Analog behavior modeling for 3-phase signaling

Abstract

System, methods and apparatus are described that model analog behavior in a multi-wire, multi-phase communications link A digital signal representative of a physical connection in a communications link and a virtual signal characterizing a three-phase signal transmitted over the physical connection are generated. The virtual signal may be configured to model one or more analog characteristics of the physical connection. The analog characteristics may include voltage states defining the three-phase signal. The analog characteristics of the physical connection include at least three voltage states corresponding to signaling states of the three-phase signal.

What is claimed is: 
     
         1 . An apparatus, comprising:
 at least one processing circuit configured to model a signal transmitted over a physical connection in a communication link, wherein the signal is modeled using:
 a digital signal that represents logic states of the signal transmitted on the physical connection; and 
 a virtual signal that represents one or more analog characteristics of the physical connection, the analog characteristics including at least three valid voltage states, each voltage state corresponding to a voltage level associated with the physical connection, 
   wherein the at least one processing circuit is configured to characterize the signal transmitted over the physical connection by the virtual signal selecting between at least three modes of operation of the physical connection, wherein the physical connection is in a high-impedance state or an undefined state when an inactive mode of operation is selected, and   wherein the communication link carries a signal that has at least three phases.   
     
     
         2 . The apparatus of  claim 1 , wherein three valid voltage states are defined for the signal. 
     
     
         3 . The apparatus of  claim 2 , wherein one of the at least three valid voltage states is an undriven state, wherein only one physical connection in the communication link is in the undriven state when the communication link is in an active mode of operation. 
     
     
         4 . The apparatus of  claim 2 , wherein the virtual signal includes at least one bit that selects between one or more modes of operation of the physical connection. 
     
     
         5 . The apparatus of  claim 4 , wherein the communication link includes three physical connections, each physical connection communicating a different phase of a three-phase signal when an active mode of operation is selected, and wherein each of the three physical connections is in the high-impedance state in the inactive mode of operation. 
     
     
         6 . The apparatus of  claim 4 , wherein the one or more modes of operation include a high-speed mode and a low-speed mode. 
     
     
         7 . The apparatus of  claim 1 , wherein the digital signal comprises a first binary bit that selects between a first voltage state and a second voltage state. 
     
     
         8 . The apparatus of  claim 7 , wherein a voltage level of the second voltage state is selected by the virtual signal. 
     
     
         9 . The apparatus of  claim 7 , wherein:
 the signal that has at least three phases switches within a voltage range bounded by a maximum voltage level and a minimum voltage level;   the first voltage state is defined as the minimum voltage level; and   the voltage level of the second voltage state is selected by the virtual signal as either the maximum voltage level or an intermediate voltage level that is greater than the minimum voltage level and less than the maximum voltage level.   
     
     
         10 . The apparatus of  claim 7 , wherein:
 the signal that has at least three phases switches within a voltage range bounded by a maximum voltage level and a minimum voltage level;   the first voltage state is defined as the maximum voltage level; and   the voltage level of the second voltage state is selected by the virtual signal as either the minimum voltage level or an intermediate voltage level that is greater than the minimum voltage level and less than the maximum voltage level.   
     
     
         11 . The apparatus of  claim 1 , wherein the virtual signal characterizes analog behaviors of the physical connection when the communication link is operated in a high-speed mode that are different from analog behaviors of the physical connection when the communication link is operated in a low-speed mode of operation. 
     
     
         12 . The apparatus of  claim 11 , wherein the analog behaviors of the physical connection include a rise time or a rate of rise time between signal states on the physical connection. 
     
     
         13 . A method for simulating digital systems, comprising:
 modeling a signal transmitted over a physical connection in a communication link, wherein modeling the signal includes:
 generating a digital signal that represents logic states of the signal transmitted on the physical connection; 
 generating a virtual signal that represents one or more analog characteristics of the physical connection, the analog characteristics including at least three valid voltage states, each voltage state corresponding to a voltage level associated with the physical connection; and 
 characterizing the signal transmitted over the physical connection by the virtual signal selecting between at least three modes of operation of the physical connection, wherein the physical connection is in a high-impedance state or an undefined state when an inactive mode of operation is selected, 
   wherein the communication link carries a signal that has at least three phases.   
     
     
         14 . The method of  claim 13 , wherein the voltage states include three valid voltage states. 
     
     
         15 . The method of  claim 14 , wherein one of the at least three valid voltage states is an undriven state, wherein only one physical connection in the communication link is in the undriven state when the communication link is in an active mode of operation. 
     
     
         16 . The method of  claim 14 , wherein the virtual signal includes at least one bit that selects between one or more modes of operation of the physical connection. 
     
