Steven M. Bowers

Integrated Self-Healing for mm-Wave Power Amplifiers

Self-healing as a technique for improving performance and yield of millimeter-wave power amplifiers (PAs) against process variation and transistor mismatch, load impedance mismatch, and partial and total transistor failure is described and investigated. A 28-GHz PA is presented with three types of sensors, two types of actuators, data converters, and a digital algorithm block that are all integrated on a single chip to show the validity of the technique. Two algorithms are implemented to either maximize output power or to minimize dc power for a desired output power. Measurements from 20 chips show increased RF output power up to 3 dB or reduced dc power by 50% in backoff with a 50-Ω load. Self-healing with up to 4-1 voltage standing-wave ratio load impedance mismatch is verified and linear operation under nonconstant envelope modulation is shown to improve with healing. Self-healing after laser cutter induced transistor failure is verified and increases RF output power by up to 5.4 dB. The aggregate yield of the PA across several representative specifications is increased from 0% to 80% with self-healing.

Multi-Port Driven Radiators

Integrated multi-port driven (MPD) radiator design is presented as an approach that takes advantage of the increased design space offered by using a hybrid design of an antenna with multiple ports and its driver circuitry integrated together on a single substrate. This reduces costly losses by eliminating independent elements for power combination, output impedance matching networks, and power transfer by engineering current patterns on a chip based on the desired far field pattern. The electromagnetic radiation produced by a circularly polarized MPD antenna is calculated analytically to provide design intuition, with supporting electromagnetic simulations. A single element 160 GHz MPD antenna and the supporting driver circuitry is designed and fabricated in a 0.13 μm SiGe BiCMOS process. A tuned 8 phase ring oscillator generates the signal with each phase feeding class A power amplifiers that drive the antenna. The radiator achieves 4.6 dBm single element effective isotropically radiated power (EIRP) and total radiated power of -2.0 dBm at 161 GHz while consuming 117.5 mA DC current from a 3.3 V source. Measurements of three frequency bands at 145, 154 and 161 GHz show greater than 0 dBm EIRP for each band, demonstrating the wide band nature of the antenna.

A fully-integrated self-healing power amplifier

A fully-integrated self-healing mm-wave power amplifier heals process variation, load mismatch, and transistor failure with on-chip sensors, actuators and an integrated digital algorithm ASIC without external calibration. Measurements of 20 chips showed increased RF power up to 3dB, or reduced DC power by 50% in backoff at 28 GHz. Healing 4-1 VSWR load mismatch for RF and DC power improvement was verified, and healing after laser induced transistor failure increased RF power up to 4.8dB.

On-chip sensing and actuation methods for integrated self-healing mm-wave CMOS power amplifier

This paper presents various low power, compact, low insertion-loss sensors with digitized ADC output and digitally controlled actuation methods for on-chip characterization and healing of a mm-Wave power amplifier. We demonstrate low insertion loss (0.4dB) RF sensors which measure true input and output power in presence of load variations and very low-headroom (10–30mV) DC sensors with built-in regulators and thermal sensors as methods for measuring PA efficiency. All sensor outputs are digitized by a SAR-based ADC for communication with a central digital core. The paper also presents digitally controlled combiner tuning and PA bias actuation. The circuits are implemented in 45 nm SOI CMOS and enable full on-chip digitally controlled characterization and actuation of the PA with a power overhead of less than 6%.

Dynamic Polarization Control of Two-Dimensional Integrated Phased Arrays

Simultaneous two-dimensional (2-D) beam steering and dynamic polarization control (DPC) of the radiated electric field in 2-D phased arrays ensure polarization matching between the transmitter and receiver antennas in both fixed and mobile wireless systems. Polarization matching is maintained regardless of the polarization, orientation, and location of the receiver antenna in space within the 2-D steering range of the transmitter. This work implements a fully integrated 2 × 2 DPC phased-array transmitter in a 32-nm CMOS silicon-on-insulator process, radiating at 122.9 GHz. It achieves a maximum effective isotropic radiated power of +12.3 dBm in the broadside direction and enables polarization angle control of the radiated linear and elliptical polarizations across the full range of 0 ° to 180 ° with tunable axial ratio down to 1.2 dB to achieve circular polarization and the ability to steer the radiated beam up to 15 ° in both dimensions.

An Integrated Slot-Ring Traveling-Wave Radiator

Electromagnetic duality is used to design a multi-port traveling-wave slot-ring antenna with on-chip driver circuitry to create a fully integrated radiator. By creating a slot version of the multi-port driven antenna, the required exclusive use area of the antenna is significantly decreased, while still being able to perform impedance matching, power combining, and power transfer off chip through electromagnetic radiation in a single step. The driver core consists of an oscillator followed by three amplification stages. A split path inductor design was utilized to reduce the radiators dependence on process variation in the metal stack while ensuring proper isolation between the four quadrature paths. The slot radiator has a simulated antenna efficiency of 39% and a measured single-element effective isotropic radiated power of 6.0 dBm with a total radiated power of -1.3 dBm at 134.5 GHz.

Dynamic Polarization Control of integrated radiators

Dynamic Polarization Control (DPC) ensures polarization matching to the receiving antenna regardless of its polarization or orientation in space. A fully integrated 105.5 GHz 2×1 DPC multi-port driven radiator array with beam steering radiates linear polarization across the full polarization angle range of 0° to 180° maintaining axial ratios above 10 dB, and controls the axial ratio from 2.4 dB (near circular) to 13 dB (linear) in various directions of radiation and a maximum EIRP of 7.8 dBm.

An integrated traveling-wave slot radiator

A traveling-wave integrated slot radiator is designed using electromagnetic duality theory based off of the ring portion of a radial multi-port driven radiator to minimize the area required exclusively for the antenna. It is designed in 32 nm SOI CMOS and driven by a buffered quadrature VCO at 4 points to create the traveling wave that radiates out of the backside of the chip. It is measured to have a maximum EIRP of 6.0 dBm at 134.5 GHz with a total radiated power of -1.7 dBm while drawing 168 mW DC power.

An integrated multi-port driven radiating source

A multi-port driven (MPD) antenna allows for the removal of RF blocks for impedance matching, power combining, and power delivery by enabling efficient radiation at the fundamental frequency from several output stages driving the antenna. A radiating source utilizing an 8-phase ring oscillator and eight power amplifiers to drive the MPD antenna at 161.4 GHz with a total radiated power of -2 dBm and a single element EIRP of 4.6 dBm is demonstrated in silicon with single lobe radiation patterns closely matching simulation.

Analysis of quadratic dickson based envelope detectors for IoE sensor node applications

This paper presents a study of passive Dickson based envelope detectors operating in the quadratic small signal regime, specifically intended to be used in RF front end of sensing units of IoE sensor nodes. Critical parameters such as open-circuit voltage sensitivity (OCVS), charge time, input impedance, and output noise are studied and simplified circuit models are proposed to predict the behavior of the detector, resulting in practical design intuitions. There is strong agreement between model predictions, simulation results and measurements of 15 representative test structures that were fabricated in a 130 nm RF CMOS process.