VIDEO SERIES
Local oscillator and GHz clocks requirements in radio applications systems with LMX2594
This training series discusses the key requirements of local oscillators in microwave/RF and GHz clocks in radio applications. The topics covered establish the key relationships between the requirements of a signal source and its impact on a radio system. After this training, you will be armed with the ability to understand the system requirements of your customer and how they pertain to a signal source so you can engage with your customer in a very meaningful way. We will make clear simple links between phase noise and error vector magnitude (EVM) / reciprocal mixing, spurs and undesired responses, Jitter and SNR / noise figure, Synchronization and coherent receivers/phase array antenna, Sysref and deterministic latency. LMX2594 is a high-performance signal source targeted at these applications with purpose-built features.
Introduction: Local oscillator and GHz clocks requirements in radio systems with LMX2593
Presenter(s)
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Hello, and welcome to a presentation from Texas Instruments. My name is Simon, and today we'll talk about synthesizer or signal source, their key specification, and how these impact a local oscillator application or clocking a high-speed data converter.
At Texas Instruments, I'm an application manager. And the pictures below you see are from an event called The Big Climb. It's a fundraising event for the Leukemia and Lymphoma Society. It's big fun, and it's raising money for a very good cause. The following is a summary of the presentation. If you wish to read that summary, please pause the video now.
Local oscillator and gigahertz clocks requirement in radio application systems with LMX2594. LMX2594 is a 15 gigahertz synthesizer that will be used as an example throughout this presentation.
The presentation will be divided into four sections. After a brief introduction, we'll talk about the key specification of a signal source, how they impact radio performance. And finally, we'll go and find phase noise specification in a data sheet using LMX2594. You are currently watching video number 1. There will be four more videos describing the following topic.
The first time the phase lock loop was described was in 1932 in a paper by Henri de Bellecize in the French journal [FRENCH]. You can see the cover of the magazine on the right-hand side. And Mr. Bellecize was trying to build a synchronous receiver. However, it's not until a TV application that the phase lock loop was widely used where a need for sync of the vertical and the horizontal scan.
Nowadays, phase lock loop is used just about everywhere to multiply a frequency, to generate signal sources with excellent quality, or to lock multiple sources together. You can even use the phase lock loop to reduce the noise on a dirty signal or a noisy signal.
Let's introduce 2594 and its key specification. It is a 15 gigahertz wideband synthesizer. And the phase lock loop, or the PLL, is capable of 110 dBc per hertz at 100 kilohertz offset at the very top frequency of 15 gigahertz carrier frequency. With this sort of phase lock loop performance, we can integrate the noise from 100 hertz to 100 megahertz and obtain integrated RMS jitters smaller than 50 femtosecond.
Besides these great specifications, there are multiple features that are worth mentioning. The synthesizer has the ability to synchronize the output to the input, meaning to establish a deterministic phase relationship from the output to the input. It can be done on the output of either, but can also be done on the delta sigma engine, when used in fractional mode. There's also a very fast calibration in less than 25 microseconds. And finally, output B on the device can be repurposed to be used as a sys ref or sync in the application JESD204B standard.
If you want to learn more about 2594, please visit ti.com, and you'll find all the resources that you need. I would like to point out three links. There's a link for simulation software called PLLatinum Sim. There's a link for acquiring an evaluation card so you can make your full assessment of 2594. And finally, the evaluation card comes with a software so you can fully control the device when you're doing your evaluation. And the software is called TiCS PRO.
I could talk all day long of how this device is good, but I thought I'd mention or quote a few feedback from three customers. First customers says you guys knock the wind out of everybody here. Second customer-- from memory, this is the best device I've seen, period. And finally, the last customer says wow, 45 femtosecond RMS in a 6x6 millimeter chip. Do you guys realize? So that says a lot about what our customer thinks of LMX2594.
And this level of performance is highlighted here. This is an 8.8 gigahertz frequency. And you can see the phase noise from 100 hertz to 100 megahertz. The integral of that phase noise is right around 45 femtosecond. And I can show here 45 femtoseconds.
I'm now going to stop here, and we'll come back with the next section, which is the key specification of a single source.
