GVIF Technology for Automotive Applications
High-Speed Differential Pair Digital
Interface Technology:
"GVIF" (Gigabit Video Interface)
The Shift to Digital in Image Transmission
High-definition digital transmission
In the LCD display market, where screen
sizes continue to grow and wide-screen has
become the mainstream, digital interfaces
have come to be widely used to connect
Blu-ray and DVD players to the display.
Compared to analog, digital interfaces
show almost no color mixing or resolution
degradation and can transmit images with
high definition. (See figure 2.)
At the same time, there are growing
demands for higher resolution in map display
and the ability to enjoy high-definition video
on the monitors used with in-car navigation
systems, and the switchover to digital is
progressing rapidly.
Furthermore, the places where digital
interfaces can play a role are expanding
to include not only the navigation monitor,
but the rear seat entertainment monitor
that allows passengers in the back to enjoy
movies and back and side monitors used to
improve safety. (See figures 1 and 3.)
Gigabit Video Interface (GVIF) is a unique
Differential pair digital interface
Thin, light, and long cables
High noise resistance, low electromagnetic interference
Includes copyright protection functions
ARIB standard compliance
*
" GV I F " i s a t r a d e m a r k o f S o n y
Corporation.
Figure 1
Automotive Entertainment and Interfaces
Figure 2
Sony technology that takes advantage
of the features of the differential pair
digital transmission format to provide an
environment in which high-definition images
can be transmitted over a thin, light, and
long cable.
Differential Pair Digital Interface
GVIF is an interface standard developed
by Sony to transmit image signals from
sources such as a car navigation system
main unit or a DVD/Blu-ray player to a flat
panel display. (See figures 4 and 5.) GVIF
transmits uncompressed serial data at
speeds up to 1.95 Gbps. Unlike many other
digital interfaces that use multiple differential
pairs in their cable, GVIF transmits over
a single differential pair. As a result, the
cable is thin (under a 4 mm diameter) as
shown in figure 6, and since there are only a
small number of connections, the connector
size and mounting area can be compact
as well.
Resolution Comparison Between Analog
and Digital Transmission
Analog Transmission (NTSC)
Rear seat entertainment display
Lane keeping assist
stereo camera
Car navigation/DVD/BD
Camera ECU
Rear camera
Display
Enlarged
Digital Transmission (GVIF)
Vehicle vicinity verification
improvement cameras
Enlarged
In automotive applications, where space
is particularly limited and it is desired to
reduce the total weight, these features
are significant advantages. Since a single
differential pair cable is used, there is no
skew between the differential pair signals,
and constraints on the reception circuit are
minimized.
At the same time, the speed of transmission
needs to be increased, and issues such
as long distance transmission and
electromagnetic interference must be
addressed as well. These issues are
controlled in a balanced and high-level
manner by the GVIF ICs. Transmission
distances up to ten meters are possible. At
the same time as transmitting 24-bit color
data with EGA, VGA, WVGA, SVGA, Dual
VGA, or XGA resolution, GVIF also supports
HDCP (High-Bandwidth Digital Content
Figure 3
GVIF Application Example
(GVIF automotive camera;
under development)
Protection System) content protection
technology. By using a GVIF transmission
IC that encodes the content together with a
GVIF reception IC that decodes the content,
digital video data with copyright protection
can be transmitted over a single differential
pair cable.
Multiplexing and Coding
To make transmission using a thin, light,
and long transmission line possible, GVIF
multiplexes several signals together. The
signals required for image transmission are
the RGB (24 bits) signal and the horizontal
and vertical sync signals. GVIF multiplexes
these together for transmission. Since
transmission is performed using a selfsynchronizing clock technique, a separate
clock line is not required. It is desired that
Figure 4
image transmission include some form of
content protection to protect the copyrights
of the owners of digital content. In GVIF,
a signal used for content protection is
multiplexed together with the video signal,
and there is no need to add special ICs for
content protection.
GVIF uses a unique encoding/decoding
technology for this multiplexing. The GVIF
encoder uses the characteristics of the
video signal, which consists of the RGB
signal, the sync signals, and control signals,
for encoding to achieve a high transmission
efficiency. (See figure 7.) This also allows
the encoder and decoder circuits to have
a simple and compact structure.
The signals multiplexed over GVIF are
not limited to only these signals. Although
upstream signals from the receiver IC to
the transmitter IC are required for HDCP
Figure 6
GVIF Application Example
(car navigation system)
Display
Navigation system main unit/
DVD/BD player
GVIF receiver IC
GVIF
Video data
GVIF transmitter IC
Figure 5
GVIF Source Device
Graphic
controller
MUX
CONTROL
GVIF Sink Device
GVIF
transmitter
PLL
GVIF
receiver
240-1950M bps
Pixel data
CLOCK
De
MUX
PLL
HDMI
*
HDMI (High-Definition Multimedia Interface) is
a trademark or registered trademark of HDMI
LLC.
Figure 7
GVIF Application Example (block diagram)
Pixel data
CLOCK
GVIF versus HDMI Cable
CONTROL
Display
controller
High Transmission Efficiency
GVIF Encoder
Pixel clock period
RGB
(24b)
VS, HS,
DE, CNTL
(4b)
Serial
bit stream
30b 30b
C
C
H
C
C
30b encoded RGB
6b header +
from 24b DATA 24b raw RGB DATA
authentication, GVIF handles these upstream
signals by multiplexed transmission.
