Low power CMOS reference generator with low impedance driver

Claim 2

A low power, low output impedance on-chip voltage reference with high current drive capability for accepting a VREFOUT signal where the magnitude of V REFOUT output is about equal to the magnitude of V REFIN ' said low output impedance voltage reference comprising: a preamplifier, including a first plurality of interconnected transistors, having an input terminal coupled to the output terminal of the high output impedance voltage reference, with said preamplifier for preventing a substantial amount of current from flowing into or out of the output terminal of said high output impedance voltage reference and for providing first and second preamplifier output signals at first and second preamplifier output terminals, respectively; a source follower output stage, including a second plurality of interconnected transistors, having first and second inputs coupled to said first and second preamplifier outputs, respectively, and for providing the V REFOUT signal at an output stage output terminal and for providing a high source/sink current driving capability and low output impedance; and means for biasing the transistors in said first and second plurality in the subthreshold region to minimise power dissipation.

Claim 3

A low power, low output impedance on-chip voltage reference with high current drive capability for accepting a VREFIN signal from the output terminal of a high output impedance voltage reference and for providing a V REFOUT signal where the magnitude of V REFOUT is about equal to the magnitude of V REFIN I said low output impedance voltage reference comprising: a preamplifier, including a first plurality of interconnected transistors, having an input terminal coupled to the output terminal of the high output impedance voltage reference, with said preamplifier for preventing a substantial amount of current from flowing into or out of the output terminal of said high output impedance voltage reference and for providing first and second preamplifier output signals at first and second preamplifier output terminals, respectively; an isolation stage, including a second plurality of interconnected transistors, having first and second inputs coupled to said first and second preamplifier outputs and first and second output terminals, said isolation stage for isolating said preamplifier from the effects of an output voltage bounce and for increasing the current driving capability of the voltage reference; a source follower output stage, including a third plurality of interconnected transistors, having first and second inputs coupled to said first and second isolation stage outputs, respectively, and for providing the V REFOUT signal at an output stage output terminal and for providing a high source/sink current driving capability and low output impedance; and means for biasing the transistors in said first, second and third pluralities in the subthreshold region to minimise power dissipation.

Claim 4

A low power, low output impedance on-chip voltage reference with high current drive capability for accepting a VREFIN signal from the output terminal of a high output impedance voltage reference and for providing a V REFOUT signal where the magnitude of V REFOUT is about equal to the magnitude of V REFIN I said low output impedance voltage reference comprising: a preamplifier, including a first plurality of interconnected transistors, having an input terminal coupled to the output terminal of the high output impedance voltage reference, with said preamplifier for preventing a substantial amount of current from flowing into or out of the output terminal of said high output impedance voltage reference and for providing first and second preamplifier output signals at first and second preamplifier output terminals, respectively; an isolation stage, including a second plurality of interconnected transistors, having first and second inputs coupled to said first and second preamplifier outputs and first and second output terminals, said isolation stage for isolating said preamplifier from the effects of an output voltage bounce and for increasing the current driving capability of the voltage reference; a source follower output stage, including a third plurality of interconnected transistors, having first and second inputs coupled to said first and second isolation stage outputs, respectively, and for providing the V REFOUT signal at an output stage output terminal and for providing a high source/sink current driving capability and low output impedance; and means for biasing the transistors in said first, second and third pluralities in the subthreshold region to minimise power dissipation.

Claim 5

The voltage reference as claimed in claims 1 or 2 wherein said means for biasing comprises: a current mirror being a circuit including the transistors in said first plurality.

Claim 6

The voltage reference as claimed in claim 3 wherein said current mirror includes a matched pair of transistors.

Claim 7

The voltage reference as claimed in claim 4 wherein said transistors in said matched pair are scaled to reduce the current flow in said current mirror to the subthreshold level.

Claim 8

A low poer, low output impedance on-chip CMOS voltage reference with high current drive capability for accepting a V REFIN signal from the output terminal of a high output impedance voltage reference and for providing a V REFOUT signal where the magnitude of V REFOUT is about equal to the magnitude of V REFIN , said low output impedance voltage reference comprising: a CMOS preamplifier, including a first plurality of interconnected PMOS and NMOS transistors, having an input terminal coupled to the output terminal of the high output impedance voltage reference, with said preamplifier for preventing a substantial amount of current from flowing into or out of the output terminal of said high output impedance voltage reference and for providing first and second preamplifier output signals at first and second preamplifier output terminals, respectively; a CMOS source follower output stage, including a second plurality of interconnected PMOS and NMOS transistors, having first and second inputs coupled to said first and second preamplifier outputs, respectively, and for providing the V REFOUT signal at an output stage output terminal and for providing a high source/sink current driving capability and low output impedance; and means for biasing the transistors in said first and second plurality in the subthreshold region to minimise power dissipation.

