Symmetrical positive and negative reference voltage generation
In an embodiment, an electronic device includes a first amplifier having a non-inverting input configured to receive a reference voltage and an inverting input coupled to a first output node, where the first amplifier is configured to produce a first output voltage at the first output node. The electronic device also includes a second amplifier having a non-inverting input coupled to a ground reference level, and an inverting input coupled to the first output node via a first resistor and to a second output node via a second resistor, where the second amplifier is configured to produce a second output voltage at the second output node.
1. An electronic device, comprising:
a first amplifier having a non-inverting input configured to receive a reference voltage and an inverting input coupled to a first output node, wherein the first amplifier is configured to produce a first output voltage at the first output node;
a second amplifier having a non-inverting input coupled to a ground reference level, and an inverting input coupled to the first output node via a first resistor and to a second output node via a second resistor, wherein the second amplifier is configured to produce a second output voltage at the second output node, wherein the reference voltage is selected via a multiplexer coupled to a resistor ladder, and wherein the resistor ladder is coupled to a reference current source or to a reference voltage source; and
a low-pass filter coupled to the multiplexer and to the non-inverting input of the first amplifier.
2. The electronic device of claim 1 , wherein the first amplifier has a first stage configured to output a maximum current at an intermediary node.
3. An electronic device, comprising:
a first amplifier having a non-inverting input configured to receive a reference voltage and an inverting input coupled to a first output node, wherein the first amplifier is configured to produce a first output voltage at the first output node;
a second amplifier having a non-inverting input coupled to a ground reference level, and an inverting input coupled to the first output node via a first resistor and to a second output node via a second resistor, wherein the second amplifier is configured to produce a second output voltage at the second output node,
wherein the first amplifier has a first stage configured to output a maximum current at an intermediary node, and wherein the first amplifier further includes a capacitor coupled to the intermediary node and to the ground reference level.
4. The electronic device of claim 3 , further comprising a buffer stage coupled to the intermediary node.
5. The electronic device of claim 3 , wherein in response to a positive step change in the reference voltage, the first output voltage increases at a first rate given by a ratio between the maximum current and a capacitance presented by the capacitor.
6. The electronic device of claim 5 , wherein the second output voltage decreases with a second rate having a magnitude equal to the first rate.
7. A dual-reference voltage source, comprising:
a first amplifier configured to produce a first reference voltage at a first output node with a first slew rate;
a second amplifier coupled to the first output node and configured to produce a second reference voltage at a second output node with a second slew rate having a magnitude equal to the first slew rate, wherein the second reference voltage is symmetric with respect to the first reference voltage, wherein the first amplifier has a non-inverting input configured to receive a selected voltage and an inverting input coupled to the first output node, wherein the selected voltage is selected via a multiplexer coupled to a resistor ladder, and wherein the resistor ladder is coupled to a reference current source or to a reference voltage source; and
a low-pass filter coupled to the multiplexer and to the non-inverting input of the first amplifier.
8. The dual-reference voltage source of claim 7 , wherein the second amplifier has a non-inverting input coupled to a ground reference level, and an inverting input coupled to the first output node via a first resistor and to the second output node via a second resistor.
9. The dual-reference voltage source of claim 7 , wherein the first amplifier has a first stage configured to output a maximum output current at an intermediary node.
10. A dual-reference voltage source, comprising:
a first amplifier configured to produce a first reference voltage at a first output node with a first slew rate;
a second amplifier coupled to the first output node and configured to produce a second reference voltage at a second output node with a second slew rate having a magnitude equal to the first slew rate, wherein the second reference voltage is symmetric with respect to the first reference voltage, wherein the first amplifier has a non-inverting input configured to receive a selected voltage and an inverting input coupled to the first output node, wherein the first amplifier has a first stage configured to output a maximum output current at an intermediary node, and wherein the first amplifier further includes a capacitor coupled to the intermediary node and to the ground reference level.
11. The dual-reference voltage source of claim 10 , wherein, in response to a change in the selected voltage, the first reference voltage changes with the first slew rate given by a ratio between the maximum output current and a capacitance of the capacitor.
12. The dual-reference voltage source of claim 11 , wherein the second reference voltage changes in the opposite direction with a second slew rate having a magnitude equal to the first slew rate.
13. A method, comprising:
receiving, at a non-inverting input of a first amplifier, a reference voltage, wherein the first amplifier has an inverting input coupled to a first output node;
producing a first output voltage at the first output node; and
producing a second output voltage symmetric with respect to the first output voltage at a second output node of a second amplifier, wherein the second amplifier has a non-inverting input coupled to a ground reference level, and an inverting input coupled to the first output node via a first resistor and to the second output node via a second resistor,
wherein the first amplifier has a first stage configured to output a maximum output current at an intermediary node, wherein the first amplifier further includes a capacitor coupled to the intermediary node and to the ground reference level, and wherein in response to a change in the selected voltage, the first reference voltage increases with a slew rate given by a ratio between the maximum output current and a capacitance of the capacitor.
14. The method of claim 13 , wherein the first resistor has a first resistance and the second resistor has a second resistance, and wherein a ratio between the first and second resistances is proportional to a ratio between the magnitudes of the first and second output voltages.