QFN-packaged highly-linear cascode GaN LNA MMIC from 0.5 to 3 GHz

A GaN high electron mobility transistor technology with a gate length of 0.25 μm has been used to design and fabricate a cascode broadband low noise amplifier (LNA). The two-stage monolithic microwave integrated circuit (MMIC) with feedback topology yields a bandwidth of 0.5-3 GHz at a constant gain of 35 dB and noise figures of less than 1.5 dB. A third order intercept point (OIP3) of up to 42.5 dBm was measured at 0.8 GHz, with a linear output power of 24 dBm over the full bandwidth. The MMIC was further assembled and measured in a low-cost plastic QFN package on an evaluation board with optimized thermal design and passive cooling. At a power dissipation of ~3 W the packaged LNA yields an OIP3 of 35-38 dBm over the full bandwidth at a noise figure of <; 1.9 dB

Noise analysis in distributed amplifiers with feedback-active load

This paper presents the noise analysis of amplifiers when the input line termination is implemented via an active load. The noise figure (NF) of distributed amplifiers is analysed to determine the effect of the gate and drain terminations. The noise of a transistor configured as a one-port device has been analysed and a lower noise temperature has been achieved as compared with a conventional resistor. In order to improve the noise performance of the overall amplifier, a parallel feedback has been added to the active load, and its effects are analysed in terms of noise. A distributed amplifier has been designed as a test vehicle of the analysis and characterised with a resistor as input line termination and with an active load to demonstrate the improvement in NF at frequencies below 2 GHz. The resulting amplifier exhibits 10.9 dB of small signal gain from 1 to 5 GHz, with a reduction of 0.6 dB in NF below 2 GHz when the input line termination is replaced by an active load.This work was supported by the Ministerio de Economía y Competitividad from Spain under the CONSOLIDER-INGENIO 2010 program CSD2010-00064 reference, and the research program FPI BES-2011-046199

Cryogenic performance of a 3-14 GHz bipolar SiGe low-noise amplifier

The performance of silicon-germanium (SiGe) transistors under cryogenic operation is analysed. The design and characterization of a 3–14 GHz low-noise amplifier (LNA) using SiGe transistors at 300 K and at 13 K are presented. A three stage amplifier is implemented with bipolar transistors model BFU910F from NXP commercially available with a plastic package. The amplifier exhibits 36.8 dB average gain with average noise temperature of 103 K and 42 mW DC power consumption at 300 K ambient temperature. Whereas cooled down to 13 K ambient temperature, it provides 32.4 dB average gain, 11.4 K average noise temperature with a minimum of 7.2 K at 3.5 GHz and a DC power dissipation of 5.8 mW. The presented LNA demonstrates an outstanding performance at cryogenic temperature for a commercial plastic packaged transistor.The authors would like to thank the Spanish Ministry of Economy, Industry and Competitiveness for the financial support provided under the grant ESP2015-70646-C2-2-R

Double square waveguide directional coupler for polarimeter calibration

A novel full-band square waveguide coupler design based on directional couplers which couple the TE10 and TE01 orthogonal modes in a square waveguide is presented. This waveguide coupler is aimed at the calibration of polarization receivers. This is composed of a pair of rectangular waveguide directional couplers, which are rotated 90° between them and both are coupled to the main square waveguide through each one of the square section walls. The coupler covers the full frequency band from 10 to 18.9 GHz. It has inherent low cross-polarization, which allows obtaining any known elliptically polarized wave at a square waveguide when a signal is applied to the couplers. The fabricated prototype of this coupler exhibits 31 dB of coupling, with flatness of ±3.8 dB and excellent cross polarization better than 50 dB over the whole band.This work was supported by the Spanish Ministry of Economy and Competitiveness under Grant ESP2015-70646-C2-2-R

Calibration of a polarimetric microwave radiometer using a double directional coupler

This paper presents a built-in calibration procedure of a 10-to-20 GHz polarimeter aimed at measuring the I, Q, U Stokes parameters of cosmic microwave background (CMB) radiation. A full-band square waveguide double directional coupler, mounted in the antenna-feed system, is used to inject differently polarized reference waves. A brief description of the polarimetric microwave radiometer and the system calibration injector is also reported. A fully polarimetric calibration is also possible using the designed double directional coupler, although the presented calibration method in this paper is proposed to obtain three of the four Stokes parameters with the introduced microwave receiver, since V parameter is expected to be zero for the CMB radiation. Experimental results are presented for linearly polarized input waves in order to validate the built-in calibration system.The authors would like to thank The Spanish Ministry of Science and Innovation for financial support provided through the grants ESP2015-70646-C2-2-R, ESP2017-83921-C2-2-R and PID2019-110610RB-C2

