Reference circuit that provides a temperature dependent voltage
A reference circuit that includes a first circuit configured to provide a temperature dependent current, a second circuit configured to provide a first current, and a third circuit. The third circuit is configured to provide a temperature dependent voltage based on the first current and the temperature dependent current. The temperature dependent voltage has a voltage versus temperature slope established by the third circuit and a voltage level established by the first current.
1 . A reference circuit comprising:
a first circuit configured to provide a temperature dependent current;
a second circuit configured to provide a first current; and
a third circuit configured to provide a temperature dependent voltage based on the first current and the temperature dependent current, wherein the temperature dependent voltage has a voltage versus temperature slope established by the third circuit and a voltage level established by the first current.
2 . The reference circuit of claim 1 , wherein the second circuit provides a second current that comprises the first current and the temperature dependent current and the third circuit is configured to provide a third current that mirrors the second current.
3 . The reference circuit of claim 1 , wherein the third circuit includes a resistive element configured to receive a current that mirrors the first current and the temperature dependent current and to establish the voltage versus temperature slope of the temperature dependent voltage.
4 . The reference circuit of claim 1 , wherein the first circuit comprises:
a first resistive element; and
a diode coupled to the first resistive element, wherein the diode has a diode voltage that is dependent on temperature and a constant voltage is applied across the first resistive element and the diode to provide the temperature dependent current.
5 . The reference circuit of claim 4 , wherein the second circuit includes a second resistive element coupled across the first resistive element and the diode and configured to provide the first current.
6 . The reference circuit of claim 1 , wherein the first circuit comprises:
a bandgap reference circuit; and
a current mirror coupled to the bandgap reference to provide the temperature dependent current.
7 . An electronic system comprising:
a random access memory that includes a reference circuit configured to provide a temperature dependent reference voltage, wherein the reference circuit comprises:
a temperature dependent current source configured to provide a temperature dependent current;
a constant current source configured to provide a constant current; and
a circuit configured to mirror the constant current and the temperature dependent current and provide the temperature dependent reference voltage based on the mirrored constant current and temperature dependent current, wherein the circuit is configured to provide a voltage level of the temperature dependent reference voltage based on the constant current and to establish a voltage versus temperature slope of the temperature dependent reference voltage.
8 . The electronic system of claim 7 , wherein the random access memory includes a regulator configured to receive the temperature dependent reference voltage and provide a temperature dependent output voltage based on the temperature dependent reference voltage.
9 . The electronic system of claim 8 , wherein the random access memory includes a temperature dependent delay chain configured to receive the temperature dependent output voltage and provide a substantially constant delay versus temperature.
10 . The electronic system of claim 7 , wherein the circuit comprises:
a differential amplifier configured to receive a first constant voltage; and
a first transistor configured to be controlled by the differential amplifier to provide a second constant voltage and to provide a first current comprising the temperature dependent current and the constant current.
11 . The electronic system of claim 10 , wherein the circuit comprises:
a second transistor configured to be controlled by the differential amplifier and to provide a second current that mirrors the first current; and
a resistive element configured to receive the second current to provide the temperature dependent reference voltage and the voltage versus temperature slope of the temperature dependent reference voltage.
12 . A reference circuit comprising:
a temperature dependent current source configured to provide a temperature dependent current;
a constant current source configured to provide a constant current;
a differential amplifier configured to receive a first constant voltage and provide an output voltage;
a first transistor configured to receive the output voltage to provide a second constant voltage and to provide a first current comprising the temperature dependent current and the constant current;
a second transistor configured to receive the output voltage to provide a second current that mirrors the first current; and
a first resistive element configured to receive the second current to provide a temperature dependent voltage and a voltage versus temperature slope of the temperature dependent voltage, wherein a voltage level of the temperature dependent voltage is based on the constant current.
13 . The reference circuit of claim 12 , wherein the constant current source comprises a resistive element configured to receive the second constant voltage to provide the constant current.
14 . The reference circuit of claim 12 , wherein the temperature dependent current source comprises:
a resistive element; and
a diode coupled to the resistive element.
15 . The reference circuit of claim 12 , wherein the temperature dependent current source comprises:
a bandgap reference circuit; and
a current mirror coupled to the bandgap reference.
16 . A random access memory comprising:
means for providing a temperature dependent current;
means for providing a current to establish a voltage level of a temperature dependent voltage;
means for mirroring the current and the temperature dependent current to provide the temperature dependent voltage; and
means for establishing a voltage versus temperature slope of the temperature dependent voltage.
17 . The random access memory of claim 16 , wherein the means for providing a temperature dependent current comprises:
means for applying a constant voltage across a resistor and a diode.
18 . The random access memory of claim 16 , wherein the means for providing a temperature dependent current comprises:
means for mirroring a bandgap reference temperature dependent current.
19 . The random access memory of claim 16 , comprising:
means for regulating a temperature dependent output voltage based on the temperature dependent voltage.
20 . A method for providing a temperature dependent voltage comprising:
providing a temperature dependent current;
providing a current;
mirroring the current and the temperature dependent current to provide the temperature dependent voltage;
establishing a voltage versus temperature slope of the temperature dependent voltage; and
establishing a voltage level of the temperature dependent voltage.
21 . The method of claim 20 , wherein providing a temperature dependent current comprises:
applying a constant voltage across a resistor and a diode.
22 . The method of claim 20 , wherein providing a temperature dependent current comprises:
mirroring a bandgap reference temperature dependent current.
23 . The method of claim 20 , wherein providing a current comprises:
applying a constant voltage across a resistor.
24 . The method of claim 20 , comprising:
regulating a temperature dependent output voltage based on the temperature dependent voltage.
25 . A method for providing a temperature dependent output voltage in a random access memory, comprising:
receiving a temperature dependent current;
receiving a constant current;
combining the temperature dependent current and the constant current;
mirroring the combined current;
receiving the mirrored current at a resistor to provide a voltage level of a temperature dependent reference voltage based on the constant current and to establish a voltage versus temperature slope of the temperature dependent reference voltage.
26 . The method of claim 25 , comprising:
receiving the temperature dependent reference voltage; and
regulating a temperature dependent output voltage based on the temperature dependent reference voltage.
27 . The method of claim 25 , comprising:
receiving a first constant voltage at a differential amplifier; and
controlling a first transistor via the differential amplifier to provide a second constant voltage and the combined current.
28 . The method of claim 27 , wherein mirroring the combined current comprises controlling a second transistor via the differential amplifier to provide a second current that mirrors the combined current.
29 . A method for providing a temperature dependent voltage comprising:
receiving a temperature dependent current;
receiving a constant current;
receiving a first constant voltage at a differential amplifier to provide an output voltage;
receiving the output voltage at a first transistor to provide a second constant voltage and a first current comprising the temperature dependent current and the constant current;
receiving the output voltage at a second transistor to provide a second current that mirrors the first current; and
receiving the second current at a first resistive element to provide a temperature dependent voltage and a voltage versus temperature slope of the temperature dependent voltage and to establish a voltage level of the temperature dependent voltage based on the constant current.
30 . The method of claim 29 , comprising:
receiving the second constant voltage at a second resistive element to provide the constant current.
31 . The method of claim 29 , comprising:
receiving the second constant voltage across a third resistive element and a diode coupled to the third resistive element to provide the temperature dependent current.
32 . The method of claim 29 , comprising:
providing the temperature dependent current via a current mirror coupled to a bandgap reference.