Programmable reference voltage generating circuit

A reference voltage generating circuit comprising:

• a binary-to-thermometer for converting binary codes into thermometer codes, wherein the binary-to-thermometer comprises thermometer code generators for generating the thermometer codes in response to the binary codes, wherein the thermometer code generators each include:
• a logic gate for selectively receiving the binary codes;
• transmission gates for transmitting an output of the logic gate to generate a thermometer code in response to a selected signal of the binary codes;
• and transistors for resetting the thermometer code in response to the selected signal of the binary codes;
• an internal reference voltage generator for generating an internal reference voltage in response to the thermometer codes from the binary-to-thermometer, wherein the internal reference voltage generator changes a level of the internal reference voltage in response to the thermometer codes;
• a selector for selecting the internal reference voltage or an external reference voltage in response to a reference voltage select signal;
• and
• a voltage regulator for regulating a reference voltage selected by the selector.

A reference voltage generating circuit comprising:

• a binary-to-thermometer for converting binary codes into thermometer codes;
• an internal reference voltage generator for generating an internal reference voltage on an internal reference voltage node in response to the thermometer codes from the binary-to-thermometer, wherein the internal reference voltage generator charges a level of the internal reference voltage in response to the thermometer codes;
• and
• a selector for selecting the internal reference voltage or an external reference voltage in response to a reference voltage select signal,
• wherein the internal reference voltage generator comprises:
• a reference voltage bias part having a diode type first transistor connected between a power source voltage node and the internal reference voltage node and a diode type second transistor connected between the internal reference voltage node and a ground voltage node;
• a reference voltage coding part for increasing or decreasing the internal reference voltage in response to the thermometer codes;
• voltage-up controllers connected between the power source voltage node and the internal reference voltage node, for increasing the internal reference voltage in response to the thermometer codes;
• voltage-down controllers connected between the internal reference voltage node and the internal reference voltage node, for increasing the internal reference voltage in response to the thermometer codes;
• wherein the voltage-up controllers each comprise:
• an inverter connected between the power source voltage node and the internal reference voltage node and controlled by the codes;
• and
• a transistor connected between the power source voltage node and the internal reference voltage node, for increasing the internal reference voltage in response to outputs of the inverter.