Advanced test signals for the on-wafer HBT measurements were generated with the help of Agilent's Connected Solutions. The concept is simple: use the modeling power of one of the industry's leading software simulation tools to create advanced waveforms, and then have the software control hardware instruments to actually generate those signals. In the case of the HBT measurements with the Maury HGT™ systems, the software was Agilent-EEsof's popular Advanced Design System (ADS) suite of Electronic Design Automation (EDA) tools and the hardware was the company's line of high-performance signal sources, including its ESG arbitrary waveform generators (see figure). Connected Solutions applications make it possible to use the wide range of signal waveform models in the ADS Wireless Libraries to create and analyze test signals for emerging signal formats and to provide simulated base-band functionality for performing research and development (R&D) coded bit-error-rate (BER) and packet-error-rate (PER) measurements on RF and mixed-signal designs.
The ADS Wireless Libraries help designers accelerate the time to market for their emerging wireless designs. These libraries can be used to create real-world test signals for signal formats such as mobile and fixed WiMAX and 3GPP LTE, by downloading ADS-simulated in-phase/quadrature (I/Q) data to an ESG arbitrary waveform generator. Flexible simulation capability can also be used to introduce impairments (such as multipath or fading) into real-world test signals for system-level testing. Test signals to be modeled can also be "fed" to the ADS software by capturing the output of a device under test (DUT) with a signal analyzer, oscilloscope, or logic analyzer and the processing this captured signal data with ADS.