2891-IQ
The Model 2891-IQ Upconverter enables
complete testing of a transceiver by processing
analog I and Q baseband signals for the transmitter and processing analog I and Q output signals from the receiver. The Model 2891-IQ takes
single-ended baseband, analog I and Q signals
from a signal generator and converts the signals
to differential output signals to provide a signal
for transmitter testing. On the receiver side, the
Model 2891-IQ converts the down converted
differential I and Q signals into a modulated, up
converted signal for receiver performance testing
by an RF signal analyzer.
The Model 2891-IQ easily interfaces with the
Keithley Series 2900 RF Vector Signal Generators
and Series 2800 RF Vector Signal Analyzers to
design fast, compact transceiver test systems.
Figure 1 shows a typical configuration for testing
a transceiver.
• Excellent Error Vector Magnitude
(EVM): ≤–41dB for 802.11n
devices
Model 2920
Vector Signal Generator
with baseband IQ outputs
Model 2891-IQ
• Accepts single-ended or
differential inputs
I
• USB-controlled with SCPI
instruction set
Q
• Modulator gain adjustments for
interfacing to a wide variety of
wireless chipsets and devices
Transceiver Under Test
I
Single-Ended-to
Differential
Converter
TX
Q
Model 2820
Vector Signal Analyzer
RX In
I
Modulator
RX
Q
• Selectable input impedances
• Easy interface with Keithley
vector signal generators/signal
analyzers for fast, compact
transceiver test systems
TX Out
Baseband upconverter
SideforText
wireless device testing
Upconverter
USB Control
Figure 1. Typical transceiver test configuration. The Model 2920 Vector Signal Generator
supplies single-ended, analog baseband, I and Q waveforms to the transceiver-under-test’s
transmitter. The Model 2891 IQ Upconverter converts the I and Q waveforms into differential
signals to be compatible with the differential inputs of the transceiver-under-test. The
transceiver’s transmitter output is routed through the SPDT switch to the Model 2820 Vector
Signal Generator for analysis. The transceiver’s receiver is tested by supplying a RF signal from
the vector signal generator. The receiver’s analog I and Q output waveforms are connected to
the Model 2891 IQ Upconverter’s modulator which upconverts the signal to a frequency that
will enable the vector signal analyzer to analyze the receiver’s output waveforms.
Applications
• Transceiver chipset testing
• Transceiver module and subassembly testing
• Wireless device testing
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The small size of the Model 2891-IQ is ideal for getting close to the wireless device under test. This
minimizes loading even on high impedance devices and maximizes signal bandwidth. Similarly, the
selectable 50W/100kW input impedance of the Model 2891-IQ inputs allows it to connect to high
impedance devices with minimal signal loss.
The Model 2891-IQ’s high performance IQ modulator provides excellent signal fidelity, allowing the
device-under-test’s receiver signals to be measured without noise floor or spurious signal interference
from the Model 2891-IQ Upconverter. For example, the Model 2891-IQ’s sideband suppression is
below 51dBc.
(U.S. only)
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Alternatively, the transceiver’s transmitter output can be looped back into the receiver’s input
for a combined test of both transceiver circuit blocks.
2891-IQ
Upconverter
Ordering Information
Baseband upconverter
SideforText
wireless device testing
2891-IQ Upconverter
The Model 2891-IQ is controlled through a USB connection and programmed with a simplified SCPI
command set. Signal differential offsets may be set and adjusted and modulator gain set. In addition,
ten user instrument states may be saved and recalled in the non volatile EEPROM. Figure 2 shows the
software control panel for the supplied Model 2891-IQ control software.
Accessories Supplied
CD-ROM containing the
2891-IQ, USB Drivers, Control
Program and User Manual
100–240 VAC to 24VDC Power
Supply and AC Line cord
USB Cable
10.16cm × 10.16cm (4 in. ×
4 in.) SMB cables for use
in loopback testing
Modes of Operation
• Baseband single-ended to
differential conversion
• Differential or single-ended
baseband up-conversion to
622.1MHz RF Frequency
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Figure 2. Control software setup display with SCPI commands shown.
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(U.S. only)
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2891-IQ
Upconverter
2891-IQ Specifications
Power to supplied AC/DC converter: 100–240VAC; 50–60Hz ; 10VA max.