Claim 9

A low poer, low output impedance on-chip CMOS voltage reference with high current drive capability for accepting a V REFIN signal from the output terminal of a high output impedance voltage reference and for providing a V REFOUT signal where the magnitude of V REFOUT is about equal to the magnitude of V REFIN , said low output impedance voltage reference comprising: a CMOS preamplifier, including a first plurality of interconnected PMOS and NMOS transistors, having an input terminal coupled to the output terminal of the high output impedance voltage reference, with said preamplifier for preventing a substantial amount of current from flowing into or out of the output terminal of said high output impedance voltage reference and for providing first and second preamplifier output signals at first and second preamplifier output terminals, respectively; a CMOS source follower output stage, including a second plurality of interconnected PMOS and NMOS transistors, having first and second inputs coupled to said first and second preamplifier outputs, respectively, and for providing the V REFOUT signal at an output stage output terminal and for providing a high source/sink current driving capability and low output impedance; and means for biasing the transistors in said first and second plurality in the subthreshold region to minimise power dissipation.

Claim 10

A low power, low output impedance on-chip CMOS voltage reference with high current drive capability for accepting a V REFIN signal from the output terminal of a high output impedance voltage reference and for providing a V REFOUT signal where the magnitude of V REFOUT is about equal to the magnitude of VREFIN' said low output impedance voltage reference comprising: a CMOS preamplifier, including a first plurality of interconnected PMOS and NMOS transistors, having an input terminal coupled to the output terminal of the high output impedance voltage reference, with said preamplifier for preventing a substantial amount of current from flowing into or out of the output terminal of said high output impedance voltage reference and for providing first and second preamplifier output signals at first and second preamplifier output terminals, respectively; a CMOS isolation stage, including a second plurality of interconnected PMOS and NMOS transistors, having first and second preamplifier outputs and first and second output terminals, said isolation stage for isolating said preamplifier from the effects of an output voltage bounce and for increasing the current driving capability of the voltage reference; a CMOS source follower output stage, including a third plurality of interconnected PMOS and NMOS transistors, having first and second inputs coupled to said first and second isolation stage outputs, respectively, and for providing the V REFOUT signal at an output stage output terminal and for providing a high source/sink current driving capability and low output impedance; and means for biasing the transistors in said first, second and third pluralities in the subthreshold region to minimise power dissipation.

Claim 11

A low power, low output impedance on-chip CMOS voltage reference with high current drive capability for accepting a V REFIN signal from the output terminal of a high output impedance voltage reference and for providing a V REFOUT signal where the magnitude of V REFOUT is about equal to the magnitude of VREFIN' said low output impedance voltage reference comprising: a CMOS preamplifier, including a first plurality of interconnected PMOS and NMOS transistors, having an input terminal coupled to the output terminal of the high output impedance voltage reference, with said preamplifier for preventing a substantial amount of current from flowing into or out of the output terminal of said high output impedance voltage reference and for providing first and second preamplifier output signals at first and second preamplifier output terminals, respectively; a CMOS isolation stage, including a second plurality of interconnected PMOS and NMOS transistors, having first and second preamplifier outputs and first and second output terminals, said isolation stage for isolating said preamplifier from the effects of an output voltage bounce and for increasing the current driving capability of the voltage reference; a CMOS source follower output stage, including a third plurality of interconnected PMOS and NMOS transistors, having first and second inputs coupled to said first and second isolation stage outputs, respectively, and for providing the V REFOUT signal at an output stage output terminal and for providing a high source/sink current driving capability and low output impedance; and means for biasing the transistors in said first, second and third pluralities in the subthreshold region to minimise power dissipation.

Claim 12

The voltage reference as claimed in claims 6 or 7 wherein said means for biasing comprises: a CMOS current mirror being a circuit including the transistors in said first plurality.

Claim 13

The voltage reference as claimed in claim 8 wherein said current mirror includes a matched pair of transistors.

Claim 14

The voltage reference as claimed in claim 9 wherein the W/L ratio of the transistors in said matched pair are scaled to reduce the current flow in said current mirror to the subthreshold level.

Claim 15

The voltage reference as claimed in claim 10 wherein said low output impedance voltage reference is connected to the V cc and ground terminals of an external power supply, and where said CMOS current mirror includes first and second interconnected series circuits with said first circuit comprising: a first PMOS transistor having its source terminal connected to the V CC terminal and its drain terminal connected to a first circuit node; a second NMOS transistor having its drain terminal connected to said first circuit node and its source terminal connected to a second circuit node with the output terminal of said high output impedance voltage reference also coupled to said second circuit node; a third PMOS transistor having its source terminal connected to said second circuit node and its drain terminal connected to a third circuit node; a fourth NMOS transistor having its drain terminal connected to said third circuit node and its source connected to the ground terminal; with said second NMOS transistor being connected in the diode configuration with its gate connected to said first circuit node; with said third PMOS transistor being connected in the diode configuration to said third circuit node; with said first and third circuit nodes being the first and second output terminals, respectively, of said preamplifier; and with said second series circuit comprising: a fifth PMOS transistor having its source terminal coupled to the V CC terminal and its drain terminal connected to a fourth circuit node, with said fourth circuit node being coupled to the gate of said first transistor; a sixth NMOS transistor having its drain terminal connected to said fourth circuit node and its source terminal connected to a fifth circuit node, with the gate of said sixth transistor coupled to said first node; a seventh PMOS transistor having its source terminal connected to said fifth node and its drain terminal connected to a sixth circuit node, with the gate of said seventh transistor coupled to said third node; an eighth NMOS transistor having its drain terminal connected to said sixth node and its source terminal connected to the ground terminal, with said sixth node being coupled to the gate of said fourth transistor; with said fifth PMOS transistor being connected in the diode configuration with its gate connected to said fourth circuit node; with said eighth NMOS transistor being connected in the diode configuration with its gate connected to said sixth circuit node; with said first and fifth, second and sixth, third and seventh, and fourth and eighth transistors being matched transistor pairs; and with said first and third nodes being the first and second preamplifier output terminals.