     
         17 . The method of  claim 16 , wherein the communication link includes three physical connections, each physical connection communicating a different phase of the at least three phases when an active mode of operation is selected, and wherein each of the three physical connections is in the high-impedance state in the inactive mode of operation. 
     
     
         18 . The method of  claim 16 , wherein the one or more modes of operation include a high-speed mode and a low-speed mode. 
     
     
         19 . The method of  claim 13 , wherein the digital signal comprises a first binary bit that selects between a first voltage state and a second voltage state. 
     
     
         20 . The method of  claim 19 , wherein a voltage level of the second voltage state is selected by the virtual signal. 
     
     
         21 . The method of  claim 19 , wherein:
 the signal that has at least three phases switches within a voltage range bounded by a maximum voltage level and a minimum voltage level;   the first voltage state is defined as the minimum voltage level; and   the voltage level of the second voltage state is selected by the virtual signal as either the maximum voltage level or an intermediate voltage level that is greater than the minimum voltage level and less than the maximum voltage level.   
     
     
         22 . The method of  claim 19 , wherein:
 the signal that has at least three phases switches within a voltage range bounded by a maximum voltage level and a minimum voltage level;   the first voltage state is defined as the maximum voltage level; and   the voltage level of the second voltage state is selected by the virtual signal as either the minimum voltage level or an intermediate voltage level that is greater than the minimum voltage level and less than the maximum voltage level.   
     
     
         23 . The method of  claim 13 , wherein the virtual signal characterizes analog behaviors of the physical connection when the communication link is operated in a high-speed mode that are different from analog behaviors of the physical connection when the communication link is operated in a low-speed mode of operation. 
     
     
         24 . The method of  claim 23 , wherein the analog behaviors of the physical connection include a rise time or a rate of rise time between signal states on the physical connection. 
     
     
         25 . An apparatus, comprising:
 means for modeling a signal transmitted over a physical connection in a communication link, wherein the means for modeling the signal is configured to:
 generate a digital signal that represents logic states of the signal transmitted on the physical connection; and 
 generate a virtual signal that represents one or more analog characteristics of the physical connection, the analog characteristics including at least three valid voltage states, each voltage state corresponding to a voltage level associated with the physical connection; and 
   means for characterizing the signal transmitted over the physical connection by the virtual signal selecting between at least three modes of operation of the physical connection, wherein the physical connection is in a high-impedance state or an undefined state when an inactive mode of operation is selected,   wherein the communication link carries a signal that has at least three phases.   
     
     
         26 . A processor-readable storage medium having instructions stored thereon which, when executed by a processing circuit, cause the processing circuit to:
 generate a digital signal that represents logic states of the signal transmitted on a physical connection of a communication link;   generate a virtual signal that represents one or more analog characteristics of the physical connection, the analog characteristics including at least three valid voltage states, each voltage state corresponding to a voltage level associated with the physical connection; and   characterize the signal transmitted over the physical connection by the virtual signal selecting between at least three modes of operation of the physical connection, wherein the physical connection is in a high-impedance state or an undefined state when an inactive mode of operation is selected,   wherein the communication link carries a signal that has at least three phases.   
     
     
         27 . The processor-readable storage medium of  claim 26 , wherein the voltage states include three valid voltage states, and wherein the virtual signal includes at least one bit that selects between one or more modes of operation of the physical connection. 
     
     
         28 . The processor-readable storage medium of  claim 26 , wherein the communication link includes three physical connections, each physical connection communicating a different phase of the at least three phases when an active mode of operation is selected, and wherein each of the three physical connections is in the high-impedance state in the inactive mode of operation. 
     
     
         29 . The processor-readable storage medium of  claim 26 , wherein:
 the digital signal comprises a first binary bit that selects between a first voltage state and a second voltage state;   the signal that has at least three phases switches within a voltage range bounded by a maximum voltage level and a minimum voltage level;   the first voltage state is defined as the minimum voltage level; and   the voltage level of the second voltage state is selected by the virtual signal as either the maximum voltage level or an intermediate voltage level that is greater than the minimum voltage level and less than the maximum voltage level.   
     
     
         30 . The processor-readable storage medium of  claim 26 , wherein:
 the digital signal comprises a first binary bit that selects between a first voltage state and a second voltage state;   the signal that has at least three phases switches within a voltage range bounded by a maximum voltage level and a minimum voltage level;   the first voltage state is defined as the maximum voltage level; and   the voltage level of the second voltage state is selected by the virtual signal as either the minimum voltage level or an intermediate voltage level that is greater than the minimum voltage level and less than the maximum voltage level.