Interface: USB 2.0 Full Speed Compatible, USB B-style connector.
CE EMC compliance: EU Directive 2004/108/EC; EN 61326-1: 2006; EN 61000-3-2: 2006;
EN 61000-3-3: 1995/A1 2001, A2 2005.
CE safety compliance: CE; EU Directive 2006/95/EC, EN 61010-1: 2001.
Calibration: 2-year.
Environment (for indoor use only):
18° to 28°C specified operating, unless otherwise noted.
0° to 50°C operating survival, non-specified operation.
–25°C to 65°C non-operating (AC power off) storage.
Altitude: 2000 meters above sea level maximum specified operating.
Cooling: Convection.
Mechanical vibration and shock: MIL-PRF-28800F CL3 random vibration, 3 axes
DIMENSIONS, WEIGHT: 58mm high × 130mm wide × 185mm deep (2.3 in. × 5.1 in. ×
7.3 in.). Weight: 1kg (2.2 lb.).
Warranty: 1 year.
Upconverter Output Performance 1, 2, 3, 4:
Waveform 1: 40MHz WLAN, 802.11n:
EVM: –41dB RMS.
Waveform 2: Single 18MHz Offset Tone:
Unwanted Sideband Suppression: –51dBc.
Carrier Suppression: –68dBc.
1.
2.
3.
4.
Performance data is characteristic, which is the mean value of units tested at 25°C.
The 2891-IQ is optimized for each specific waveform type.
Tested using calibrated vector source and Keithley Model 2810 as vector receiver.
Test setup is with 1V peak differential signal.
2891-IQ Baseband Section (I and Q)
Input Ports 5: A & B (I & Q) Inputs: ±2.0Vp max.
Input Port Impedance:
Impedance High: 100kW.
Impedance Low: 50W.
Output Level:
Differential Output: Unity gain with differential termination of 100W.
Output Port Impedance:
I&Q Differential Outputs: 100W.
Offset Adjustment:
Output Offset Adjustment Range: ±3.5V DC+AC waveform maximum.
Small Signal Bandwidth:
–0.1dB, 0.2V peak-peak: 130MHz.
Input and Output Connectors: SMB.
SPECIFICATION NOTES: Specifications describe the configuration or instrument’s warranted
performance. Typical and characteristic values are not warranted.
Characteristic (mean or expected value):
Characteristic values are nominal performance that units are expected to have under the
following conditions:
• Ambient operating temperature of 23°C, unless otherwise noted.
• After a warm-up time of 30 minutes and waveform calibration at ambient temperature.
This performance is not warranted.
5. Absolute maximum input is ±5 volts DC+AC on any input pin.
Model 2891-IQ
Side Text
specifications
GENERAL SPECIFICATIONS
2891-IQ Up Conversion Modulator Parameters
Modulator Gain Ranging 6:
Input Voltage for Full Modulation (Differential): 0.24 to 1.5Vp.
Attenuator: 127 steps.
Attenuator Step Size: 0.125dB.
Attenuator Range: 0–15.875dB.
Input Offset Adjustment Range: ±4.095V.
Input Port Impedance:
Impedance High: 100kW.
Impedance Low: 50W.
Input Connectors: SMB.
6. Absolute maximum input is ±5V DC+AC on any input pin.
2891-IQ RF Output Parameters
Carrier frequency 7: 622.10MHz (tolerance and drift depends on 10MHz reference).
Maximum RF Output Power: 9dBm CW maximum.
Output impedance: 50W, AC coupled.
Return Loss @ 622.1MHz: 16dB.
Connector Type: SMA.
2891-IQ External Reference Input Parameters
Model 2891-IQ rear panel
External Reference Input 7:
Input Frequency: 10.0MHz.
Input Impedance: 50W, AC coupled.
Input Signal Level: –3dBm to +10dBm.
Connector Type: SMB.
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7. A low noise, precision frequency reference input is required for operation and maximum performance.
(U.S. only)
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2891-IQ
Signal analyzer for Side
RF communications
Text
testing
Upconverter
Specifications are subject to change without notice.
All Keithley trademarks and trade names are the property of Keithley Instruments, Inc.
All other trademarks and trade names are the property of their respective companies.
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© Copyright 2009 Keithley Instruments, Inc.
Printed in the U.S.A.
No. 3022
03.10.09