1. These digitally tunable capacitors allow true computer-controlled impedancematching adjustments to RF/microwave circuits. Peregrine Semiconductor>

WHILE 2011 was another difficult year economically, RF/microwave companies sought new practical solutions to customers' needs through innovation and design refinements. As a result, the Top Products of 2011 lineup is quite impressive, even when compared with those of recent years. It represents a cross section of the industry's many different products, from semiconductor devices to full systems.

In terms of pure power, few systems could match the output of the model 10.5T2000M-16/1C solid-state amplifier system from Communication Power Corp. The large, rack-mount system delivers 32 kW output power across 16 channels from 40 to 450 MHz for pulsed-signal, magnetic-resonance-imaging (MRI) applications, helping MRI systems achieve a 10.5-T field strength. The amplifier system can also be switched from 16-channel mode to provide a single channel with 30 kW output power using its switch matrix and radial power combiner.

A number of 2011's Top Products helped advance circuit design by improving upon essential signal-processing functions. For example, the models HXG-122+ and HXG-242+ GaAs enhancement-mode pseudomorphic high-electron-mobility-transistor (EpHEMT) amplifiers from Mini-Circuits make it possible to extend the dynamic range of a system through their high linearity, without appreciable power consumption. The former operates from 0.4 to 1.2 GHz with a typical third-order intercept point (IP3) of +46 dBm while the latter spans 0.7 to 2.4 GHz with a typical IP3 of better than +46 dBm.

For receiver protection, the LM Series of surface-mount diode limiters from Aeroflex/Metelics can be used over frequency ranges as broad as 20 MHz to 8 GHz. They are fabricated using discrete diodes and hybrid-circuit manufacturing techniques, and can handle as much as 100 W CW power and 2 kW peak power. They are supplied in RoHS-compliant surface-mount packages measuring only 8 x 5 x 2.5 in.

Enabling sampling in portable devices, the HMCAD1520, HMCAD1511, and HMCAD1510 ADC family from Hittite Microwave Corp. is all this and more, delivering sample rates to 1 GSamples/s with 8-b resolution. All three feature programmable selection between single-, dual-, and four-channel operation, integrated cross point switch (analog multiplexer) array, and internal clock divider. Models HMCAD1510 and HMCAD1511 are 8-b ADCs designed for single-channel sampling rates with +1.8-VDC supplies, operating from 120 to 500 MSamples/s and 120 MSamples/s to 1 GSamples/s, respectively. The devices operate with internal 13-b resolution, allowing for a 1x to 50x digital gain range with no missing codes for digital gain settings through 32x.

Synergy Microwave's DCO and DXO series voltage-controlled oscillators (VCOs) achieve wide tuning ranges and low phase noise in compact surface-mount housings measuring just 0.3 x 0.3 in. The oscillators boast 2:1 tuning bandwidths from 500 MHz to 18 GHz; they are based on slow-wave printed coupled resonators which are relatively immune to vibration.

The PE64904 and PE64905 DuNE Digitally Tunable Capacitors (DTCs) from Peregrine Semiconductor Corp. are 5-b, 32-state digitally controlled variable capacitors in 2 x 2 mm, 10-lead QFN packages (Fig. 1). Fabricated on the firm's silicon-on-sapphire (SOS) process, these UltraCMOS devices are ideal for use in tunable filters to matching networks in amplifiers and antenna tuning. Available in series and shunt configurations, capacitance ranging from 0.7 to 4.6 pF in discrete 126-fF steps (a 6.6:1 tuning ratio) in series configuration and 1.1 to 5.1 pF in discrete 131-fF steps (a 4.6:1 tuning ratio) in shunt configuration. The quality factor (Q) for a shunt-configured DTC is about 35 for the lowest capacitance state at 1 GHz.

To satisfy a growing interest in gallium nitride (GaN) power transistors by commercial and military designers, M/A-COM Technology Solutions introduced discrete GaN-on-SiC power transistors as well as pallet amplifiers based on those transistors. Ideal for S-band radar, avionics, electronic- warfare (EW), and general-purpose applications, the 0.5-m transistors support pulsed applications through 3.5 GHz at peak power levels to 180 W. They are designed for drain voltage of 60 V.

