Efficient, high-power millimeter-wave (mmwave) digital-polar phased array transmitter in CMOS for long-range, high-speed, low-cost wireless telecommunications

Efficient, high-power transmitters capable of supporting complex modulation formats are integral for high-speed data transmission over long distances, particularly in the mmwave regime. However, conventional transmitters typically face a trade-off between output power and average efficiency. This technology proposes a "digital" mmwave transmitter based on a digital-polar phased array power amplifier (PA) that simultaneously achieves high output power as well as high peak and average efficiencies. With this technology, unprecedented performance improvement can be achieved for long range high-data-rate communications in the mmwave regime using a low-cost fully integrated, silicon platform with a compact footprint.

"Digital" power amplifier (PA) for direct digital-to-millimeter-wave converters (DACs) using stacked PAs with switched-capacitor supply modulation and supply-adaptive biasing facilitates high-power operation with high average efficiency

Power amplifiers are typically most efficient at their saturation point. Direct digital-to-mmwave converters (DACs) using stacked PAs with high peak efficiency have recently been proposed as a feasible means of implementing mmwave transmitters capable of supporting complex modulations for high data-rate communications. This technology augments the stacked PAs in the mmwave DAC with switched-capacitor supply modulation to facilitate high average efficiency as well. Additionally, the stacked PAs utilize a novel supply-adaptive biasing scheme to retain stacked-PA characteristics under supply modulation. This furthers aids operation with high average efficiency. A high-speed deserializing receiver is integrated with the transmitter to facilitate high-speed operation of digital control bits. These features uniquely enable this technology to function as a mmwave power DAC-based transmitter capable of supporting high-speed complex modulations with high average efficiency.

A prototype demonstrating the feasibility of stacked mmwave power DACs for supporting modulated data with high average efficiency has been tested.

Lab Director:

Harish Krishnaswamy, Ph.D.

Applications:

• Transmitters for broadband telecommunications
• Transmitters for high-speed long-distance wireless links
• Transmitters for millimeter-wave broadband wireless and telecommunications backhaul

Advantages:

• High peak output power, facilitating long-distance communication with low gain integrated (on-chip or on PCB) antennas
• Phased array operation for electronic steerability, mitigating precise mechanical alignment requirements as in high gain antennas
• High peak and average efficiencies, translating to longer battery life
• "Digital" transmitter architecture, making it CMOS technology scaling friendly
• Integrated deserializing receiver facilitates high-speed operation of digital control bits, translating to high data-rates
• System-on-chip (SoC) solution in a low-cost, fully integrated silicon platform

Patent Information:

Patent Issued

Tech Ventures Reference: IR CU14221

Related Publications:

• Krishnaswamy H., Chakrabarti A., Bhat R., "The path to efficient-yet-linear watt-class mmWave CMOS PAs: device stacking, switch-mode operation, power combining and linearization." 2014 Power Amplifier Symposium.