Cryogenic broadband Q-band MMIC low-noise amplifier

The design of a broad-band monolithic cryogenic low-noise amplifier (MMIC LNA) in the Q band, aimed to be used in radio-astronomy receiver front-end modules is presented. A 70 nm gate-length GaAs mHEMT process from OMMIC foundry is used to manufacture the amplifier. An accurate model for the minimum noise bias point of the transistor has been obtained at room temperature. The amplifier design is based on a four stage monolithic common source transistor configuration. At 300 K, the amplifier shows an associated gain of 28 ± 1.1 dB and an average noise temperature of 145 K with a minimum noise temperature of 101 K at 45 GHz tested on wafer. When cooled down at 15 K, the average noise temperature is 18.4 K with a minimum of 13.5 K and 27.3 dB of associated gain. The DC power consumption is extremely low, 4.1 mW, at cryogenic temperatureThis work was supported by the Ministerio de Economía y Competitividad from Spain under the CONSOLIDER-INGENIO 2010 program CSD2010-00064 reference, and the research program FPI BES-2011- 046199

Broadband low-noise GaN HEMT TWAs using an active distributed drain bias circuit

Modern communication and radar systems show an increasing demand for robust ultra-broadband amplifiers for low-noise applications. A set of three different 0.5 GHz to 20 GHz MMIC LNAs using a GaN HEMT technology with a gate length of 0.25 μm was designed and fabricated, each with a noise figure between 3 dB and 7 dB over frequency. Two designs with four and five FET cells feature approx. 10 dB and 11 dB broadband gain, while a third MMIC with a chain connection of both figures more than 20 dB of gain. A distributed active drain bias circuit substitutes large area or off-chip inductor structures and enables a full-MMIC chain connection of both TWA stages

Design methodology and performance analysis of a wideband 90º phase switch for radiometer applications

This paper presents the analysis, design, and characterization of a wideband 90º phase switch in Ka-band. The phase switch is based on two microstrip bandpass filters in which the commutation is performed by a novel single-pole double-throw (SPDT) switch. The analysis of π-network bandpass filters is provided, obtaining the phase difference and amplitude imbalance between filters and their scattering parameters; tested results show an average phase difference of 88.9º ± 5º and an amplitude imbalance of 0.15 dB from 24 to 37 GHz. The new broadband SPDT switch is based on a coplanar waveguide-to-slotline-to-microstrip structure, which enables a full planar integration with shifting branches. PIN diodes are used to perform the switching between outputs. The SPDT shows isolation better than 19 dB, insertion loss of around 1.8 dB, and return loss better than 15 dB. The full integration of the phase switch achieves a return loss better than 11 dB and insertion loss of around 4 dB over the band 26–36 GHz, with an average phase difference of 87.1º ± 4º and an average amplitude imbalance of 0.3 dB. It provides an excellent performance for this frequency range, suitable for radio-astronomy receivers.The authors would like to thank the Spanish Ministry for Science and Innovation for the financial support provided under the Project No. AYA2010–21766-C03–03 and the CONSOLIDER-INGENIO 2010 programme under Reference No. CSD2010–00064

Four-state full Q-band phase shifter using smooth-ridged waveguides

A novel four-state full Q-band waveguide phase shifter based on smooth-ridged sections is presented. The waveguide structure combines differential 90° and 180° phase shifters, whose combination provides the four-phase states (0°, 90°, 180°, and 270°) by appropriately controlling a set of millimeter-wave switches. Each differential phase shifter is performed using an E-plane continuous profile ridge to reach the 90° or 180° phase shift, respectively. The phase shifter module provides outstanding performance covering the full Q-band (33-50 GHz) with average phase results of 93.5°, 182.8°, and 270.6°.This work was supported by the Spanish Ministry of Economy and Competitiveness through the Consolider-Ingenio 2010 Program under Grant CSD2010-00064 and Grant ESP2015-70646-C2-2-R

Conmutador de fase 180º de banda ancha a 30 GHz

The design, assembly and characterization of a phase switch in the Ka-band based on PIN diodes is presented. This phase switch has provided a 20 per cent of bandwidth at 30 GHz and a phase shift around 180º. The phase switch has been made with a broadband hybrid coupler on microstrip technology and commercial PIN diodes HPND-4005 from Agilent. Two different techniques to adjust the phase shift have been applied. Input and output matching better than 13 dB, return losses lower than 3 dB and a phase shift from 160º up to 174º have been obtained from 27 to 33 GHz