Non-linearity compensation circuit and bandgap reference circuit using the same
AssigneeFaraday Technology Corp.
InventorsKuen-Shan Chang, Uei-Shan Uang
Life of this patent
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Abstract
A non-linearity compensation circuit and a bandgap reference circuit using the same for compensating non-linear effects of a reference voltage are provided. In the non-linearity compensation circuit, the reference voltage is transformed into a temperature independent current. A current mirror mirrors the temperature independent current for biasing a bipolar junction transistor (BJT). Further, two resistors are used for estimating a non-linear voltage, so as to compensate the reference voltage.
Claims27
A bandgap reference circuit, comprising:
- a PTAT current unit, generating a PTAT current and summing a non-linear current;
- a first transistor, biased by the PTAT current output from the PTAT current unit;
- a second transistor, biased by the PTAT current output from the PTAT current unit;
- an amplifier and voltage divider circuit, for outputting a reference voltage in response to a base-emitter voltage, a PTAT voltage, and a non-linear voltage;
- and
- a non-linearity compensation circuit, for converting the reference voltage as a temperature independent bias current, wherein the non-linearity compensation circuit comprises:
- a third transistor, biased by the temperature independent current;
- a first resistor, coupled to the first transistor and the third transistor, wherein the voltage drop across the first resistor is the non-linear voltage;
- and
- a second resistor, coupled to the third transistor, wherein the voltage drop across the second resistor is the non-linear voltage;
- wherein the non-linear effect and the temperature dependent effect of the reference voltage are compensated by the non-linearity compensation circuit.
A bandgap reference circuit, comprising:
- a PTAT current unit, generating a PTAT current and summing a non-linear current;
- a first transistor, biased by the PTAT current output from the PTAT current unit;
- a second transistor, biased by the PTAT current output from the PTAT current unit;
- a first resistor, coupled to the PTAT current mirror, wherein the PTAT current and the non-linear current output from the PTAT current mirror flow through the first resistor, such that the voltage drop across the first resistor is a PTAT voltage and a non-linear voltage;
- a third transistor, coupled to the first resistor, wherein a base-emitter voltage of the third transistor is a negative temperature coefficient voltage, and a reference voltage is output from a node between the first resistor and the PTAT current mirror;
- and
- a non-linearity compensation circuit, converting the reference voltage into a temperature independent current, wherein the non-linearity compensation circuit comprises:
- a fourth transistor, biased by the temperature independent current;
- a second resistor, coupled to the first transistor and the fourth transistor, wherein the voltage drop across the second resistor is the non-linear voltage;
- and
- a third resistor, coupled to the fourth transistor, wherein the voltage drop across the third resistor is the non-linear voltage;
- wherein the non-linear effect and the temperature dependent effect of the reference voltage are compensated by the non-linearity compensation circuit.
A non-linearity compensation circuit, for compensating the non-linear effect and the temperature dependent effect of a reference voltage generated by a bandgap reference circuit, the bandgap reference circuit having a first transistor and a second transistor both biased by a PTAT current, and a first resistor, comprising:
- an operation amplifier, for receiving the reference voltage;
- a third transistor, coupled to the operation amplifier, wherein the operation amplifier and the third transistor convert the reference voltage into a temperature independent current;
- a temperature independent current mirror, coupled to the third transistor, for mirroring the temperature independent current;
- a fourth transistor, for receiving the temperature independent current generated by the temperature independent current mirror, biased by the temperature independent current;
- a second resistor, coupled to the first transistor and the fourth transistor, a non-linear voltage being across the second resistor;
- and
- a third resistor, coupled to the first resistor and the fourth transistor, the non-linear voltage being across the third resistor.
Dependencies are inferred from the claim text.