Flat metamorphic InAlAs buffer layer on GaAs(111)A misoriented substrates by growth kinetics control

We have successfully grown, through the detailed control of the growth kinetics, flat InAlAs metamorphic buffer layers on 2 degrees -off GaAs(111)A substrates using molecular beam epitaxy. Almost full plastic relaxation is obtained for a layer thickness > 40 nm. The control of an adatom diffusion length and a step ejection probability from the bunches permits a reduction of the InAlAs epilayer root-mean-square surface roughness to 0.55 nm

Low-power BiCMOS continuous-time shaping filter

A biquadratic continuous-time filter designed to operate as signal shaper in the read-out electronics of elementary particles experiments has been implemented in 2 μm BiCMOS technology. The cell synthesizes a semi-Gaussian response with a shaping time adjustable in the range 18-30 ns. The power consumption is 1.25 mW from a single 5 V power supply. The integral nonlinearity is within 1% for an input signal amplitude up to 200 mV. The chip active area is 0.08 mm2. The measured input referred noise is 50 nV/√H

Baseband analog front-end and digital back-end for reconfigurable multi-standard terminals.

Multimedia applications are driving wireless network operators to add high-speed data services such as EDGE (E-GPRS), WCDMA (UMTS) and WLAN (IEEE 802.11a,b,g) to the existing network. This creates the need for multi-mode cellular handsets that support a wide range of communication standards, each with a different RF frequency, signal bandwidth, modulation scheme, etc. This in turn generates several design challenges for the analog and digital building blocks of the physical layer. In addition to the above mentioned protocols, mobile devices often include Bluetooth, GPS, FM-radio and TV services that can work concurrently with data and voice communication. Multi-mode, multi-band, and multi-standard mobile terminals must satisfy all these different requirements. Sharing and/or switching transceiver building blocks in these handsets is mandatory in order to extend battery life and/or to reduce cost. Only adaptive circuits that are able to reconfigure themselves within the handover time can meet the design requirements of a single receiver or transmitter covering all the different standards while ensuring seamless inter-operability. This paper presents analog and digital base-band circuits that are able to support GSM (with EDGE), WCDMA (UMTS), WLAN and Bluetooth using reconfigurable building blocks. The blocks can trade off power consumption for performance on the fly, depending on the standard to be supported and the required QoS (Quality of Service) level

A VDSL2 CPE AFE in 0.15µm CMOS with integrated line driver

VDSL2 transceivers use a wide analog bandwidth to achieve bit-rates in excess of 200 Mb/s. For standard 6-band VDSL2, 30 MHz bandwidth is required, comprising three up-stream and three down-stream signals. Since discrete multi tone (DMT) modulation is used, distortion components for the signal chain have to be below -65dBc to fully exploit 15b-per-tone bit loading. The presented AFE is implemented in a 0.15 mum triple-oxide CMOS process and uses three voltage supplies: 1.0 V for digital, 3.3 V for analog, and 7 V for the on-chip line driver (LD). All transceiver functionality is included in a single chip. The dynamic-range requirement of the receiver is achieved by the combination of a 2-stage 39 dB programmable-gain amplifier/anti-aliasing filter (PGA) followed by a 14b pipelined ADC, plus an analog echo canceller made of a 14b DAC followed by an adjustable-gain amplifier/filter