Twitter LinkedIn
Return to Wellspring


Stacked-transistor power amplifiers for high-power radio frequency and millimeter-wave wireless applications


Project TitleStacked-transistor power amplifiers for high-power radio frequency and millimeter-wave wireless applications
Track CodeP27954
Short DescriptionNone
Tagstransistor, cmos, class E power amplifier, power amplifier (PA), cascode, high frequency electronics, NMOS, soi,
Posted DateAug 17, 2017

IR #



This technology is an integrated circuit design for a stacked-transistor power amplifier (PA) that delivers the high output power required of wireless transmitters while maintaining ideal Class-E efficiency.

Unmet Need: Efficient high-power amplification for radio frequency and millimeter-wave transmitters

High-power amplification is a critical functionality for radio frequency (RF) and millimeter-wave transmitters. However, battery life is a key limitation in wireless systems such as cellular phones, Wi-Fi networks, and Bluetooth devices. Class-E switching PAs can achieve ideal 100%-efficient operation and are, therefore, highly useful in energy-sensitive applications. However, these amplifiers are typically limited in their output power capabilities due to the breakdown voltages associated with a given device technology. Cascaded designs can overcome this limitation and achieve high output powers, but existing stacked-transistor architectures do not realize the ideal Class-E behavior necessary for maximizing energy efficiency. As such, there is a need for a PA that can achieve high output powers with Class-E behavior for energy-efficient amplification.

The Technology: Stacked-transistor amplifier maintains Class-E switching, enabling high-efficiency power amplification

This technology is a stacked-transistor power amplifier that places a Class-E load network at the drain node of each stacked device to impart a true Class-E behavior to all devices in the stack. Unlike existing staked devices that are only partially successful in achieving Class-E behavior, this technology maintains Class-E-like behavior for all transistors in the stack. As a result, this technology enables high-power switching PAs for RF and millimeter-wave applications to be realized with standard CMOS processes, obviating the need for implementation of separate devices.

Two operational prototypes implemented in 45nm IBM Silicon-on-Insulator (SOI) technology have been successfully demonstrated at 45 GHz.

Lead Inventors:

Harish Krishnaswamy, Ph.D.

Patent Information:

Patent Pending (US 20170194920)

Patent Issued (US 9,431,975)

Potential Applications

  • Energy-constrained RF and millimeter-wave transmitters for wireless devices, including cellular phones, wireless LAN, millimeter-wave vehicular radar, and 60 GHz wireless personal area networks (WPANs)

  • High-efficiency, high-power PAs in CMOS technology enabling monolithic integration of the PA with the rest of the transmitter

  • Improved efficiencies and output power for III-V PAs

Tech Ventures Reference:


  • Achieves high output powers with ideal Class E behavior and efficiency

  • Enables high-efficiency, high-power PAs in both CMOS and III-V materials

  • Ideal class E behavior and efficiencies

  • Improved efficiencies and output power for III-V PAs



Greg Maskel
Columbia Technology Ventures
Tel: (212) 854-8444


Other Information

Principal Investigator