The first two members of a line of single- and dual-mixer ICs from Analog Devices, models ADL5811 and ADL5812, hint at the promise of these passive mixer designs. These programmable ICs, which serve applications from about 700 to 2700 MHz, allow users to trade off different performance parameters, such as noise figure and spurious-free dynamic range (SFDR), to optimize system-level performance.

For pure switching speed, the SMS-DA direct-analog frequency synthesizer from Spinnaker Microwave has few peers. With a total tuning range of 1.25 to 18.0 GHz in 1-Hz steps, it achieves better than 350-ns tuning speed to switch from any one frequency to a second.

2. The compact frequency extender units used with the ME7838A Series of broadband VNAs simplify on-wafer S-parameter measurements from 70 kHz to 125 GHz. Anritsu Co.>

A large number of test instruments are on the 2011 Top Products list. For example, the VR5 HD Spatial Channel Emulator from Spirent Communications is a single-box means of creating test conditions for communications systems based on multiple-input, multiple-output (MIMO) antenna arrays. It can define unidirectional and bidirectional MIMO configurations as large as 4 x 4 in bidirectional emulations and 8 x 4 in unidirectional emulations, and can mimic as many as 24 signal paths per channel. Relative path loss can be set from 0 to 50 dB.

In September, Anritsu made noise with its introduction of the ME7838A Series of broadband vector network analyzers (VNAs) with coverage from 70 kHz to 125 GHz, ideally suited for on-wafer measurements of emerging millimeter-wave devices (Fig. 2). Millimeter-wave links, for example, are of interest to commercial designers developing short-range, high-data-rate systems, and are also being examined for use in military unmanned area vehicles (UAVs). The VNAs work with light-weight frequency extension modules that simplify on-wafer millimeter-wave measurements.

The flexibility of modular instrumentation, such as the model NI PXIe-5665 PXI signal/spectrum analyzer from National Instruments, is earning believers in this industry. These PXI-based modules can be swapped as needed for different measurement functions, including signal generation and analysis. The NI PXIe-5665 is a vector signal analyzer (VSA) with frequency range to 3.6 GHz, as well as highly accurate amplitude and phase responses.

The latest InfiniiVision 2000 and 3000 X-Series mixed-signal oscilloscopes (MSOs) and digital-storage oscilloscopes (DSOs) from Agilent Technologies provide general-purpose test capabilities at waveform update rates as fast as 1 million waveforms per second. The InfiniiVision 2000 X-Series oscilloscopes are available in bandwidths from 70 to 200 MHz, while the InfiniiVision 3000 X-Series scope models cover bandwidths from 100 to 500 MHz. Both series include MSOs, as well as DSOs with two or four analog channels. Rohde & Schwarz and Tektronix also introduced digital oscilloscopes of note in 2011, with the latter's MDO4000 series of instruments combining many of the features of an oscilloscope with those of a 6-GHz spectrum analyzer.

Measurements often involve isolating a signal of interest from those around it, and the MLBF series of benchtop YIG-tuned filters from Micro Lambda Wireless include bandpass filter models to 50 GHz and band-reject models to 20 GHz that can be remote controlled as part of an automatic-test-equipment (ATE) setup. The compact filters measure just 4 x 10 x 13 in. and include Ethernet and USB 2.0 interfaces. Bandpass filters provide 3-dB passbands from 15 to 500 MHz across frequency ranges as wide as 3 to 50 GHz, while the band-stop filters offer 3-dB notches from 100 to 150 MHz across frequency ranges as wide as 0.5 to 20.0 GHz.

Finally, simulation software was also advancing in 2011, with AWR's AWR 2011 suite demonstrating many of the latest trends in computer-aided-engineering (CAE) tools. This suite includes Microwave Office, the Analog Office, the Visual System Simulator (VSS), and the versatile AXIEM electromagnetic (EM) simulator. It also adds such features as group-design capability and asynchronous electromagnetic (EM) simulation.

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