Patent ID: 6091286
Filing Date: 2000-07-18
Classification: G05F

Abstract:
A circuit for producing an output reference current having an arbitrary predetermined temperature dependence, comprising:a first field effect transistor (FET) having a gate, a source, and a drain;a second field effect transistor having a gate, a source, and a drain,said first FET source and said second FET source being commonly connected,said first FET having a threshold voltage,a bias source, operably coupled to the drain, gate and source of the second FET, that forces the voltage between the gate and the source of the second FET to be substantially equal to the threshold voltage of the first FET; anda temperature dependent current source that provides a temperature dependent current through a first resistor to produce a temperature dependent voltage;the gate of the first FET being operably coupled to the gate of the second FET through the first resistor so that the voltage between the gate and the source of the first FET is equal to a sum of the second FET's gate to source voltage plus the temperature dependent voltage, and producing the output reference current at the drain of the first FET,a second resistor coupled between the first resistor and the sources of the first and second FETs,said temperature dependent current source including:a first current source which is substantially independent of temperature variation and has a first current value determined by a first scaling factor of arbitrary value, anda second current source which is substantially proportional to absolute temperature and has a second current value determined by a second scaling factor of arbitrary value.