Accurate prediction of PHEMT intermodulation distortion using the nonlinear discrete convolution model

A general-purpose, technology-independent behavioral model is adopted for the intermodulation performance prediction of PHEMT devices. The model can be easily identified since its nonlinear functions are directly related to conventional DC and small-signal differential parameter measurements. Experimental results which confirm the model accuracy at high operating frequencies are provided in the pape

Impact of liver tumour burden, alkaline phosphatase elevation, and target lesion size on treatment outcomes with 177Lu-Dotatate: an analysis of the NETTER-1 study

Purpose: To assess the impact of baseline liver tumour burden, alkaline phosphatase (ALP) elevation, and target lesion size on treatment outcomes with 177Lu-Dotatate. Methods: In the phase 3 NETTER-1 trial, patients with advanced, progressive midgut neuroendocrine tumours (NET) were randomised to 177Lu-Dotatate (every 8 weeks, four cycles) plus octreotide long-acting release (LAR) or to octreotide LAR 60 mg. Primary endpoint was progression-free survival (PFS). Analyses of PFS by baseline factors, including liver tumour burden, ALP elevation, and target lesion size, were performed using Kaplan-Meier estimates; hazard ratios (HRs) with corresponding 95% CIs were estimated using Cox regression. Results: Significantly prolonged median PFS occurred with 177Lu-Dotatate versus octreotide LAR 60 mg in patients with low ( 50%) liver tumour burden (HR 0.187, 0.216, 0.145), and normal or elevated ALP (HR 0.153, 0.177), and in the presence or absence of a large target lesion (diameter > 30 mm; HR, 0.213, 0.063). Within the 177Lu-Dotatate arm, no significant difference in PFS was observed amongst patients with low/moderate/high liver tumour burden (P = 0.7225) or with normal/elevated baseline ALP (P = 0.3532), but absence of a large target lesion was associated with improved PFS (P = 0.0222). Grade 3 and 4 liver function abnormalities were rare and did not appear to be associated with high baseline liver tumour burden. Conclusions: 177Lu-Dotatate demonstrated significant prolongation in PFS versus high-dose octreotide LAR in patients with advanced, progressive midgut NET, regardless of baseline liver tumour burden, elevated ALP, or the presence of a large target lesion. Clinicaltrials.gov: NCT01578239, EudraCT: 2011-005049-11

Risk profiles and one-year outcomes of patients with newly diagnosed atrial fibrillation in India: Insights from the GARFIELD-AF Registry.

BACKGROUND: The Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF) is an ongoing prospective noninterventional registry, which is providing important information on the baseline characteristics, treatment patterns, and 1-year outcomes in patients with newly diagnosed non-valvular atrial fibrillation (NVAF). This report describes data from Indian patients recruited in this registry. METHODS AND RESULTS: A total of 52,014 patients with newly diagnosed AF were enrolled globally; of these, 1388 patients were recruited from 26 sites within India (2012-2016). In India, the mean age was 65.8 years at diagnosis of NVAF. Hypertension was the most prevalent risk factor for AF, present in 68.5% of patients from India and in 76.3% of patients globally (P < 0.001). Diabetes and coronary artery disease (CAD) were prevalent in 36.2% and 28.1% of patients as compared with global prevalence of 22.2% and 21.6%, respectively (P < 0.001 for both). Antiplatelet therapy was the most common antithrombotic treatment in India. With increasing stroke risk, however, patients were more likely to receive oral anticoagulant therapy [mainly vitamin K antagonist (VKA)], but average international normalized ratio (INR) was lower among Indian patients [median INR value 1.6 (interquartile range {IQR}: 1.3-2.3) versus 2.3 (IQR 1.8-2.8) (P < 0.001)]. Compared with other countries, patients from India had markedly higher rates of all-cause mortality [7.68 per 100 person-years (95% confidence interval 6.32-9.35) vs 4.34 (4.16-4.53), P < 0.0001], while rates of stroke/systemic embolism and major bleeding were lower after 1 year of follow-up. CONCLUSION: Compared to previously published registries from India, the GARFIELD-AF registry describes clinical profiles and outcomes in Indian patients with AF of a different etiology. The registry data show that compared to the rest of the world, Indian AF patients are younger in age and have more diabetes and CAD. Patients with a higher stroke risk are more likely to receive anticoagulation therapy with VKA but are underdosed compared with the global average in the GARFIELD-AF. CLINICAL TRIAL REGISTRATION-URL: http://www.clinicaltrials.gov. Unique identifier: NCT01090362

Statistical modelling of electron devices based on an equivalent-voltage approach

Active device modelling and statistical description of the device behaviour are two key aspects in the design of high-yield integrated circuits.A new empirical approach is here proposed which is capable of describing the effects of process parameter variations on the electron device electrical response by means of only a few statistical parameters.The model can be easily identified on the basis of conventional electrical measurements.Preliminary validation results from experimental data,simulations using the Trew analytical model and simulations of a modified Curtice model are provided in the paper

12-W X-Band MMIC HPA and Driver Amplifiers in InGaP-GaAs HBT Technology for Space SAR T/R Modules

