C-PHY Transmitter, Receiver, and Protocol Solution
Tektronix C-PHY TX Essentials, C-PHYXpress, TMPC-CPHYVIEW, and Moving Pixel C-PHY Protocol solution provides one stop comprehensive C-PHY solution for conformance and characterization of Transmitter, Receiver, and Protocol Test requirements as per MIPI standards. C-PHY TX Essentials solution provides easy way to debug and characterize C-PHY data links. C-PHY TX application allows you to select electrical and timing measurements, as defined in MIPI C-PHY v1.0 specification.
- Supports de-embed and embed feature for three-port on either side (6-port parameter support for de-embedding)
- Measures the rise time and fall time of the DUT C-PHY signals.
- Performs both eye height and eye width measurements, and also verifies the eye diagram on C-PHY signals.
- Verifies that the static point common mode voltage VCPTX of the trio signal is within the transmitter limit.
- Verifies that the common-mode voltage mismatch (ΔVCMTPX) of the DUT Data Lane HS transmitter is less than the maximum conformance limit.
- Verifies that the common-mode level variation is between 50 MHz to 450 MHz.
- Verifies that the common-mode level variation is above 450 MHz.
- Measures the Intra-pair skew of the trio signal.
- Modifies limits in TekExpress for debug and characterization.
Simplified Receiver test setup:
Single setup to generate signal for C-PHY and D-PHY.
- Easy to calibrate and provide repeatable results.
- Direct synthesis method helps to create all types of stress with a single box.
100% Test coverage. C-PHYXpress application allows you to create C-PHY standard conformant test signals up to C-PHY v1.1 specifications.
Best-in-class AWG70000 Series with sampling rate of 50 GS/s with 10 bit vertical resolution, to provide best signal fidelity for C-PHY signal generation.
Ease of Use
C-PHYXpress provides batch processing to create multi-test scenarios for rigorous test requirements.
Receiver conformance test and beyond:
- C-PHYXpress application provides a platform to create a wide range of stimuli to test the device beyond specification.
- Program Rise time and fall time of Data, Program ESC, LP Command along with Programmable Stress as mentioned below:
HS mode stressors
Random jitter and deterministic jitter
Embed insertion loss and de-emphasis
Duty cycle distortion
LP mode stressors
eSpikeand minimum pulse TMIN-RX
Set up/hold time tolerance
Real-time skew control
Offline signal generation
C-PHYXpress application can work in offline mode or from PC, to control the AWG remotely and generate C-PHY signals.
Moving Pixel C-PHY Protocol Generator and Decoder:
C-PHY Protocol Generator:
Stand-alone instrument with simplified setup and operation.
- Supports MIPI C-PHY signaling up to 2.5 Gbps-per-lane, for 1 to 4 lanes.
- Provides independent channel and real time adjustments for voltage and skew.
- Supports up to C-PHY v1.0, CSI2 v1.3, and DSI v1.2 protocols.
- Provides automated video sequence construction according to the user-defined frame timing.
- Implements automatic image scaling, format conversion, and simple test pattern generation.
- Supports multi-message response capture using 4 KB buffer.
- Includes DSC binary support; optional DSC image compression support available.
Provides scripting and remote-control capability using .NET DLL.
Oscilloscope based C-PHY Protocol Decode:
- Supports decode of single MIPI C-PHY lane up to 2.5 Gbps.
- Decodes and displays CSI2 v1.2 or DSI2 v1.0 protocol packets, and C-PHY v1.1 signaling states/symbols.
- DSI support does not include DSC, LPDT, BTA, or peripheral command decoding.
- Cursors on oscilloscope linked to both directions of the decode window.
- Provides search and display filtering capabilities.
- Decodes, displays, and exports (under user control) captured video frames.
- Automotive camera and display
- Mobile camera and display
- Camera CMOS Image sensors
- Display Driver ICs
- Application processor for mobile devices
MIPI C-PHY transmitter test
MIPI ® C-PHY v1.0 provides throughput high performance over bandwidth limited channels for connecting to peripherals, including displays and cameras. This interface allows the system designers to easily scale the existing MIPI ® Alliance Camera Serial Interface (CSI-2) ecosystem to support higher resolution image sensors with less power consumption.
MIPI ® C-PHY and MIPI ® D-PHY are pin compatible, allowing connections to the companion device with either technology. C-PHY was designed to coexist on the same IC pin as D-PHY so that dual-mode devices can be developed.
