Abstract: A PTAT current source comprising a first branch including a bipolar transistor structure connected in diode configuration, and first and second sub-branches coupled to the bipolar transistor structure, the first sub-branch including a p-channel MOSFET transistor connected in diode configuration and an n-channel MOSFET transistor which is not connected in diode configuration, and the second sub-branch including a p-channel MOSFET transistor not connected in diode configuration and an n-channel MOSFET transistor connected in diode configuration; and a second branch including a bipolar transistor structure connected in diode configuration, and third and fourth sub-branches coupled to the bipolar transistor structure, the third sub-branch including a p-channel MOSFET transistor connected in diode configuration and an n-channel MOSFET transistor which is not connected in diode configuration, and the fourth sub-branch including a p-channel MOSFET transistor not connected in diode configuration and an n-channel MOSF