Maki Nakamura

A 60GHz wireless transceiver employing hybrid analog/digital beamforming with interference suppression for multiuser gigabit/s radio access

This paper presents a 60GHz analog/digital beamforming transceiver that effectively suppresses interference signals, targeting WiGig/IEEE 802.11ad standard. A prototype has been built with 40nm CMOS analog front-ends as well as offline baseband digital signal processing. Measurement shows 3.1dB EVM advantage over the conventional two-stream diversity during a packet collision situation.

ISO-less, SAW-less open-loop polar modulation transceiver for 3G/GSM/EDGE multi-mode/multi-band handset

In this paper, a new 3G/GSM/EDGE multi-mode/multi-band transceiver that achieves both the elimination of TX-SAW filter and the isolator using an open-loop polar modulation transmitter is presented. Sufficient ACLR performance is accomplished by a combination of parts-to-parts calibration and temperature offset compensation. ACLR meets 3GPP target specification at VSWR=3∶1, with Rx band noise at PA output in UMTS band I of −132.3dBm/Hz thus does not degrade receiver sensitivity. This paper includes design details and experimental results.

Accurate UMTS power transition with power alignment loop between two different modulation modes for polar transmitters

Generally low power region is very dominant for current consumption on UMTS handsets. However, a polar modulation architecture has a little bit lager current consumption in this region. So, we propose polar/quadrature modulation architecture with a fast-feedback power control technique “power alignment loop (PAL)”. The PAL can realize accurate UMTS power transition over the two different modulation modes. Measurement results shows that the power accuracy between the two modes can satisfy the 3GPP standard within 25 µs from the slot boundary. The average current consumption of the transmitter is 128 mA at the battery.