MIPI C-PHY introduces 3-phase symbol encoding offering 2.28 bits per symbol to transmit data symbols on 3-wire lanes or trios, where each trio includes an embedded clock.
C-PHY signals have three levels and they are single-ended. They are represented as LineA, LineB, and LineC. At any given point in time, no signals are at the same voltage levels. The receiver side is differential and displays four different voltage levels; Strong 1, Weak 1, Strong 0, and Weak 0. The receiver however views either logic 1 or logic 0.
C-PHY clock recovery
C-PHY uses a unique mechanism for clock recovery. C-PHY 1.0 implements a custom clock recovery algorithm referred to asTriggered Eye. In this model, the first zero crossing of the four differential signals is used as a trigger point for clock recovery and to render the eye diagram.
The eye mask is optimally placed for maximum eye opening where the eye height is measured. Because of the triggered eye mechanism, all jitter at the trigger point (zero crossing) is allowed and reflected on the other side. Refer to the previousEye maskfigure.
C-PHY transmitter test measurements
For characterization, debugging, and margin testing some of the key measurements required in the High Speed mode include:
- Rise time
- Fall time
- Eye diagram
- AC common mode measurement
- DC common mode mismatch measurement
- AC common mode level variation from 50 MHz to 450 MHz
- AC common mode level variation above 450 MHz
- Intra-pair skew
C-PHY TX Essentials
Custom-triggered eye diagram
The following figure displays the C-PHY TX Essentials Test software being configured for a custom-triggered eye diagram, with auto mask position for optimal mask placement.
C-PHY TX Essentials
Eye diagram analysis for 3M UI
The Jitter and Eye diagram rendering performed over the entire record length helps designers to characterize the devices better by displaying anomalies of the device over an extended period. The software allows you to run the eye diagram analysis for 3M UI and overnight run for a detailed characterization.
Eye diagram analysis
Rise time/Fall time transition details
Each differential waveform has four transitions of interest, when characterizing the device:
- Strong to weak transition (S-W)
- Weak to strong transition (W-S )
- Weak to weak transition (W-W)
- Strong to strong transition (S-S)
The following figure shows the details for measuring the transitions.
Rise time transition details
Fall time transition details
Insertion loss and crosstalk
As part of characterizing the device, designers need to embed or de-embed insertion loss and crosstalk. This is supported using the filter files generated that uses the S4P/S6P or S-Parameter files, as shown in the following figure.
Insertion loss and crosstalk
Measuring intra-pair skew
The skew between trios, referred to as the intra-pair skew, is an informative test of interest to many design engineers. The following figure shows a report generated by the Tektronix C-PHY TX Essentials software that includes details and status of the intra-pair skew for 12 wire state combinations.
Signaling and termination
C-PHY signaling is similar to D-PHY. For instance, it dynamically switches from LP mode to HS Mode of the timing measurements defined for C-PHY are similar to D-PHY.
The following figure is from the MIPI Alliance C-PHY specification v1.0. It shows the structure of a C-PHY signal (HS data transmission in Burst).
C-PHY signal (HS data transmission in Burst)
To take measurements during this switchable termination mode, load boards or termination boards are needed. The physical setup for taking these measurements require an oscilloscope, probes, and a termination board.
The following figure shows the physical set up for HS measurements. Termination board and probes are not required for HS measurements, you can connect SMA cables directly.
SC-PHY High Speed measurements
C-PHY Rx calibration
The primary purpose of the C-PHY TX software is for transmitter characterization; the core measurements supported by this software are designed to be used for receiver calibration. The C-PHY receiver calibration, according to the CTS, recommends calibrating the eye diagram with the predefined rise time/fall time. This calibration includes support for DCD (Duty Cycle Distortion), as an important stress parameter which drives closure of the eye. The next step includes calibrating the C-PHY signal with impairment of the DC common mode and AC common mode noise. The generation of these stresses is supported using the Tektronix AWG 70000 Series Arbitrary Waveform Generator.
C-PHY Rx calibration
P7700 probe for MIPI C-PHY (C-PHY Essentials only)
The MIPI application requires a special type of probing because of different impedances in High Speed and Low Power modes. In High Speed mode, C-PHY signals are in terminated environment. In Low Power mode, C-PHY signals are operated in unterminated environment with single-ended signals. MIPI C-PHY has two main requirements for probing:
- Provide high impedance
- Differential and single-ended mode
The P7700 Series probe (C-PHY Essentials only) provides an active buffer tip, few millimeters away from the end of tip. This provides the best signal fidelity for MIPI C-PHY application along with flexible connectivity options.