Claim 16

The voltage reference as claimed in claim 11 wherein said output stage is a series circuit comprising: a ninth NMOS transistor having its drain terminal connected to the V CC terminal, and its source terminal connected to a seventh circuit node, and with said seventh node being the output terminal of said source follower; and a tenth PMOS transistor having its source terminal connected to said seventh circuit node, and its drain terminal connected to the ground terminal.

Claim 17

The voltage reference as claimed in claim 12 further including an isolation stage being a series circuit comprising: a thirteenth PMOS transistor having its source terminal connected to the V cc terminal, its drain terminal connected to a ninth circuit node, and its gate connected to said fourth circuit node; a fourteenth NMOS transistor having its drain terminal connected to said ninth circuit node and its source terminal connected to a tenth circuit node; a fifteenth PMOS transistor having its source terminal connected to said tenth circuit node and its drain terminal connected to an eleventh circuit node; a sixteenth NMOS transistor having its drain terminal connected to said eleventh circuit node, its source terminal coupled to the ground terminal, and its gate coupled to said sixth circuit node; with said fourteenth transistor connected in the diode configuration with its gate connected to said ninth circuit node; with the fifteenth transistor connected in the diode configuration with its gate coupled to said eleventh circuit node; with said first and thirteenth transistors, said second and fourteenth transistors, said third and fifteenth transistors, and said fourth and sixteenth transistors being matched transistor pairs; with said ninth and eleventh nodes being the first and second output terminals of said isolation stage; with said ninth node being coupled to the gate of said ninth transistor and said eleventh node being coupled to the gate of said tenth transistors, the gates of said ninth and tenth transistors being the input terminals of said source-follower; with said ninth and fourteenth and tenth and fifteenth transistors being matched transistor pairs; and with the W/L ratios of said ninth and tenth transistors being scaled up relative to the W/L ratios of the thirteenth and fifteenth transistors.

Claim 18

The voltage reference as claimed in claim 13 wherein the W/L ratios of said first and fifth and fourth and eighth transistors are scaled to reduce the current flow through said first and second circuits to the subthreshold level.

Claim 19

The voltage reference as claimed in claim 14 wherein the magnitude of V REFIN is between the absolute value of V TP and V CC - V TN -

Claim 20

The voltage reference as claimed in claim 15 further comprising: means for preventing the trapping of the first and third nodes at an incorrect output stage when V CC bumps from a first to a second level.

Claim 21

The voltage reference as claimed in claim 16 wherein said means for preventing comprises: a first capacitor C 1 , coupling the output terminals of the high output impedance voltage reference to said first node; a second capacitor C 2' coupling the output terminals of the high output impedance voltage reference to said third node; a third capacitor C 3 , coupling said fifth node to the ground terminal.

Claim 22

The voltage reference as claimed in claim 17 wherein said means for preventing comprises: means for transferring charge between said fourth and sixth nodes.

Claim 23

The voltage reference as claimed in claim 18 wherein said means for transferring comprises: a charge pump circuit connecting said fourth and sixth nodes.

Claim 24

The voltage reference as claimed in claim 19 wherein said isolation circuit further comprises: a fourth capacitor C 4 , coupling said ninth node to the ground terminal; and a fifth capacitor C S , coupling said eleventh node to the ground terminal; with C 4 and C 5 for decoupling output bounce.

Claim 25

The voltage reference as claimed in claim 16 wherein said output stage is a series circuit comprising: a ninth NMOS transistor having its drain terminal connected to the V CC terminal, its source terminal connected to a seventh circuit node, and its gate connected to said first circuit node; a tenth PMOS transistor having its source terminal connected to said seventh circuit node, its drain terminal connected to the ground terminal, and its gate connected to said third circuit node; with said second and ninth transistors being a matched transistor pair and with said third and said tenth transistors being a matched transistor pair, and with the W/L ratio of said ninth and tenth transistors being scaled up from the W/L ratios of said third and fourth transistors.

Claim 26

The voltage reference as claimed in claim 21 further comprising: means for isolating said first and third nodes from the effects of an output voltage bounce.

Claim 27

The voltage reference as claimed in claim 22 wherein said means for isolating comprises: a fourth capacitor C 4 , coupling said first node to the ground terminal; and a fifth capacitor C 5 , coupling said third node to the ground terminal.