Solutions for Cellular Repeaters and Automotive Compensators

Aug. 22, 2023
Guerrilla RF's Jim Ahne covers the basics of the RF signal chain as well as some of the features and benefits of the company's recent 0.5-W amplifiers and digital step attenuators.

This video is part of our IMS 2023 coverage.

In Guerrilla RF, wireless design engineers find a reliable partner when it comes to MMICs for infrastructure applications. In addition to a quick overview of the company's portfolio, which includes amplifiers with and without bypass, RF power detectors, mixer/amplifier combos, RF switches, and digital step attenuators (DSAs), we were updated on some of the company's latest offerings by Guerrilla RF's Jim Ahne.

One of these recent launches is the first of the company's new line of indium-gallium-phosphide (InGaP) HBT 0.5-W power amplifiers, the GRF5607 (703 to 748 MHz) and GRF5608 (746 to 830 MHz). Given their frequency ranges, these amplifiers are made for 5G infrastructure applications in the n12, n14, n18, n20, and n28 5G NR bands.

They'll give designers some 26 dBm of linear power boost from 40 to +85°C. The amplifiers maintain an adjacent channel leakage ratio (ACLR) of more than -45 dBc and an error-vector magnitude (EVM) of <1.2% with no need for linearization schemes such as digital pre-distortion (DPD). The ACLR metric without DPD suits these amplifiers for cellular applications such as home/commercial repeaters and boosters, femtocells and picocells, and cable-loss compensators for use with automotive "shark-fin" antennas.

In the video, Ahne also mentions Guerrilla RF's new DSA, the GRF6402. The GRF6402 is a SPI-controlled, bidirectional, 31.75-dB-range DSA that provides precise stepping in 0.25-dB increments. The device’s serial interface utilizes three externally defined address bits, allowing up to eight unique devices to share a common SPI bus. In addition to supporting traditional serial programming, the GRF6402 also includes a special Rapid Fire selection pin that allows the device to be immediately switched into a pre-defined attenuation state.

In terms of performance, the GRF6402 can cover from 50 MHz to 6 GHz while still maintaining precise and monotonic gain stepping. Glitching has been minimized to <2 dB for all steps. The device delivers up to 30.5 dBm of IP0.1dB, 55 dBm of IIP3, and a low IL of less than 1.4 dB at 2 GHz.

Here's a transcript of the video (it has been edited for clarity):

Hi, good afternoon. My name is Jim Ahne and I’m the VP of Products for 5G as well as Automotive at Guerrilla RF. Today I'm going to talk to you about some of our solutions that are targeted for cellular repeaters and boosters found in residential and commercial applications as well as within automotive compensators, or com-PEN-sators, as they’re sometimes called.

Guerrilla RF offers numerous components including gain blocks, digital step attenuators (DSAs), driver amplifiers, power detectors, linear PAs, and LNAs that cater to the uplink and downlink chains found in these different applications. Now you might be asking yourself, where are these found and where would I see these in everyday life?

The repeaters and boosters are becoming popular in applications where you're challenged from a propagation perspective within homes or within businesses. Oftentimes, when looking upon a building, you might see an antenna like this called a donor antenna. These are often placed outside the home and pointed toward a base station or a cellular tower.

The donor antenna’s signal comes inside and into this unit, where all the electronics are housed, including these LNAs, gain blocks, drivers, and PAs. From here, after the signal has been amplified, it ends up going to a distribution antenna placed in the house.

That antenna propagates the signal to cell phones and other peripherals scattered in various rooms. The key here is that you're getting through the “Faraday cage,” as we like to call it, of the home, which restricts the transmission of the signal from outside the home to inside.

There’s also the same type of application within automotive. In this block diagram, you can see it's the exact same components in a different environment. You're probably familiar with the shark-fin antennas that you find on most new vehicles rolling off the assembly lines these days.

Those antennas on car roofs serve different applications like Sirius XM or Satellite Digital Automotive Radio Service (SDARS) that includes GPS and cellular; the latter can be used for eCall applications. In Europe, it’s very popular to have these compensators located there, too. In such applications, you’ll typically place your phone in a cradle alongside your seat where there may also be wireless charging.

There's also an antenna that helps couple the signal from your phone, sends it through cabling up through the side pillar. In the pillar, you'll find the same electronics as in residential and commercial applications, but in a much smaller form factor.

Inside, you'll find Guerrilla RF components again, the same ones shown in that block diagram. Once that signal is amplified, it goes out to the shark-fin antenna. Again, it's the same type of application but different end market. Some of the new products that Guerrilla RF has introduced this week include a new family of power amplifiers.

Last year at the show, we talked about the 0.25-W family. We have over 10 different variants that span from roughly 600 MHz all the way up to 4.2 GHz, which covers virtually all 4G/5G bands in use today.

One of the other products we announced today is the first of the 0.5-W series. These 0.5-W amplifiers have the same footprint and layout as the 0.25-W series, but doubling the power, which enables customers to cover about 40% more range now with that additional output power capability. Another product that we recently released is this DSA, the block shown here in purple. This is a 7-bit device with 31.75 dB of range and 0.25-dB steps.

In this DSA, one of the new innovations is a thing we dubbed Rapid Fire. It addresses a delay found in any serially controlled DSA when inputting a SPI transaction, whether it's an 8-bit or a 16-bit SPI transaction. If you clock in that SPI command serially at a 3- to 10-MHz rate, it takes a while to get the device to switch from state to state.

With Rapid Fire, we hold two distinct states within a device. We have two registers that hold a primary and a secondary state. By executing this command through a dedicated bit, we can basically flip-flop or toggle between the primary and the secondary states.

It's beneficial if you want to share a common DSA between the receiver up and down link path. And you can then flip-flop. So, one mode or primary would be, say, for the uplink and the secondary would be for the downlink.

In addition to that, these devices are handy if you want to protect stages that are downstream from the DSA. Let's say this antenna gets knocked off or there's some type of a mismatch that could potentially damage that final-stage power amplifier. With this Rapid Fire feature, you can quickly activate a high attenuation state to kill the signal before the PA gets damaged. These are two of the main use cases that we've come across with our customers.

For more information, visit the company's website

For more IMS 2023 coverage, visit our digital magazine.

About the Author

David Maliniak | Executive Editor, Microwaves & RF

I am Executive Editor of Microwaves & RF, an all-digital publication that broadly covers all aspects of wireless communications. More particularly, we're keeping a close eye on technologies in the consumer-oriented 5G, 6G, IoT, M2M, and V2X markets, in which much of the wireless market's growth will occur in this decade and beyond. I work with a great team of editors to provide engineers, developers, and technical managers with interesting and useful articles and videos on a regular basis. Check out our free newsletters to see the latest content.

You can send press releases for new products for possible coverage on the website. I am also interested in receiving contributed articles for publishing on our website. Use our contributor's packet, in which you'll find an article template and lots more useful information on how to properly prepare content for us, and send to me along with a signed release form. 

About me:

In his long career in the B2B electronics-industry media, David Maliniak has held editorial roles as both generalist and specialist. As Components Editor and, later, as Editor in Chief of EE Product News, David gained breadth of experience in covering the industry at large. In serving as EDA/Test and Measurement Technology Editor at Electronic Design, he developed deep insight into those complex areas of technology. Most recently, David worked in technical marketing communications at Teledyne LeCroy, leaving to rejoin the EOEM B2B publishing world in January 2020. David earned a B.A. in journalism at New York University.

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