Apparatus for generating digital thermometer codes

An apparatus comprising:

• a 2-bit bi-directional shift register to generate first and second select signals according to first and second input signals;
• and
• N multiplexers comprising a first multiplexer, a second multiplexer and a third multiplexer coupled to the 2-bit directional shift register, each of the N multiplexers having a first input and a second input, the N multiplexers having cross-coupled outputs operable to form storage units, wherein a first output of the first multiplexer is coupled to the first input of the second multiplexer and to the first input of the third multiplexer, the second multiplexer having a second output coupled to the first input of the first multiplexer, and the third multiplexer having a third output coupled to the second input of the first multiplexer to form a multiplexer chain the N multiplexers together, the N multiplexers to generate a pseudo-thermometer code according to the first and second select signals, wherein the N is an integer greater than two that represents a width of the pseudo-thermometer code, and wherein one of the first and second select signals of the 2-bit bi-directional shift register is provided to a selection of an input of the first and second inputs of said each of the N multiplexers to select one of the first and the second inputs of the N multiplexers in the multiplexer chain;
• and
• wherein the 2-bit bi-directional shift register is operable to generate third and fourth signals to identify a pair of multiplexers, from among the N multiplexers, that are to operate as the storage units.

A system comprising:

• a memory;
• and
• a processor, coupled to the memory, the processor having a input-output (I/O) driver to communicate with another processor, the I/O driver having an impedance controllable by a plurality of transistors, wherein the plurality of transistors to receive a thermometer code generated by a logic comprising:
• a 2-bit bi-directional shift register to generate first and second outputs;
• and
• N multiplexers comprising a first multiplexer, a second multiplexer and a third multiplexer, each of the N multiplexers having a first input and a second input, the N multiplexers having cross-coupled outputs operable to form storage units and coupled together, the first multiplexer having a first output coupled to the first input of the second multiplexer and to the first input of the third multiplexer, the second multiplexer having a second output coupled to the first input of the first multiplexer, and the third multiplexer having a third output coupled to the second input of the first multiplexer to form a multiplexer chain for use in generating the thermometer code, wherein the N is an integer greater than two that represents a width of the thermometer code, and wherein one of the first and second outputs of the 2-bit bidirectional shift register is provided to a selection of an input of the first and second inputs of said each of the N multiplexers to select one of the first and second inputs of the N multiplexers in the multiplexer chain;
• and
• wherein the 2-bit bi-directional shift register is operable to generate third and fourth signals to identify a pair of multiplexers, from among the N multiplexers, that are to operate as the storage units.