Mikko Kärkkäinen

94GHz power-combining power amplifier with +13dBm saturated output power in 65nm CMOS

A power combining power amplifier utilizing cascode topology and transformer-based matching elements is presented in this paper. The amplifier achieves +13 dBm saturated output power at 94 GHz with a standard 1.2 V supply and occupies an active area of only 0.069 mm2. Amplifier is implemented in an industrial 65nm CMOS process taking into account reliability issues at high output power level. The amplifier is also ESD-protected at the input and at the output.

Reflectarray for 120-GHz beam steering application: design, simulations, and measurements

Development of a 120-GHz FMCW radar with a reflectarray as focusing element is described. The reflectarray is realized on a 150-mm silicon wafer and it has 3700 phase-modulating elements on it. The phase shifters have four discrete values to cover full phase modulation with 90° steps. The reflectarray element is realized with a conductor-backed coplanar waveguide patch antenna with a phase shifter coupled to it. The required phase modulation for each reflectarray element is determined with an in-house physical optics simulation combined with genetic-algorithm-based optimization. The reflectarrays are developed in two stages. First, preliminary reflectarrays with static phase shifters have been manufactured and tested at 120-GHz antenna measurement range. The static reflectarrays are found to perform as designed in their capability to steer the beam to a desired direction and to a distance of 3 m. The reflectarrays have -3-dB beam width from 1.1° to 1.3° depending on the beam tilt. After the preliminary verification with the static phase shifters, the reflectarrays will be assembled together with actively controlled MEMS-based phase shifters. The MEMS switches are controlled with dedicated high-voltage CMOS electronics, forming a system-in-a-package (SiP). First, the MEMS phase shifters are modeled, are being fabricated, and will be measured separately to verify their phase-shifting capability.

MHEMT G-band low-noise amplifiers

To improve the performance of G-band equipment for humidity sounding of the atmosphere, a high-gain and low-noise amplifier is needed. Here, the performances of 165 and 183 GHz low-noise amplifier microchips intended for atmospheric water vapor profiling application are reported. The microchips are manufactured in metamorphic high-electron mobility transistor technology having a gate length of 50 nm. The on-wafer measured results show noise figures of 4.4-7.4 dB and 16-25 dB gain at the operating frequencies. In addition, two of the amplifiers were assembled in waveguide packages and the measured results show a gain of 19-20 dB and 7 dB noise figure at both 165 and 183 GHz.

A 97–106-GHz differential I-Q phase shifter in 28-nm CMOS

This paper presents the design and corresponding measurement results of a W-Band differential I-Q phase shifter in 28-nm CMOS technology. Design of CMOS active switches and passive components like a 90° hybrid realized for differential I-Q operation are shown. The phase of the RF signal can be varied from 0° to 270° in steps of 90°. The measured input and output matching are better than -10 dB, and the maximum output imbalance is 0.8 dB with a maximum phase error of 19.6° at 100 GHz. Using a 1-V supply voltage, the total power consumption is 39 mW. The die area is 0.458 mm2.

Design of a W-Band 2-bit differential CMOS phase shifter

This paper presents the design of a W-Band I-Q phase shifter and the corresponding simulation results in 28-nm CMOS technology. The design of passive components like a 90° hybrid and transformers needed to realize differential I-Q operation is shown. The phase of the RF signal can be varied from 0° to 270° in steps of 90°. The simulated input and output matching are better than -10 dB, and the maximum phase error is roughly 10° with a maximum output imbalance of 0.5 dB at 90 GHz using a 1-V supply voltage. The total power consumption is 41 mW and the die area is 0.46 mm2.

Design of mixers for a 130-GHz transceiver in 28-nm CMOS

A compact and 3-dB bandwidth of 118-145-GHz Gilbert-cell mixer for up-conversion and a 1-dB bandwidth of 106-143-GHz image-rejection (IR) resistive mixer for down-conversion are designed for a 130-GHz transceiver in 28-nm CMOS technology. A wide 10-GHz intermediate frequency (IF) tuning range is obtained for both mixers. The simulated results show a +1.6-dB conversion gain for the Gilbert-cell mixer with a layout size of 720×633 μm2 and 6.1 mW of DC power consumption. An 11-dB conversion loss and 30-dB IR ratio are simulated for the resistive mixer with a layout size of 845×794 μm2. The simulated 1-dB output compression point is -8 dBm for the Gilbert-cell mixer and 1-dB input compression point is +9 dBm for the resistive mixer.

The Combined Effects of Sr Additions and Heat Treatment on the Microstructure and Mechanical Properties of High Pressure Die Cast A383 Alloy

The combined effects of heat treatment and strontium (Sr) additions on the microstructure and mechanical properties of high pressure die cast A383 alloy components were investigated. A series of high pressure die cast engine components were produced using combined Sr additions and heat treatments. The resulting micro- and nanostructures were characterized using optical and electron microscopies. The tensile behavior was measured for material taken from the bulkhead sections of the engine bock. The results showed that Sr additions increased the elongation, but not the strength, of as-cast A383 alloys due to the refinement of the Al–Si eutectic. Heat treatment combined with Sr addition improved the strength because of the formation of fine nano-precipitates with a high number density. The results suggest that the formation of these precipitates may be affected by the Sr additions. This same combination also improved the ductility by maintaining the small size and roundness of the Al–Si eutectic particles.

A Modeling and Experimental Investigation on the Formation of Acicular Silicon and Sludge in High Pressure Die Casting of a Modified A383 Alloy

A numerical model is being developed to predict the formation of sludge (e.g., Fe-containing intermetallic compounds) and acicular silicon during high pressure die casting (HPDC) of a modified aluminium A383 alloy. The iron-rich sludge-phase and silicon rich phases with needle-like morphology play a major detrimental role in the mechanical properties, especially the fracture characteristics, of high pressure die cast engine components. The modelling approach consists of using a macroscopic fluid flow, heat transfer and solidification model to predict the cooling rates in the HPDC A383 process. The results are being compared against experimental measurements (e.g., amount, type and size of detrimental phases) in A383 samples extracted from various regions of an HPDC engine block. The approach can be applied to predict the effects of cooling rate on the final phase microstructure.