The TriMode probe helps to create differential, single-ended, and common mode measurements accurately with the probe setup. This unique capability allows you to work more effectively and efficiently, switching between differential, single-ended and common mode measurements without moving the probe's connection points.
P7700 Series TriMode probe (C-PHY Essentials only)
You can be confident in the signal fidelity of your measurements. The innovative new probe design uses SiGe Technology to provide the bandwidth and fidelity needed today and in the future.
The P7700 Series TriMode probe (C-PHY Essentials only) architecture provides:
An active buffer amplifier on the tips with the probe input only 3.2 mm from the input
Excellent step response and low insertion loss up to 20 GHz
Low-DUT loading with 100 kΩ (DC) and 0.4 pF (AC) performance
The C-PHYXpress plugin creates C-PHY signals for High Speed, High Speed Burst, and Low Power content with worst-case impaired input signals.
The Receiver test solution consists of the following steps:
Generate a test signal to emulate the transmitter, including channel and noise impairments.
- Calibrate the signal as per the CTS requirement.
- Set up the Device for receiver test.
- Determine the Bit Error Rate in the given test condition.
The C-PHYXpress application addresses the first two steps and are described below:
Step 1: Generate a test signal to emulate the transmitter, including channel and noise impairments
The C-PHYXpress supports waveform generation for High Speed, Low Power, and Low Power-High Speed (LP-HS) mode as per C-PHY specification v1.1.
High Speed mode: The C-PHY v1.1 specification data rate is up to 3.5 Gbps in High Speed mode. As per the CTS, you need to emulate the channel effect in High Speed mode. C-PHYXpress application allows you to edit the data rate, rise time, pattern type, voltage level, and impairments to emulate the channel effect.
High Speed Mode
In High Speed mode, you can add various channel effects such as: Periodic Jitter (Pj), Random Jitter (Rj), Dynamic Skew (DCD), Sine Noise Amplitude, De-Emphasis, and S-Parameter file of Channel for Data signal.
High Speed with Jitter parameters
High Speed Jitter - Embed Channel effect
High Speed Jitter Mode - S-Parameter File
Low Power Mode
The C-PHY v1.1 specification data rate is up to 100 MHz in Low Power mode. The C-PHYXpress application allows you to edit the data rate, rise time, pattern type, voltage level, and impairments to emulate the channel effect.
Low Power Mode
The C-PHY v1.1 specification requires Sine/Square noise with eSpike noise.
The C-PHYXpress allows you to add Sync Word as per the specification with the timing parameters for Data.
Calibrate the signal as per CTS requirement:
Calibration of signal impairments provides calibration routines that are C-PHY standard specific. The objective of calibration is to compensate the patterns for specific jitter parameters. The typical parameters are Random, Periodic Jitter, and Amplitude. The procedure sequences through all the patterns and each pattern is calibrated independently. These values are used for the Jitter- controlled generation of patterns and are injected into the DUT during loopback.
For more details regarding calibration, refer to MOI document available inhttp://www.tek.com/mipi-0.
For more details, refer to theReceiver test specificationtable later in this document.
Batch mode allows you to create a library of compiled waveforms with incremental jitter values with a single click.
C-PHY Protocol generator
C-PHY pattern generator
The P339 is a stand-alone C-Phy Pattern Generator that features four data lanes made by The Moving Pixel Company (TMPC). Data rate operation is up to 2.5 Gb/s per wire and supports up to 12 wires. LP Voh, LP Vol, HS Voh, and Vol are adjustable. It is designed to run in conjunction with the CPhyGenCtl software.
The CPhyGenCtl application is the controlling software for the P339 CPhy Generator, made by The Moving Pixel Company (TMPC). Using the P339 C-Phy Pattern Generator, you can generate CSI protocol and pattern stimulus on a MIPI CPhy bus for receiver testing. This datasheet describes the use and operation of CPhyGenCtl and the corresponding behavior of the CPhy generator.
The CPhy generator is connected through USB to a host computer that runs the CPhyGenCtl software. It has the following capabilities:
- Supports one to four CPhy lanes, supporting frequencies up to 2.6 Gsym/s.
