Broadband, Linear, and High-Efficiency Mm-Wave PAs in Silicon ― Overcoming Device Limitations by Architecture/Circuit Innovations

Mm-Wave 5G links and many emerging mission-critical DoD applications have recently stimulated major research efforts on next-generation mm-Wave power amplifiers (PAs) to deliver nearly "perfect" large-signal performance. Compared to compound semiconductors, silicon often exhibits inferior device-level capabilities on power density, gain, efficiency, linearity, and reliability. On the other hand, silicon technologies offer matured modeling, flexible back-end options, and extensive digital controls, making them a highly versatile and attractive platform for design innovations and system integrations. This paper reviews several recent silicon mm-Wave PAs from multiple research groups, which all leverage architecture/circuit innovations to overcome device limitations and radically advance the state of the art. These design explorations include Doherty/Outphasing active load modulation, continuous-mode operation, broadband harmonic tuning, nonlinearity cancellation, and power-DACs.