USB Powers Compact RF Test Instruments

Jan. 19, 2011
The latest additions to a line of USB RF/microwave measurement devices include several power meters, vector modulators, and a set of synthesized signal generators capable of low-phase-noise performance.

ASSEMBLING AN automated test system once required costly instruments and controllers. But thanks to companies such as Telemakus, automated measurement systems can be created by plugging a Universal Serial Bus (USB) dongle into a personal computer (PC). The company recently added to its lines of USB test functions with new frequency synthesizers, vector modulators, and root-mean-square (RMS) power meters (see table).

Last year, the company unveiled several compact USB test cards (see Microwaves & RF, February 2010, p. 94), with product lines that included power meters, signal generators, single-pole, double- throw (SPDT) microwave switches, and a digital attenuator. All of the company's products are compatible with the USB 2.0 standard, which supports data transfer rates to 480 MB/s and the connection of as many as 127 USB devices through a USB hub.

The company's USB test instruments rely on a PC's display screen and processing capabilities to show and orchestrate RF/microwave measurements. All of the USB instruments are supported by simple graphical user interface (GUI) software that enables setting of controls and entering data points for measurements, typically running on PCs with Microsoft Windows XP or Windows Vista operating systems.

The latest batch of instruments includes a pair of vector modulators, two synthesized signal generators, a broadband laboratory amplifier, and several true RMS power meters. For example, the model TEV2700-45 RF vector modulator is ideal for vector signal measurements, beam-forming, and amplitude/ phase-correction applications. It accepts inputs to +23 dBm from 1800 to 2700 MHz and provides a full 360-deg. phase control range with 12-b resolution and 45-dB dynamic range. Input signals are fed to the TEV2700-45 via an SMA male connector, with outputs available at an SMA female connector. Signals suffer no more than 10 dB insertion loss as part of the modulation process, with 9-dB typical return loss.

The little USB vector modulator integrates 0.5-GB flash memory for installation files, test data, and other supporting documentation. It draws 150 mA at +5 VDC from a computer's USB port. Each vector modulator is calibrated at the factory at three frequencies, and more calibration points can be added by a user. An easy-to-use graphical interface allows both numerical data entry or the use of on-screen slider controls to enter data. The company also offers the model TEV1000-50 RF vector modulator with a frequency range of 700 to 1000 MHz and 50-dB dynamic range based on maximum input signal level of +23 dBm. It exhibits 1-dB compression at +14 dBm input power and has an input third-order intercept point (IP3) of +33 dBm. Model TEV1000-50 also provides a 360-deg. phase control range with 12-b resolution.

The frequency synthesizers are each stabilized by an internal 10-MHz crystal reference oscillator with excellent stability over temperature. Model TEG250-15 is the lowest-frequency member of the signal source group, with a tuning range of 140 to 250 MHz in steps as small as 1 kHz. It delivers +15 dBm output power across its bandwidth, with -118 dBc/Hz phase noise offset 100 kHz from the carrier. Spurious levels are typically -80 dBc. The tiny signal generator, developed as a clock source for high-speed analog-todigital converters (ADCs), includes an on/off power control and draws 150 mA from a +5 VDC supply.

For generating microwave test tones, model TEG10200-1 is the company's highest-frequency synthesized signal generator, providing +15 dBm from 9.3 to 10.2 GHz. It also uses an internal 10-MHz crystal reference oscillator capable of 2.5 PPM frequency stability from -40 to +55C. It achieves phase noise of -95 dBc/Hz offset 100 kHz from the carrier, with spurious levels of -75 dBc, second harmonics of -20 dBc, and third harmonics of -30 dBc. It draws 250 mA from a +5-VDC USB port. In addition, the company offers signal generators for frequency coverage of 700 to 1000 MHz (model TEG1000-10), 1800 to 2700 MHz (model TEG-2700-6), and 2700 to 3500 MHz (model TEG3500-8), all featuring phase noise of -105 dBc/Hz phase noise offset 10 kHz from the carrier. For the signal generators, a simple GUI supports the control of multiple USB frequency synthesizers for implementing multitone testing. The GUI allows a choice of tuning in steps of 1 kHz, 10 kHz, 100 kHz, and 1 MHz.

When it is necessary to boost broadband test signals, the company's new model TAMP6000-15 USB amplifier provides 15-dB gain from 100 MHz to 6 GHz with +19 dBm typical output power at 2 GHz and 1-dB compression. It has typical IP3 of +35 dBm at 2 GHz and draws 100 mA from a +5-VDC supply.

Telemakus also recently introduced several true RMS power meters, including model TED10200-45 with a 45-dB dynamic range from 9.3 to 10.2 GHz. RF power is measured using an integratedcircuit (IC) logarithmic detector. As with the other USB instruments, it includes 0.5 GB of flash memory, to store power calibration tables as well as measurement data. An internal temperature sensor maintains accuracy over temperature, and is accessible by users for their own calibrationsno calibration standards are needed. The power meter can handle inputs to +20 dBm at an SMA male connector with accuracy of 0.5 dB to +10 dBm. It runs at a sample rate of 10 Hz. The company also offers model TED6000-50 for 50 MHz to 6 GHz and model TED14500-45 for 14.0 to 14.5 GHz. To simplify connections to a PC, Telemakus has developed the model THUB7-1 hub, which connects as many as seven USB devices to one computer USB port.JB

Telemakus LLC, 13405 Folsom Blvd., Suite 502, Folsom, CA 95630; (916) 458-6346, FAX: (916) 983-8713, e-mail: [email protected], Or contact distributor RFMW Ltd. at (877) 367-7369,

About the Author

Jack Browne | Technical Contributor

Jack Browne, Technical Contributor, has worked in technical publishing for over 30 years. He managed the content and production of three technical journals while at the American Institute of Physics, including Medical Physics and the Journal of Vacuum Science & Technology. He has been a Publisher and Editor for Penton Media, started the firm’s Wireless Symposium & Exhibition trade show in 1993, and currently serves as Technical Contributor for that company's Microwaves & RF magazine. Browne, who holds a BS in Mathematics from City College of New York and BA degrees in English and Philosophy from Fordham University, is a member of the IEEE.

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