Digital data transmission via multi-valued logic signals generated using multiple drive states each causing a different amount of current to flow through a termination resistor

A digital communication system, comprising:

• a first communication device having m data output nodes and a clock output node;
• a second communication device having m data input nodes and a clock input node, wherein each of the m data input nodes corresponds to a different one of the m data output nodes, and wherein the clock input node corresponds to the clock output node;
• m data transmission lines coupled between corresponding data input and output nodes, and a clock transmission line coupled between the clock input node and the clock output node;
• wherein the second communication device comprises an input section including 2m+1 termination resistors, wherein each of m of the termination resistors is coupled between a different one of the m data input nodes and a first power supply voltage level, and wherein each of m of the termination resistors is coupled between a different one of the m data input nodes and a second power supply voltage level, and wherein one of the 2m+1 termination resistors is coupled between the clock input node and the first power supply voltage level;
• wherein an electrical voltage level existing at a given data input node is substantially dependent upon an amount of electrical current flowing through the termination resistor coupled between the given data input node and the first power supply voltage level;
• wherein an electrical voltage level existing at the clock input node is substantially dependent upon an amount of electrical current flowing through the termination resistor coupled between the clock input node and the first power supply voltage level;
• wherein the first communication device comprises an output section coupled to receive n binary data signals and a binary clock signal, and wherein the output section is configured to:
• (i) drive each of the m data output nodes in one of p drive states dependent upon the n binary data signals and in response to the binary clock signal, and wherein n>m and p≧2, and wherein each of the p drive states used to drive a given data output node causes a different amount of electrical current to flow through the termination resistor coupled to the corresponding data input node such that a different electrical voltage level exists at the corresponding data input node in each of the p drive states, and (ii) drive the clock output node in one of q drive states dependent upon the binary clock signal, and wherein q≧1, and wherein each of the q drive states causes a different amount of electrical current to flow through the termination resistor coupled to the clock input node such that a different electrical voltage level exists at the clock input node in each of the q drive states;
• and
• wherein the input section is configured to:
• (i) produce the binary clock signal from the electrical voltage levels existing at the clock input node, and (ii) produce the n binary data signals from the electrical voltage levels existing at the m data input nodes in response to the binary clock signal.

A digital communication system, comprising:

• a first communication device having an output node coupled to a first end of a transmission line and a second communication device having an input node coupled to a second end of the transmission line;
• wherein the first communication device includes an output section coupled to receive binary data and is configured to drive the output node in each of p drive levels, dependent upon the binary data, where p≧3;
• wherein the first communication device is configured to convey a clock signal to said second communication device;
• wherein the second communication device is configured to decode the p drive levels in response to the clock signal thereby reproducing the binary data;
• and wherein the first communication device comprises a plurality of resistors each controlled by a corresponding switch to selectively connect between the output node of the first communication device and a corresponding reference voltage.