The chip-set for the transmitting power lineup of satellite SAR antenna T/R modules has been designed and implemented exploiting a 2- &#956;m GaInP-GaAs heterojunction bipolar transistor (HBT) technology suitable for space applications. The HBT technology features an integrated emitter ballast resistor that enables high-power density operation without suffering thermal runaway phenomena. Two monolithic microwave integrated circuit (MMIC) driver amplifiers and a MMIC HPA are described: the drivers exhibit small-signal gains exceeding 21 dB and P1 dB output power of about 28 and 29 dBm, respectively, in a 2-GHz bandwidth and CW condition. The HPA delivers more than 40-dBm power at about 2.5-dB gain compression and power-added efficiency (PAE) exceeding 36% in a 700-MHz bandwidth in pulsed operation. Its peak performance at the center of the band are 40.9-dBm output power and 45% PAE. These performance are obtained within tight de-rating conditions for space applications

Equivalent-voltage description of dispersive effects for accurate large-signal transistor modeling

Equivalent-voltage description of dispersive effects for accurate large-signal transistor modelin

Design of L and X band class E power amplifiers with GaAs pHEMT technology for space SAR

The paper describes the design of class E power amplifiers for SAR space applications, exploiting a 0.35-um pHEMT GaAs process. An L-band 10-Watt push-pull hybrid amplifier has been designed and implemented. The HPA features 73% PAE and 81% drain efficiency at 1.275 GHz. The performances of the class E HPA are also compared with a class AB HPA, exploiting the same technology. Class E design was also evaluated at X band, which for this technology is beyond the limit for the devices' class E operation capability. Two different prototype amplifiers were designed exploiting different device periphery. The single-cell amplifier delivers about 31 dBm output power with 64% peak PAE, whereas the double-cell circuit features 27 dBm output power with 70% peak PAE. These prototype amplifiers prove the possibility to use this process for the design of X band MMIC HPA for SAR space applications operating with high efficiency

Equivalent-Voltage Approach for Modeling Low-Frequency Dispersive Effects in Microwave FETs

In this paper, a simple and efficient approach for the modeling of low-frequency dispersive phenomena in FETs is proposed. The method is based on the definition of a virtual, nondispersive associated device controlled by equivalent port voltages and it is justified on the basis of a physically-consistent, charge-controlled description of the device. Dispersive effects in FETs are accounted for by means of an intuitive circuit solution in the framework of any existing nonlinear dynamic model. The new equivalent-voltage model is identified on the basis of conventional measurements carried out under static and small signal dynamic operating conditions. Nonlinear experimental tests confirm the validity of the proposed approach

Efficient X-band transmitter with integrated GaN power amplifier and supply modulator

In this paper, we present a high-efficiency transmitter based on an integrated circuit (IC) supply modulator implemented in the same 0.15\u3bcm gallium nitride (GaN)-on-SiC RF process as the power amplifier (PA) monolithic microwave IC. The X-band 10-W two-stage PA is designed for stable operation with minimal drain capacitance, which enables fast supply modulation. The multilevel supply modulator provides eight voltage levels with 3-bit digital control [(power digital-to-analog converter (pDAC)], achieving a state-of-the-art slew rate of 5 kV/\u3bcs. Characterization of the dynamic R ON of the GaN switches allows the development of an efficiency model for the pDAC and an investigation of the effects of the pDAC internal resistance on the PA performance, resulting in a comprehensive efficiency model for the supply-modulated PA. The flexible compact transmitter consisting of the PA and pDAC ICs shows high efficiency in backoff for a variety of signals, both for radar and communications. Measured results for amplitude- A nd frequency-modulated radar pulses show a composite power-added efficiency (CPAE) of 44% with a peak power of 10 W at 9.57 GHz, with simultaneous spectral confinement and 52-dB improvement of the first time sidelobe. For a 20-MHz high peak-to-average ratio LTE signal, the CPAE increases from 11% to 32% compared to a fixed supply voltage transmitter, while linearity under dynamic supply operation is maintained through digital predistortion

A 48Watt and 60dB Gain Hybrid Power Line-Up for an L-Band T/R Module of a Space SAR Antenna

This paper describes the design, implementation and characterization of an entire transmitting line-up of an L-band T/R module for space application. The module is used in the array of a SAR antenna for earth observation. The entire line-up described in this paper is composed of three stages, namely pre-driver, driver and final-stage HPA, for an overall small-signal gain of 60 dB at 1275 MHz central frequency. The application bandwidth is 80 MHz and the output power of the module exceeds 48 Watts over the bandwidth under pulsed operating conditions (60 &#956;s pulse width at 10% duty cycle). The PAE of the entire line-up is over 43% across the bandwidth. A 0.35-&#956;m gate length GaAs pHEMT process has been used for the design of the three stages: the pre-driver is a 2-stage monolithic circuit with external drain bias chokes, while both the driver and the final HPA are hybrid circuits, which exploit a 15-mm gate width power bar designed with internal stabilization and pre-matching distributed structures. Microstrip structures on alumina, gold bonding wires and custom-designed ceramic MIM capacitors have been used for lumped and distributed matching and combining networks. Gold wire coils are exploited as bias chokes. The entire line-up is very compact for L-band: with all bias networks and stabilizing capacitors included, it takes up a space of 36x30 mm within the T/R module