- Contains an internal pattern generator with 2 GB of program memory.
- Provides up to 15 ns of integer symbol lane skew, with fractional symbol lane skew below 1.5 Gsym/s.
- Provides real-time, per-lane, high and low voltage, and fine-adjustments for both LP and HS signals.
- Supports fine adjustment of CPhy bus timing.
- Provides 4 KB receive buffer for DUT LP response capture.
- Supports lane 0 LP contention detection.
- Implements arbitrary logical-to-physical lane output mapping.
- Comprehensive video support:
- Support for 3D stereoscopic frame construction (DSI 1.2).
- Purchase option for encoding and sending of DSC video frames (DSI 1.2).
- Common source input image file formats (jpg, png, tiff, gif), used for both video-mode and write memory commands.
- Automatic resizing of input images (in software) to fit the display or camera dimensions.
- Convenient image preview function in the GUI.
- Automated CSI/DSI video-mode frame generation based on user frame timing.
- Automatic partitioning of a single Write Memory command into multiple Write Memory command sequences.
- Video-mode frames can be added to the macros.
- Video-mode frames can be constructed with a single-bit error at a given line and bit position.
- Generic file command support:
- Uses a text file description to describe mixed low-level LP/HS transitions and packet definitions.
- Allows arbitrary data lane signal generation for conformance testing.
- Provides higher-level embedded commands for easy command definition, including HS burst entry and HS burst exit sequences. Includes automatic ECC and CRC generation.
- Support for low-level CPhy testing:
- Low-level test HS burst sequences using user-defined or PRBS data.
- Comprehensive CPhy protocol configuration for setting preamble, postamble, and sync sequences for each lane. Provides configuration for user bus timings, such as HSPreare, HSExit.
- Flexible bus timing specification in component units of ns, UI, and TLPX, allowing for frequency agile configurations.
- Powerful and easy-to-use GUI controls for command manipulation:
- Simple definition, naming, and sending of commands, including video-mode commands.
- Push-button interface for assigning and organizing commands, which are available for single-click sending.
- Macro definition for building and complex command sequences.
C-PHY oscilloscope-based decoder
The Moving Pixel Company CPhy Scope Decoder software is a single-lane CPhy and CSI2 protocol decoder from CPhy signal acquisitions from an oscilloscope.
The software runs on a Microsoft Windows 7 host connected to the oscilloscope, using the remote-control capability of the oscilloscope to control real-time acquisition.
The main functions of this software include:
- Provides real-time oscilloscope acquisition and control of one CPhy lane using three channels. The saved binary waveform files can be loaded and disassembled.
- Post-process the acquisition data to provide DPhy/DSI/CSI2 protocol disassembly views of communication on the link.
- Provides the views which are similar in look-and-feel to a logic analyzer type display.
- Provides extensive functions and manipulations for viewing, filtering, and searching the captured data.
- Builds video frames from decoded packets, including a frame summary listing that provides statistics, navigation, viewing, and saving of images.
- Checks and reports many types of errors, including illegal state transitions, invalid symbol sequences, packet header, and payload CRC errors.
- Correlate any event in the disassembly back to acquired waveforms on the oscilloscope using the zoom window and cursors.
C-PHY Signal Capture on an oscilloscope
All specifications apply to all models unless noted otherwise.
- Test parameters
Parameter group Parameter name Range Default Units Ref levels Reference levels Absolute, Percentage Percentage NA Reference level-High (%) 70 to 90 (in %) 40 to 60 (in Absolute) 80 (in %) 58 (in Absolute) % or V Reference level-Low (%) 10 to 30 (in %) -60 to -40 (in Absolute) 20 (in %) -58 (in Absolute) Reference level-Hysteresis (%) 5 to15 (in %) 5 to 25 (in Absolute) 10 (in %) 10 (in Absolute) Clock Settings Clock recovery method EXPEDGE
EXPEDGE NA Signal Type CLOCK
CLOCK Clock Edge RISE
RISE Loop bandwidth (MHz) 1 to 10 4 MHz MaskHitType Auto
Auto NA Others Accumulation True
True NA Eye Height Percentage 10 to 90 50 % Hysteresis 5 to 15 10 %
Minimum system requirements
- Operating system
- Windows 7, 64-bit
- DPO/MSO TekScope v22.214.171.124 or later and DPOJET version is 126.96.36.199 and above
- Software requirements
Microsoft .NET 4.0 Framework
Microsoft Excel 2002 or above
Microsoft Internet Explorer 6.0 SP1 or later
Adobe Reader 7.0 or equivalent software for viewing portable document format (PDF) files
If TekExpress is installed on a Tektronix oscilloscope, TekExpress uses a virtual GPIB port to communicate with oscilloscope applications. If external GPIB communication devices such as USB-GPIB HS or equivalent are used for instrument connectivity make sure that the Talker Listener utility is enabled in the DPO/DSA/MSO oscilloscope GPIB menu. For ease of use, connect to an external (secondary) monitor.