Furthermore, signals set up by the user can
also be multiplexed, allowing bidirectional
communication∗¹ over a single differential
pair.
High-speed serial signals are strongly
distorted by cable attenuation. For GVIF,
whose transmission speed is in the 2 Gbps
class, the influence of this phenomenon
is significant. To deal with this cable
attenuation, GVIF includes an active
adaptive equalization circuit in the receiver
IC. This active adaptive equalization
circuit detects the cable's distortion and
automatically forms an optimal waveform.
The cable equalization circuit included in
GVIF reproduces a waveform close to the
waveform near the transmitting terminal.
Since this circuit can optimally compensate
for the attenuation that occurs without
external adjustment, it is possible to use
either a long transmission cable or a cable
with a comparatively high attenuation (a
thin cable). (See figure 8.)
∗1 Upstream signals are only supported by the
CXB1463R-W and CXB1464R-W.
Figure 8
High Noise Resistance, Low
Electromagnetic Interference
Cable Equalization
GVIF Receiver IC Cable Equalization
Receiver IC Input Signal Waveform
File Control Setup Measure
Acquisition is stopped.
40.0 GSa/s 60.0 kpts
1
On
The GVIF ICs were designed with the idea of
being used in multiple stages in a repeater
connection, and adopt a circuit structure that
is not easily influenced by external jitter. A
FIFO circuit is provided in the clock input
stage used for acquiring externally input
video signals and the IC-internal circuits
that high-speed signals pass through are
all implemented as differential circuits. As
a result of these and other efforts, the GVIF
ICs have a structure that is strongly resistant
to clock jitter and power supply noise. EMI
emissions from the GVIF systems meet the
requirements for class 5 as stipulated in
the CISPR 25 Edition 3.0 standard, "Radio
disturbance characteristics for the protection
of receivers used on board vehicles, boats,
and on devices – Limits and methods of
measurement" created by the Comite
International Special des Perturbations
Radioelectriques (International Special
Committee on Radio Interference). (See
figure 9.)
150 mV/
Analyze
2
Utilities
On
Post-Cable Equalization Waveform
Help
11:00 AM
3
8GHz Standard BW
On
4
On
File Control Setup Measure
Acquisition is stopped.
40.0 GSa/s 60.0 kpts
1
1/
On
150 mV/
Analyze
2
Utilities
On
Help
10:59 AM
3
8GHz Standard BW
On
4
On
1/
1T
More
(1 or 2)
Delete
All
H
103 ps/
0.0 s
0
T
More
(1 or 2)
0.0 mV
Color Grade Scales
1 17
Signal: 1.95 Gbps
Cable length: 10 m
?
18 34
35 68
69 136
137 272
273 544
1T
545 1089
Delete
All
H
103 ps/
0.0 s
0
T
0.0V
Color Grade Scales
1 16
?
17 32
33 65
66 131
132 263
264 526
527 1052
Copyright Protection
The GVIF ICs implement HDCP, which
performs content encryption and device
authentication over a single differential
pair GVIF communication line. The GVIF
transmitter IC provides functions that
encrypt the plain video signal output
from the content source and transmit the
encrypted content on the GVIF, and the
GVIF receiver IC provides functions that
decode the encrypted content that was
transmitted over the GVIF and output plain
video data to the display. Since these ICs
also include the control circuits necessary
for these functions, users can implement
systems that have HDCP functions simply
by connecting the content providing source
(such as a DVD player or car navigation
system) to the GVIF transmitter IC and
connecting the content receiving side (a
display) to the GVIF receiver IC.
Note that GVIF was formally recognized for
use as a digital video output from terrestrial
Figure 9
GVIF IC Lineup
Sony provides an extensive lineup of GVIF
ICs, including the CXB1457R/CXB1458R
developed for car navigation systems, the
CXM4017R/CXM4018R, which include
HDCP copyright protection functions for
video signals that require content protection,
and the CXB1463R-W/CXB1464R-W, which
include back channel functions (bidirectional
user data communication functions) to
handle touch panel control and similar
functions.
CISPR 25 Electromagnetic Interference Measurement Results
Figure 10
Future Developments
GVIF aims at transmission of high-definition
content over thin, light, and long cables
based on the concept of digital transmission
over a single differential pair. At the same
time it also introduces copyright protection
and support for improvements in digital
limitations in the future.
In the future, to allow GVIF to handle an
even wider range of content, Sony will
aim for even higher speeds to support
higher definition in automotive displays
and applications as well as audio data
for the increasing diversity in automotive
entertainment. Sony also thinks that GVIF
can be evolved to function as an interface
not only in automotive applications, but in
a variety of other areas as well.
GVIF IC Lineup
HD
Electromagnetic Interference Levels
NEXT GVIF
XGA
]m/VµBd[ leveL
80
60
40
20
0
Ð20
10
digital broadcast tuners for the Japanese
market at the April 2010 ARIB (Associated
of Radio Industries and Businesses)
standardization meeting.
CXM4017R
CXM4018R
CXB1463R-W
CXB1464R-W
Pe value for class 5
Peak
Horizontal 30 to 2500 MHz
100
Frequency [MHz]
1000
10000
WVGA
QVGA
CXB1457R
CXB1458R
Back channel support
GVIF
HDCP
Audio