Thursday, 24 September 2009

Signal generator

New RF Vector Signal Generator provides Industry’s best Combination of high Throughput and low Phase Noise

Keithley Instruments has upgraded its popular RF Vector Signal Generator line for RF engineers with new capabilities that reduce signal generation times and enhance signal quality. In contrast with competitive signal generators, which typically force users to choose between best signal quality and maximum test throughput, the Model 2920A’s no-compromise design combines both capabilities in the same instrument. Patent-pending technology allows the Model 2920A RF Vector Signal Generator to support both frequency and amplitude switching rates that are significantly faster than any competitive system. Unlike systems optimized either for development or production, it is a cost-effective solution whether used on the bench for design verification testing or in production testing.

Continuing Technical Leadership in MIMO Testing
The Model 2920A is the latest addition to Keithley’s MIMO (Multiple-Input, Multiple-Output) testing system solutions. MIMO signals can be easily generated and analyzed by using Keithley’s SignalMeister™ RF Communications Test Toolkit software and Model 2820A Vector Signal Analyzers in conjunction with Model 2920As. When used in conjunction with the signal personalities provided in SignalMeister software, it is not only capable of generating pure signals but can generate impaired signals for in-depth receiver characterization and testing.
Model 2920A Applications
Applications include R&D, product development, and production testing of a growing range of wireless products such as femtocells, access points, mobile devices, wireless modules and air cards, and wireless chipsets. The Model 2920A’s operating mode flexibility makes it an excellent choice for MIMO device and system R&D applications, as well as in engineering education settings.

The Model 2920A, which provides signal generation bandwidth options up to 80MHz with a frequency range of either 10MHz–4GHz or 10MHz–6GHz, builds on the capabilities of Keithley’s Series 2900 signal generator line. It expands the Series 2900 line’s applications for testing wireless devices to today’s high throughput, complex modulation, and wide bandwidth wireless telecom standards, including LTE, GSM/EDGE, cdmaOne, cdma2000, W-CDMA, HSPA, HSPA+, LTE, WLAN, WiMAX, WiBro, TD-SCDMA, DVB (Digital Video Broadcast), and GPS (Global Positioning System).

The unit is optimised for calibrating and testing components such as amplifiers, filters, and wireless receivers thoroughly over their full range of performance at exceptional speed. Several major advances allow it to provide substantially higher test throughput than earlier signal generation options:

  • Industry’s fastest frequency tuning: A new, patent-pending technique that ensures fast settling of phase-locked loop synthesizers allows the Model 2920A to tune to a new frequency on a device under test’s (DUT’s) operating band in 300μs or less. Competitive products typically require 600μs or longer to tune to a new frequency.
  • Industry’s fastest amplitude switching: The Model 2920A provides electronic attenuation and a fast-tracking, automatic level control loop to stabilize quickly on a new power level, which allows switching to a new amplitude in as little as 150ms (compared to more than 500μs for competitive generators). This fast settling time speeds testing a device over its full power handling range.
  • Waveform switching in a single clock cycle: Because devices that operate on multiple standards require rapid switching between numerous complex signals during testing, the Model 2920A’s on-board arbitrary waveform generator includes a 100-megasample memory to hold large individual waveforms or multiple smaller ones. This deep memory, combined with the instrument’s speed-optimized list mode and a sequencer operating mode, supports switching from one waveform to another within a single processor clock cycle—even with waveforms based on different standards that use different modulation schemes.
  • High speed signal file transfers: The Model 2920A offers a direct link from its DSP processing circuit block to an external PC via a USB 2.0 bus that maximizes operating speed. In this high-speed Desktop Control Panel operating mode, an external PC assumes control of the Model 2920A, just as if it were the instrument’s on-board processor controller. This mode supports transferring signal files from a PC directly into the Model 2920A’s arbitrary waveform memory at 100Mb/sec for faster, simpler downloading of extremely large files (such as streaming video test signal files, signal files modified by channel models, and radar profile files). When combined with its high download speed and Keithley applications software, the Model 2920A can perform fast, efficient Dynamic Frequency Selection (DFS) conformance testing on WLAN access points. This test package allows verifying a device’s compliance with FCC, ETSI, and TELEC requirements related to ensuring that WLAN access point transmissions detect and do not interfere with government radar signals (such as weather radar or air traffic control radar).

    Users have the flexibility to create waveform files offline and download them into its arbitrary waveform memory using a USB memory stick or the GPIB or LAN interfaces. This transfer flexibility will be useful for those who prefer to employ third-party tools to create signal files, such as The MathWorks’ MATLAB® interactive programming environment.

    The Model 2920A’s enhanced speed performance doesn’t compromise its phase noise performance. Unlike competitive signal generators, which are typically designed to maximize either throughput (for production test applications) or signal purity (for design verification applications), it includes new capabilities that allow optimizing for whichever performance aspect is most critical for a specific application:

  • Ultra-low phase noise option: High signal purity is essential when creating complex HSPA+, 802.11n WLAN, 802.16e WiMAX, and LTE signals. To ensure the quality of these signals, the Model 2920A-UPN Ultra Low Phase Noise option provides phase noise ≤-135dBc/Hz at a 300kHz offset on a 2GHz carrier. That allows generating WCDMA signals with EVMs <0.85%. This option also permits the Model 2920A to generate 5.8GHz, 40MHz bandwidth WLAN 802.11n signals with an EVM of less than ‑43dB and WiMAX signals with a residual RCE (Relative Constellation Error) ≤-43dB. Just as important, the Model 2920A provides no-compromise tuning times as fast as 750µs when the low phase noise option is used.
  • Low amplitude range option: The Model 2920A’s wide signal range makes it ideal for testing a broad spectrum of receivers and components. The Model 2920A-LAR Low Amplitude Range option extends that range to allow the generator to output signals as low as ‑130dBm or as high as +13dBm. In addition, the Model 2920A offers excellent accuracy, repeatability, and stability specifications, so test system designers can set narrow limit bands in their test protocols, helping to ensure higher product quality:
    • Absolute amplitude accuracy of ±0.6dB (typically ±0.3dB) from
      -110dBm to +13dBm up to 3GHz
    • ±0.05dB relative amplitude accuracy (linearity)
    • ±0.05dB amplitude repeatability

    The Model 2920A’s combination of high speed and high quality signal generation performance makes its pricing even more competitive because users can perform multiple applications with the same instrument—from design verification testing to production testing—extending the usage of each unit purchased. Option prices, whether the ultra-low phase noise option or optional personalities tailored to various telecom standards, are also at or below the cost of competitive solutions. Orders are being taken now for delivery in six weeks.
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