Proportional to absolute temperature (ptat) voltage generating circuit for generating a ptat voltage and acts as a temperature sensor

A proportional to-absolute-temperature (PTAT) voltage generating circuit connected between a power supply voltage source and a ground for providing a PTAT voltage at an output terminal of the PTAT voltage generating circuit to act as a temperature sensor, comprising:

• a first P-channel metal oxide semiconductor (PMOS) transistor (M4) that comprises a gate terminal, a source terminal, and a drain terminal, wherein the gate terminal of the first PMOS transistor (M4) is connected to a collector of a second PNP transistor (T2),
• wherein the second PNP transistor (T2) generates a first PTAT voltage by determining a difference between a base-emitter voltage of a first PNP transistor (T1) and the second PNP transistor (T2), wherein an emitter of the first PNP transistor (T1) is connected to a first input terminal of a differential amplifier, and an emitter of the second PNP transistor (T2) is connected to a second input terminal of the differential amplifier,
• wherein the first PTAT voltage is amplified by multiplying by a factor that is equal to a ratio of a first equivalent resistance (R2) and a second resistance (R1) of the first PMOS transistor (M4) to generate a second PTAT voltage,
• wherein the first equivalent resistance (R2) is obtained from a series combination of a second PMOS transistor (M5), a third PMOS transistor (M6), a fourth PMOS transistor (M7), a fifth PMOS transistor (M8), a sixth PMOS transistor (M9), and a seventh PMOS transistor (M10), wherein the second PTAT voltage is temperature invariant and thereby, the PTAT voltage generating circuit act as the temperature sensor.