Tektronix Inc. today announced what it calls the industry’s first commercially available oscilloscope-based solution for MIPI C-PHY physical layer transmitter characterization and debugging. The new solution allows engineers developing next-generation camera technologies using the C-PHY 1.0 interface to conduct in-depth analyses, debugging, and characterization of their designs.
Published in September 2014, the MIPI C-PHY standard presents a number of significant test and measurement challenges. The most significant is the use of three-level signaling that is transmitted as a single-ended signal over three wires. The receiver, however, sees these signals as differential. This requires a unique clock-recovery mechanism to plot the eye diagram for analysis, which must work even under stressed eye conditions. Tektronix C-PHY Essentials, a new analysis and debugging software solution for C-PHY testing, fully supports the demanding C-PHY test requirements.
“With an up to 17.1-Gb/s data rate over a nine-wire interface, C-PHY provides the performance needed for high-megapixel-count image sensors along with low power consumption,” said Brian Reich, general manager, Performance Oscilloscopes, Tektronix. “Our solution for C-PHY transmitter testing allows engineers to detect issues early on in the product-development phase and confidently assures transmitter devices’ performance and interoperability.”
Among the early implementers of C-PHY is OmniVision Technologies Inc., a developer of advanced digital imaging solutions. OmniVision’s new OV23850 and OV21840, both being 20+ megapixel image sensors designed for the next-generation of flagship smartphones, have implemented the C-PHY interface under the current specification. Using the C-PHY Essentials analysis software, OmniVision and Tektronix were able to successfully validate and characterize the C-PHY interface used on the two new sensors.
“OmniVision is excited to have Tektronix’s oscilloscope-based C-PHY Essentials software for validating the next generation MIPI interface. With its three-wire signaling, C-PHY represents a significant design and test challenge,” said Paul Gallagher, senior director of marketing and business development at OmniVision. “With the help of Tektronix C-PHY Essentials, we were able to easily set up cameras utilizing the OV23850 and OV21840 sensors and confirm the C-PHY interface’s compliance with the MIPI specification.”
Receiver characterization
While the C-PHY Essential software is designed for TX characterization, it can also be used by designers for receiver calibration. For receiver calibration, a user needs the ability to make various rise- and fall-time measurements and calibrate to a stressed eye with different impairments such as DCD as recommended by the C-PHY compliance test specification. As such, C-PHY TX analysis software can assist designers with receiver calibration through use of the eye diagram analysis function.
Working with solution partner The Moving Pixel Co., the Tektronix C-PHY solution includes a four-lane C-PHY traffic generator, single-lane oscilloscope based C-PHY protocol decoder, and C-PHY termination board. The traffic generator can be also used for functional validation of the receiver. The protocol decoder is the industry’s first C-PHY decoder that runs on an oscilloscope. The Moving Pixel Co. also offers a four-lane termination board that supports C-PHY and D-PHY, the industry’s first with support for both of these PHYs on the same board.