Transmitter test specification
- C-PHY base specification
- Revision 1.0
- C-PHY conformance specification
- Revision 1.0
- High Speed Essentials
- Rise Time
- Fall Time
- Eye Diagram
- DC Common Mode measurement
- AC Common Mode Mismatch measurement
- AC Common Mode Level Variation between 50 MHz and 450 MHz
- AC Common Mode Level Variation above 450 MHz
- IntraPair Skew
Receiver test specification
- C-PHY conformance specification
- Revision 1.1
- C-PHY base specification
- Revision 1.1
- Group 1 tests
- LP-RX VOLTAGE AND TIMING REQUIREMENTS
- LP-RX Logic 1 Input Voltage (VIH)
- LP-RX Logic 0 Input Voltage, Non-ULP State (VIL)
- LP-RX Input Hysteresis (VHYST)
- LP-RX Minimum Pulse Width Response (TMIN-RX)
- LP-RX Input Pulse Rejection (eSPIKE)
- Group 2 tests
- LP-RX BEHAVIORAL REQUIREMENTS
- LP-RX Initialization period (TINIT)
- ULPS Exit: LP-RX TWAKEUP Timer Value
- Data Lane LP-RX Invalid/Aborted Escape Mode Entry
- Data Lane LP-RX Invalid/Aborted Escape Mode Command
- Data Lane LP-RX Escape Mode, Ignoring of Post-Trigger-Command Extra Bits
- Data Lane LP-RX Escape Mode Unsupported/Unassigned Commands
- Group 3 tests
- HS-RX VOLTAGE AND JITTER REQUIREMENTS
- HS-RX Amplitude Tolerance (VCPRX(DC), VIHHS, VILHS)
- HS-RX Differential Input High/Low Thresholds (VIDTH, VIDTL)
- HS-RX Jitter Tolerance
- Group 4 tests
- HS-RX TIMER REQUIREMENTS
- HS-RX T3-TERM-EN Duration
- HS-RX T3-PREPARE Tolerance
- HS-RX T3-PREBEGIN Tolerance
- HS-RX T3-PROGSEQ Tolerance
- HS-RX T3-POST Tolerance
- Test procedure
- Refer to MOI document for detailed test procedure.
C-PHY Essentials Transmitter Test licensing
|Opt. C-PHY||C-PHY Essentials Transmitter Solution (Node Locked)|
|DPO-FL-C-PHY||C-PHY Essentials Transmitter Solution (Floating)|
|DPO-UP C-PHY||C-PHY Essentials Transmitter Solution|
|TMPC-CPHYVIEW||C-PHY Scope based Single Lane Decoder|
Required instruments and accessories
|DPO/MSO70000C/DX/SX, Option DJA||6 GHz and above real-time oscilloscope||1|
|P7313 or P7700 (C-PHY Essentials only)||Differential active probes||3|
|TMPC-CTB||C-PHY termination board (supports up to 4 lanes)||1|
CPHYXpress receiver setup
Option PRECOMFL-SS01 or PRECOMNL-SS01 on AWG
|10 bit, 2 G Samples record length, two channel arbitrary waveform generator.|
|AWGSYNC01DPO-UP||Hub for synchronizing multiple AWGs|
|TMPC-MDC4500-4B||MIPI signal conditioning accessory for the AWG 70000|
|DPO70000C with opt DJA , Probe, and Termination Board (For calibration purpose)||6 GHz and above real-time scope is required for Calibration|
|CPHYNL-SSV1||C-PHY synthesis software on AWG|
|PSPL 5915 with Opt.100PS||100 ps Filter (SMA male-to SMA male)|
|Phase-matched SMA cable||174-5771-xx|