Keithley upgrades RF vector signal analyzer, introduces upconverter
The Model 2820A provides a 40-MHz signal-acquisition bandwidth with a frequency range of either 400 MHz to 4GHz or 400MHz to 6GHz.
-- Test & Measurement World, 6/16/2009 9:10:00 AM
Keithley Instruments at the International Microwave Symposium announced that it has upgraded its RF vector signal analyzer line with new capabilities that reduce signal-acquisition and measurement times. Keithley also highlighted its new Model 2891-IQ upconverter, which provides support for transceiver testing by processing analog I and Q baseband signals for testing a transceiver’s transmitter, as well as processing analog I and Q output signals for testing a transceiver’s receiver.
The new Model 2820A RF vector signal analyzer, which provides a 40-MHz signal-acquisition bandwidth with a frequency range of either 400 MHz to 4 GHz or 400 MHz to 6 GHz, builds on the capabilities of Keithley’s Series 2800 signal analyzer line. It expands the line’s applications for testing wireless devices to today’s high throughput, complex modulation, and wide bandwidth wireless telecom standards.
Three major advances allow the Model 2820A to provide substantially higher testing speed:
• Fast frequency switching: The Model 2820A can tune to a new frequency in just 250 μs, significantly reducing total transmitter test time when testing a device that operates over a wide frequency band or multiple frequency bands.
• Fast sequence testing: The Model 2820A employs a single-command, multi-operation technique to minimize transmitter calibration and performance test times. With a single setup, a wide range of measurements can be made on transmissions at multiple frequencies, multiple power levels, and using multiple standards. Both power measurements and modulation quality measurements, such as EVM and I, Q offset, are all included in a single data capture operation.
• High speed data transfers: A new technique allows transferring large amounts of demodulated IQ data from the instrument to a PC for analysis via the USB bus at speeds better than 100 Mbps, 25 times faster than the previous generation of analyzers.
The Model 2820A offers two different modes of operation: conventional front-panel control and remote PC control. A “Desktop Control Panel” mode makes the aforementioned high-speed transfers possible by letting the PC control the instrument and act as its processor. This mode bypasses the instrument’s internal processor, so data is transferred directly from the DSP-processing blocks to the 100-Mbps USB bus. In this mode, the instrument’s front panel display is disabled and the information is displayed on the PC’s screen. Users can interact with the PC display and have full control over the instrument, just as if they were operating it through its front panel. They can capture a WiMAX burst, transfer it to a PC, and process it by computing nine measurements, including EVM measurements, in as little as 80 ms. Power measurements can be transferred at a speed of less than 700 µs per measurement. The Model 2820A also has the ability to post-process continuous blocks of data bursts, so users can capture a series of EDGE Evolution bursts without any time-gaps, then post-process each burst in series, performing demodulation analysis in less than 10ms per burst.
Just as important, this enhanced speed does not compromise measurement performance; in fact, it has been improved significantly:
• Ultra-low phase noise option: A new synthesizer design allows the Model 2820A to provide low phase noise performance. For example, the phase noise is less than 140 dBc/Hz at a 300-kHz offset on a 2-GHz carrier, which allows the dynamic range of EVM measurements to be as low as -48dB for 20-MHz WLAN 802.11n measurements. When the ultra-low phase noise option is used, the Model 2820A can tune to a new frequency in as little as 1 ms. Users can switch between maximum measurement performance and the maximum speed via software with this option.
• DANL (displayed average noise level): In addition to the ultra-low phase noise option, the Model 2820A’s DANL is better than -143 dBm/Hz with the built-in pre-amp enabled.
In addition to the existing demodulation and signal analysis options for GSM, EDGE, EDGE Evolution, WCDMA, HSDPA, cdma2000, WLAN, and WiMAX transmissions, the Model 2820A can now analyze 3GPP Release 7 HSPA+ signals with a new optional personality. Each preconfigured personality provides a robust set of measurements, instrument settings, and test limits customized for the various standards. These personalities save configuration time and minimize the potential for operator error. When addressing MIMO (multiple-input, multiple-output) applications, the instrument’s 100-Mbps data-transfer rate allows researchers to conduct advanced MIMO studies in such areas as channel sounding and beam forming. Furthermore, the Model 2820A offers time and phase synchronization of MIMO signals. Multiple Model 2820As can be synchronized to capture multiple transmission streams with high accuracy. Signal acquisition synchronization jitter is less than or equal to 250 ps, so users can be confident that time delays between signal streams are the result of transmitter issues or channel conditions, rather than instrument latency. Keithley MIMO test configurations that include Model 2820A instruments can test MIMO devices with up to eight antennas. MIMO signals can be generated and analyzed by using Keithley’s SignalMeister RF Communications Test Toolkit software and Model 2920 vector signal generators in conjunction with Model 2820As.
The price of the Model 2820A RF vector signal analyzer is $22,950 USD.
Upconverter supports transceiver test, simplifies test system design
Keithley also highlighted its new Model 2891-IQ upconverter, which provides support for transceiver testing by processing analog I and Q baseband signals for testing a transceiver’s transmitter, as well as processing analog I and Q output signals for testing a transceiver’s receiver.
The Model 2891-IQ converts single-ended baseband analog I and Q signals from a signal generator into differential output signals to provide input signals for testing transceivers with differential baseband I,Q inputs. On the receiver side, it converts the receiver’s down-converted differential I and Q signals into a modulated, up-converted signal for receiver performance testing by an RF signal analyzer. It speeds and simplifies designing transceiver test systems because it interfaces with both RF transceivers and with Keithley’s Series 2900 RF vector signal generators and Series 2800 RF vector signal analyzers.
The Model 2891-IQ contains gain adjustments so that it can interface with a wide variety of wireless chipsets and devices. Furthermore, the Model 2891-IQ can interface with RF transceivers with either single-ended or differential inputs. Its EVM floor of 41 dB, even for wideband 40MHz-bandwidth 802.11n signals, makes it possible to use the Model 2891-IQ when making high quality modulation measurements.
This instrument’s compact size allows it to be located close to the wireless DUT, which helps minimize loading, even on high-impedance devices, and maximizes signal bandwidth. Similarly, the selectable 50-Ω/100-kΩ input impedance of the Model 2891-IQ’s inputs allows it to connect to high-impedance devices with minimal signal loss. The instrument’s IQ modulator provides excellent signal fidelity, allowing the DUT’s receiver signals to be measured without noise floor or spurious signal interference from the instrument itself. For example, the Model 2891-IQ’s sideband suppression is less than 51 dBc.
The instrument is controlled through a USB connection and programmed with a simplified SCPI command set. An easy-to-use software control panel provides intuitive access to these commands. Signal differential offsets may be set and adjusted and modulator gain set. A nonvolatile EEPROM allows storing and recalling ten user instrument states.
The price of the Model 2891-IQ upconverter is $5000.
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