System, method and apparatus for transmitting and receiving a transition minimized differential signal
The present invention is directed to a system, method, and apparatus to transmit/receive TMDS signals using general purpose differential transmitter and receivers. In an embodiment, the general purpose differential transmitter and receivers are designed to operate with differential signaling schemes such as LVDS and LVPECL. In one aspect, embodiments according to the present invention enable the re-configuration of existing and fully-characterized LVDS/LVPECL transmitter/receiver cells to support TMDS (using minimal sets of external components). This provides considerable cost and development time savings, thereby allowing the development of products much more expediently. In another aspect, embodiments according to the present invention provide interfacing methods and systems between differential signaling schemes such as LVDS/LVPECL and TMDS.
1 . A system for interfacing a Transition Minimized Differential Signaling (TMDS) transmitter and a Low Voltage Differential Signaling (LVDS)/Low Voltage Positive Emitter Coupled Logic (LVPECL) receiver, comprising:
a TMDS driver;
a LVDS/LVPCEL receiver; and
an impedance network coupled between said TMDS driver and said LVDS/LVPCEL receiver, wherein said impedance network steps down a common mode voltage of said TMDS driver to within a defined common mode voltage range of said LVDS/LVPCEL receiver.
2 . The system of claim 1 , wherein said impedance network controls a signal swing level of said TMDS driver to satisfy a signal swing threshold of said LVDS/LVPCEL receiver.
3 . The system of claim 1 , wherein said impedance network is a resistive network.
4 . The system of claim 1 , wherein said impedance network includes one or more resistive, capacitive, and/or inductive elements.
5 . The system of claim 1 , wherein said impedance network is located off-chip relative to an integrated circuit chip that includes said LVDS/LVPECL receiver.
6 . The system of claim 1 , wherein said impedance network is integrated with said LVDS/LVPCEL receiver in a single integrated circuit chip.
7 . A system for interfacing a Low Voltage Differential Signaling (LVDS)/Low Voltage Positive Emitter Coupled Logic (LVPCEL) transmitter and a Transition Minimized Differential Signaling (TMDS) receiver, comprising:
a LVDS/LVPCEL driver;
a TMDS receiver; and
an impedance network coupled between said LVDS/LVPCEL driver and said TMDS receiver, wherein said impedance network steps up a common mode voltage of said LVDS/LVPCEL driver to within a defined common mode voltage range of said TMDS receiver.
8 . The system of claim 7 , wherein said impedance network controls a signal swing level of said LVDS/LVPCEL driver to satisfy a signal swing threshold of said TMDS receiver.
9 . The system of claim 7 , wherein said impedance network is a resistive network.
10 . The system of claim 7 , wherein said impedance network includes one or more resistive, capacitive, and/or inductive elements.
11 . The system of claim 7 , wherein said impedance network is located off-chip relative to an integrated circuit chip that includes said LVDS/LVPECL driver.
12 . The system of claim 7 , wherein said impedance network is integrated with said LVDS/LVPCEL driver in a single integrated circuit chip.
13 . A method for interfacing a Transition Minimized Differential Signaling (TMDS) transmitter and a general-purpose receiver, comprising:
receiving a TMDS differential voltage signal from the TMDS transmitter;
decreasing a common-mode voltage of said TMDS differential voltage signal to within a defined common mode voltage range of the general-purpose receiver; and
controlling a swing level of said TMDS differential voltage signal to satisfy a signal swing threshold of the general-purpose receiver.
14 . The method of claim 13 , wherein a step-down impedance network is coupled between said TMDS transmitter and said general-purpose receiver.
15 . The method of claim 14 , wherein said step-down impedance network is integrated with said general-purpose receiver in a single device.
16 . The method of claim 13 , wherein said general-purpose receiver comprises a Low Voltage Differential Signaling (LVDS)/Low Voltage Positive Emitter Coupled Logic (LVPCEL) receiver.
17 . A method for interfacing a general-purpose transmitter and a Minimized Differential Signaling (TMDS) receiver, comprising:
receiving a differential voltage signal from the general-purpose transmitter;
increasing a common-mode voltage of said differential voltage signal to within a defined common mode voltage range of the TMDS receiver; and
controlling a swing level of said differential voltage signal to satisfy a signal swing threshold of the TMDS receiver.
18 . The method of claim 17 , wherein a step-up impedance network is coupled between said general-purpose transmitter and said TMDS receiver.
19 . The method of claim 18 , wherein said step-up impedance network is integrated with said general-purpose transmitter in a single device.
20 . The method of claim 18 , wherein said general-purpose transmitter comprises a Low Voltage Differential Signaling (LVDS)/Low Voltage Positive Emitter Coupled Logic (LVPCEL) transmitter.