Designers of digital-radio front ends now have a pair of powerful measurement tools at their disposal. The model N5343A digital-radio frequency (DigRF) V4 exerciser and N5344A analyzer modules from Agilent Technologies support the DigRF V4 standard for communications between mobile baseband and RF/microwave integrated circuits (ICs). The modules allow instantaneous generation of realistic stimulus signals and analysis of results from a radio's front-end circuitry to speed testing on digital radios and its associated circuitry and ICs.

The DigRF V4 standard, driven by the Mobile Industry Processor Interface Alliance, describes a high-speed digital serial bus and is a key enabling technology for fourth-generation (4G) cellular technologies such as Long Term Evolution (LTE) and WiMAX systems. Because of the multitude of communications standards and protocols in use among commercial and military digital-radio designs, validation testing becomes more complex — especially when trying to perform many different tests with a handful of instruments.

For example, the challenges for the RF design team begin with packetized digital in-phase/quadrature (I/Q) and control data being transferred between baseband ICs and RF/microwave ICs over the DigRF interface. Traditionally, spectrum analyzers have been used to perform modulation measurements using an analog I/Q link between the baseband and RF chips. The Agilent test instrument modules allow measurements to be made on the DigRF digital serial interface, with or without the RFIC and/or baseband sections. For RFIC test, the exerciser simulates a baseband IC; for baseband-IC test, it simulates an RFIC.

Agilent's DigRF test scheme helps to ensure that the design under test operates in compliance with the DigRF V4 revision 1.0 protocol specification. With it, designers gain insight into the DigRF link and protocol state machines and verify that the packets' structure is compliant with the standard. Agilent's N5343A DigRF V3/V4 exerciser provides insight into digital-RF signals that range from individual digital bits to I/Q-modulated RF signals (see figure). The exerciser allows engineers to work in the domain (digital or RF) and abstraction level (physical or protocol layer) of their choice to quickly characterize RFICs and rapidly solve cross-domain integration problems.

Agilent’s N5343A DigRF V3/V4 exerciser analyzes digital-RF signals from individual digital bits to I/Q-modulated RF signals.

Digital designers use the digital user interface to stimulate the DigRF interface at the link and protocol layer; they can observe system behavior with full packet-decoding capabilities. RF designers use Agilent's Signal Studio or ADS software for signal generation, and its VSA analysis software with a signal analyzer, signal sources, and the DigRF test system, to take consistent measurements across both the digital and analog interfaces of their RFICs.

Agilent's DigRF test scheme starts with a Windows XP-based personal computer (PC) acting as controller with host software. An N5302A two-slot or N5304A four-slot chassis connects to the PC via a local-area-network (LAN) connection. The chassis houses the N5343A exerciser module and/or the N5344A analyzer module. When paired with the N5345A and/or N5346A probe systems, either or both modules create a high-performance measurement system.

Agilent's dual-capture technology helps DigRF developers save time, money, and bench space. Before now, performing baseband-IC and RFIC emulation required an analyzer and exerciser to monitor transmit and receive packets. Dual capture eliminates the need for an analyzer for this application. It allows as much as 512 MB signal generation memory, 512 MB capture memory, or an option to distribute 512 MB capture memory within specified ranges.

In support of the N5343A exerciser and N5344A analyzer, the Agilent N5345A and N5346A active probes provide high-sensitivity testing at the gigabit speeds used in DigRF V4 testing but with extremely low capacitive loading (less than 0.15 pF). Design engineers can choose between the N5345A mid-bus probe with soft touch technology for fast probing on prototype boards and N5346A flying leads probing solutions, which enable effortless monitoring of DigRF V4 links in space-constrained designs. DE

Agilent Technologies, Electronic Measurements Group, 5301 Stevens Creek Blvd., MS 54LAK, Santa Clara, CA 95052; www.agilent.com/find/rdx.