초록 ▼

Circuits and methods for generating a temperature dependent signal are described involving: generating a thermal voltage referenced positive temperature coefficient signal using a pair of transistors operating at different current densities; generating a transistor voltage referenced negative temper

Circuits and methods for generating a temperature dependent signal are described involving: generating a thermal voltage referenced positive temperature coefficient signal using a pair of transistors operating at different current densities; generating a transistor voltage referenced negative temperature coefficient signal using a transistor voltage of one of said pair of transistors; and subtracting one of said positive and negative temperature coefficient signals from the other of said signals to generate said temperature dependent signal, whereby the temperature dependence of said temperature dependent signal is greater than either of said subtracted signals.

대표청구항 ▼

1. A temperature sensor comprising:a current mirror with an input and at least two outputs;a first reference current generator having a first current input and a first current output and configured to generate a first reference current with a positive temperature coefficient at said first current ou

1. A temperature sensor comprising:a current mirror with an input and at least two outputs;a first reference current generator having a first current input and a first current output and configured to generate a first reference current with a positive temperature coefficient at said first current output in response to said first current input;a second reference current generator having a second current input and a second current output and configured to generate a second reference current with a negative temperature coefficient at said second current output in response to said second current input; and whereinone of said first and second reference generators has a respective current output coupled to said input of said current mirror;said first current input of said first reference generator and said second current input of said second reference generator share an input node coupled to a first of said current mirror outputs; andthe other of said first and second reference generators has a respective current output coupled to a second of said current mirror outputs to thereby provide a current sense node; and whereinsaid first reference current generator comprises a thermal voltage referenced current source; andsaid second reference current generator comprises a temperature dependent semiconductor characteristic referenced current source. 2. A temperature sensor according to claim 1, wherein said first reference current generator comprises first and second transistors configured to operate at different current densities, said first transistor being coupled to said first current input and said second transistor being coupled to said first current output. 3. A temperature sensor as claimed in claim 2 wherein said second reference current generator comprises a transistor characteristic referenced current source. 4. A temperature sensor as claimed in claim 3 wherein said transistor characteristic to which said second current source is referenced comprises a characteristic of one of said first and second transistors of said first reference current generator. 5. A temperature sensor as claimed in claim 2 wherein said first and second transistors comprise MOS transistors. 6. A temperature sensor as claimed in claim 2 wherein said first and second transistors comprise bipolar transistors. 7. A temperature sensor as claimed in claim 1 wherein said temperature dependent semiconductor characteristic comprises a diode junction characteristic. 8. A temperature sensor as claimed in claim 7 wherein said second reference current generator comprises a bipolar transistor base-emitter voltage referenced current source. 9. A temperature sensor as claimed in claim 1, wherein said first reference current generator comprises first and second transistors configured to operate at different current densities, said first transistor being coupled to said first current input and said second transistor being coupled to said first current output; wherein said temperature dependent semiconductor characteristic comprises a diode junction characteristic; wherein said second reference current generator comprises a bipolar transistor base-emitter referenced current source; and wherein said base-emitter voltage reference of said base-emitter voltage referenced current source comprises a base-emitter voltage of said first transmitter. 10. A temperature sensor as claimed in claim 1 wherein said first and second reference current generators share a pair of series connected transistors coupled to said input node for generating both said first and second reference currents. 11. A temperature sensor as claimed in claim 1, fabricated in MOS technology. 12. A temperature sensor as claimed in claim 6, fabricated in CMOS technology, wherein said bipolar transistors comprise parasitic devices. 13. A temperature sensor as claimed in claim 8, fabricated in CMOS technology, wherein said bipolar transistors comprise parasitic devices. 14. A temperature sensor as claimed in clai m 1 wherein said first reference current generator has said first current output coupled to said input of said current mirror. 15. A temperature sensor as claimed in claim 1, further comprising a temperature adjust circuit configured to alter current through said sense node to thereby alter a sensed temperature. 16. A temperature sensor as claimed in claim 1, further comprising a positive feedback circuit configured to inject current into said shared input node. 17. A temperature sensor as claimed in claim 16, wherein said positive feedback circuit comprises an output transistor coupled to said current sense node and a feedback transistor coupled to said shared input node, said output transistor and said feedback transistor being coupled to a common current source and configured such that as the current in one of said output and said feedback transistor increases the current in the other decreases. 18. A temperature sensor as claimed in claim 16, further comprising an output circuit coupled to said sense node to provide an output which switches at a threshold temperature, wherein said feedback circuit is configured to provide hysteresis for said switching. 19. A method of providing a temperature dependent signal, the method using:a current mirror with an input and at least two outputs;a first reference current generator having a first current input and a first current output;a second reference current generator having a second current input and a second current output; and whereinone of said first and second reference generators has a respective current output coupled to said input of said current mirror;said first current input of said first reference generator and said second current input of said second reference generator share an input node coupled to a first of said current mirror outputs; andthe other of said first and second reference generators has a respective current output coupled to a second of said current mirror outputs to thereby provide a current sense node;the method comprising:generating, using said first current generator, a first, transistor thermal voltage referenced current with a positive temperature coefficient at said first current output in response to a signal from said current mirror at said shared input node;generating, using said second current generator, a second transistor voltage referenced current with a negative temperature coefficient at said second current output in response to said signal from said current mirror at said shared input node; andcombining signals dependent upon said first and second reference currents at said sense node to provide said temperature dependent signal. 