PAs) that are the most power-consuming unit in wireless systems. As a pioneer in this field, INSPIRE lab is committed to explore innovational solutions of power amplifier and radio frontend to break the current technological barriers.

By combining the new load-modulated balanced amplifier with Doherty-like bias setting and dynamic phase tuning, we for the first time demonstrated the PA efficiency enhancement up to 10-dB power back-off, leading to highly efficient amplification of 5G signals with high peak-to-average-ratio (PAR). Meanwhile, we have discovered a new Doherty PA architecture based on the standard balanced amplifiers, which enables reconfiguration between Doherty mode and balanced mode. This new type of mode-reconfigurable PA offers an effective solution to the antenna impedance mismatch issues in 5G systems due to the massive MIMO and beamforming operations.

Ultra-Wideband High-Performance Power Amplifiers


The First-Ever Dynamic-Load-Modulation PA with High Linearity and Efficiency over Octave-Bandwidth

Frequency-band proliferation has become a signature of modern wireless communications due to the insatiable need for spectrum resources. To cover such a rapidly growing number of fragmented spectra, RF power amplifiers are generally demanded to operate linearly and efficiently over an extensive frequency span. Having made significant contributions in this emerging field, e.g., first-ever discoveries of “mode-transferring” technique, multi-stage lowpass matching network synthesis & realization, and wideband dynamic load modulation. INSPIRE lab will continue to explore innovational wideband PA theories and techniques towards future-generation multi-band multi-mode communications as a key enabler to intelligent software-defined radios.

Co-Design of Circuits and Electromagnetics

Co-Design of PA & Filter


The electronic circuits (e.g., amplifiers) and electromagnetic structures (e.g., filters, antennas) are both essential modules in a radio system. Conventionally, they are designed independently and inter-connected through a universal 50-ohm interface. This, however, does not lead to the maximized system performance since no global optimization is achieved. Co-design of critical modules across circuit domain and EM domain along the radio transceiver chain can well solve this issue. Based on the unique synthesis method, the INSPIRE lab has demonstrated the first-ever co-designed power amplifier and frontend filter with direct connection and matching of filter and transistor. With the elimination of PA matching network, a significantly enhanced efficiency has been experimentally demonstrated. Looking into the future generation radio systems, co-design of the entire transceiver chain from IC to antenna will play an important role in achieving the globally optimized system performance.

Advanced Carrier-Aggregation Architectures


As an emerging technology first introduced in the LTE-Advanced standard, carrier aggregation (CA) can effectively increase the total available bandwidth for a mobile user by aggregating multiple scattered spectral recourses. Widely deployed in wireless systems, CA technology leads to multiplied channel capacity at user level, as well as enhanced spectrum utilization efficiency and resource allocation flexibility at the system/network level. We have successfully demonstrated multiple innovational CA architectures winning the 1st place in IEEE MTT-S Student Design Competition (2018 and 2019). As a key enabler for vast enhancement of channel-capacity, ground-breaking CA architectures will be further explored towards 100Gbps data rate as well as ultimate spectrum-utilization efficiency and access flexibility.