Output buffer with programmable voltage swing

An integrated circuit device adapted for optional connection to an external programming circuit, the integrated circuit device comprising:

• at least one circuit, with at least one of the circuits comprising:
• at least one emitter coupled output section having a first output, a second output, and an emitter node;
• at least one current source, each current source being connected in series with the emitter node of a respective emitter coupled output section, each current source having a respective bias voltage input for controlling the amount of current through the respective current source;
• and
• a variable bias generator having an output connected to the bias voltage input of each current source, the variable bias generator being configured to produce a bias voltage at the output of the variable bias generator, the value of the bias voltage produced when there is an external programming circuit connected to the variable bias generator being predictable and useful for controlling the amount of current through each current source, the value of the bias voltage produced when there is no external programming circuit connected to the variable bias generator also being predictable and useful for controlling the amount of current through each current source;
• a buffer circuit interposed between the variable bias circuit and the current source, the buffer circuit having an input connected to the output of the variable bias generator and an output connected to the bias voltage input of the current source;
• and
• an electrical connection area connected to the variable bias generator, the electrical connection area being configured for optional connection of the external programming circuit to the electrical connection area, so that when the external programming circuit is connected to the electrical connection area the bias voltage at the output of the variable bias generator is set to a value other than the default bias voltage to program the magnitude of the voltage swings at the first and second outputs of each emitter coupled output section to a magnitude other than the default magnitude.

A method for programming the magnitude of the output voltage swings of outputs in an integrated circuit device having emitter coupled output transistors and an electrical connection area, the magnitude of the output voltage swings being a function of a reference voltage and of the amount of external resistance connected between the electrical connection area and the reference voltage, the method comprising:

• ascertaining the desired magnitude of the output voltage swings;
• comparing the desired magnitude of the output voltage swings to a default magnitude of the output voltage swings;
• selecting a reference voltage to connect to the external resistance;
• determining the amount of external resistance required to be connected between the electrical connection area and the selected reference voltage to produce the desired magnitude of the output voltage swings;
• and
• connecting the determined external resistance between the electrical connection area and the selected reference voltage to produce the desired magnitude of the output voltage swings.

A method for programming the magnitude of the output voltage swings of outputs in an integrated circuit device having emitter coupled output transistors and an electrical connection area, the magnitude of the output voltage swings being a function of the amount of the external voltage connected between the electrical connection area and a reference voltage, the method comprising:

• ascertaining the desired magnitude of the output voltage swings;
• comparing the desired magnitude of the output voltage swings to a default magnitude of the output voltage swings;
• determining the amount of external voltage required to be connected to the electrical connection area to produce the desired magnitude of the output voltage swings;
• and
• connecting the determined external voltage to the electrical connection area to produce the desired magnitude of the output voltage swings.

An integrated circuit device adapted for optional connection to an external programming circuit, the integrated circuit device comprising:

• at least one emitter coupled output section having a first output, a second output, and an emitter node;
• at least one current source, each current source being connected in series with the emitter node of a respective emitter coupled output section, each current source having a respective bias voltage input for controlling the amount of current through the respective current source;
• a variable bias generator having an output connected to the bias voltage input of each current source, the variable bias generator being configured to produce a bias voltage at the output of the variable bias generator, the value of the bias voltage produced when there is an external programming circuit connected to the variable bias generator being predictable and useful for controlling the amount of current through each current source, the value of the bias voltage produced when there is no external programming circuit connected to the variable bias generator also being predictable and useful for controlling the amount of current through each current source;
• an electrical connection area connected to the variable bias generator, the electrical connection area being configured for optional connection of the external programming circuit to the electrical connection area, so that when the external programming circuit is connected to the electrical connection area the bias voltage at the output of the variable bias generator is set to a value other than the default bias voltage to program the magnitude of the voltage swings at the first and second outputs of each emitter coupled output section to a magnitude other than the default magnitude;
• and
• wherein the variable bias generator comprises:
• a variable bias generator first resistor having a first end connected to a first voltage and a second end connected to the electrical connection area;
• a variable bias generator second resistor having a first end and a second end, the first end of the variable bias generator second resistor being connected to the electrical connection area;
• a variable bias generator third resistor having a first end and a second end, the first end of the variable bias generator third resistor being connected to the second end of the variable bias generator second resistor, the second end of the variable bias generator third resistor being connected to a second voltage;
• a variable bias generator first transistor having a collector, a base, and an emitter, the collector of the variable bias generator first transistor being connected to the electrical connection area, the base of the variable bias generator first transistor being connected to the second end of the variable bias generator second resistor and the first end of the variable bias generator third resistor, the emitter of the variable bias generator first transistor being connected to the second reference voltage, and wherein the output of the variable bias generator is connected to the electrical connection area;
• and
• a variable bias generator capacitor having a first end connected to the electrical connection area, and a second end connected to the second reference voltage.

An integrated circuit device adapted for optional connection to an external programming circuit, the integrated circuit device comprising:

• at least one circuit, with at least one of the circuits comprising:
• at least one emitter coupled output section having a first output, a second output, and an emitter node;
• at least one current source, each current source being connected in series with the emitter node of a respective emitter coupled output section, each current source having a respective bias voltage input for controlling the amount of current through the respective current source;
• and
• a variable bias generator having an output connected to the bias voltage input of each current source, the variable bias generator being configured to produce a bias voltage at the output of the variable bias generator, the value of the bias voltage produced when there is an external programming circuit connected to the variable bias generator being predictable and useful for controlling the amount of current through each current source, the value of the bias voltage produced when there is no external programming circuit connected to the variable bias generator also being predictable and useful for controlling the amount of current through each current source;
• an electrical connection area connected to the variable bias generator, the electrical connection area being configured for optional connection of the external programming circuit to the electrical connection area, so that when the external programming circuit is connected to the electrical connection area the bias voltage at the output of the variable bias generator is set to a value other than the default bias voltage to program the magnitude of the voltage swings at the first and second outputs of each emitter coupled output section to a magnitude other than the default magnitude;
• and
• wherein the variable bias generator comprises:
• a variable bias generator first resistor having a first end connected to a first voltage and a second end connected to the electrical connection area;
• a variable bias generator second resistor having a first end and a second end, the first end of the variable bias generator second resistor being connected to the electrical connection area;
• a variable bias generator third resistor having a first end and a second end, the first end of the variable bias generator third resistor being connected to the second end of the variable bias generator second resistor, the second end of the variable bias generator third resistor being connected to a second voltage;
• a variable bias generator first transistor having a collector, a base, and an emitter, the collector of the variable bias generator first transistor being connected to the electrical connection area, the base of the variable bias generator first transistor being connected to the second end of the variable bias generator second resistor and the first end of the variable bias generator third resistor, the emitter of the variable bias generator first transistor being connected to the second voltage, and wherein the output of the variable bias generator is connected to the electrical connection area;
• and
• a variable bias generator capacitor having a first end connected to the electrical connection area, and a second end connected to the second reference voltage.