20. A method as claimed in claim 19 wherein said first transistor thermal voltage referenced current is a bipolar transistor thermal voltage referenced current, and wherein said second transistor voltage referenced is a bipolar transistor base-emitter voltage referenced current. 21. A method as claimed in claim 19 wherein said first transistor thermal voltage referenced current is a MOS transistor thermal voltage referenced current, and wherein said second transistor voltage referenced current is a MOS threshold or gate-source voltage referenced current. 22. A temperature detection circuit comprising:a current mirror having an input and first and second mirrored current outputs, said input and said first mirrored output being coupled via respective first and second MOS transistors channels to respective first and second MOS transistors to set a ratio of current densities in said first and second transistors to provide a positive temperature coefficient current from said second mirrored current output;a third MOS transistor having a gate connection coupled to a gate connection of said first MOS transistor and a pair of channel connections, one of said channel connections being coupled via a resistor to a common connection of said first and second transistors to provide a negative temperature coefficient current out put at said other channel connection whereby said current output is referenced to a temperature-dependent voltage of said first transistor, said other channel connection being coupled to said second mirrored current output to provide a temperature dependent output. 23. A temperature detection circuit as claimed in claim 22 wherein said first and second transistors comprise bipolar transistors, and wherein said temperature-dependent voltage of said first transistor comprises a base-emitter voltage of said first transistor. 24. A temperature detection circuit as claimed in claim 23, further comprising a feedback circuit to provide positive feedback to cause said temperature dependent output to exhibit bistable behavior with hysteresis. 25. A temperature detection circuit as claimed in claim 24, wherein said feedback circuit is configured effectively to adjust the ratio of said current mirror for said first mirrored output. 26. A temperature detection circuit as claimed in claim 22, further comprising a temperature adjuster effectively to adjust said negative temperature coefficient current output a said other channel connection. 27. A temperature detection circuit as claimed in claim 22, fabricated in CMOS technology, wherein said bipolar transistors comprise inherent parasitic transistors. 28. A temperature detection circuit comprising:a current mirror having an input and first and second mirrored current outputs, said second and first mirrored outputs being coupled via respective first and second MOS transistor channels to respective first and second MOS transistors;a third MOS transistor having a gate connection coupled to a gate connection of said first MOS transistor and a pair of channel connections, one of said channel connections begin coupled via a resistor to a common connection of said first and second transistors to provide a negative temperature coefficient current output at said other channel connection whereby said current output is referenced to a temperature-dependent voltage of said first transistor, said other channel connection being coupled to said current mirror input to provide negative temperature coefficient current from said second mirrored current output; and whereina ratio of current densities in said first and second transistors determines a positive temperature coefficient current which is combined with said current from said second mirrored current output to provide a temperature dependent output. 29. A temperature detection circuit as claimed in claim 28 wherein said first and second transistors comprise bipolar transistors, and wherein said temperature-dependent voltage of said first transistor comprises a base-emitter voltage of said first transistors. 30. A temperature detection circuit as claimed in claim 29, further comprising a feedback circuit to provide positive feedback to cause said temperature dependent output to exhibit bistable behaviour with hysteresis. 31. A temperature detection circuit as claimed in claim 30, wherein said feedback circuit is configured effectively to adjust the ratio of said current mirror for said first mirrored output. 32. A temperature detection circuit as claimed in claim 28, further comprising a temperature adjuster effectively to adjust said negative temperature coefficient current output at said other channel connection. 33. A temperature detection circuit as claimed in claim 28, fabricated in CMOS technology, wherein said bipolar transistors comprise inherent parasitic transistors. 34. A method of generating a temperature dependent signal, the method comprising:generating a thermal voltage referenced positive temperature coefficient signal using a pair of transistors operating at different current densities;generating a transistor voltage referenced negative temperature coefficient signal, a temperature variation of said negative temperature coefficient signal being dependent upon a temperature variation of a transistor voltage of one of said pair of trans istors; andsubtracting one of said positive and negative temperature coefficient signals from the other of said signals to generate said temperature dependent signal, whereby the temperature dependence of said temperature dependent signal is greater than either of said subtracted signals. 35. A method as claimed in claim 34 wherein said pair of transistors comprises a pair of bipolar transistors and wherein said transistor voltage comprises a base-emitter voltage. 36. A method as claimed in claim 34, wherein said positive and negative temperature coefficient signals comprise current signals. 37. A method as claimed in claim 36, wherein said subtracting comprises applying said positive and negative temperature coefficient signals to a detection node. 38. A method as claimed in claim 34, further comprising applying positive feedback to the transistor of said pair also used for generating said negative temperature coefficient signal. 39. A method as claimed in claim 34, further comprising adjusting said temperature dependent signal by adjusting said negative temperature coefficient signal. 40. A method as claimed in claim 34 wherein said pair of transistors is configured such that four terminals of the transistors, two of each transistor of the pair, are connected together. 41. A circuit for generating a temperature dependent signal the circuit comprising:means for generating a thermal voltage referenced positive temperature coefficient signal using a pair of transistors operating at different current densities;means for generating a transistor voltage referenced negative temperature coefficient signal, a temperature variation of said negative temperature coefficient signal being dependent upon a temperature variation of a transistor voltage of one of said pair of transistors; andmeans for subtracting one of said positive and negative coefficient signals from the other of said signals to generate said temperature dependent signal, whereby the temperature dependence of said temperature dependent signal is greater than either of said subtracted signals. 42. A circuit as claimed in claim 41 wherein said transistors comprise bipolar transistors, and wherein said transistor voltage comprises a base-emitter voltage. 43. A circuit as claimed in claim 41 wherein said transistors comprise MOS transistors, and wherein said transistor voltage comprises a MOS transistor threshold or gate-source voltage. 44. A circuit as claimed in claim 41 wherein said pair of transistors is configured such that four terminals of the transistors, two of each transistor of the pair, are connected together. 45. A circuit as claimed in claim 41 further comprising a positive feedback circuit configured to inject current into a common input node of said positive and negative temperature coefficient signal generation means.