US 8,575,969 B2 · Semiconductor device having differential pair transistors with a switchable tail current

Abstract

A semiconductor device configured that its differential pair is made operable in both states of high speed with a high consumption current and low speed with a low consumption current. A differential circuit includes differential pair transistors and a tail current source for supplying a tail current that is switchable so that an amount of current flowing in the differential pair transistors may be switched between at least two sates of different levels. The differential pair transistors have a characteristic that, with a decrease of currents flowing in the differential pair transistors, a value of σ(ΔI/gm) decreases monotonously, where σ denotes a standard deviation, ΔI denotes a difference of the amounts of current of the differential pair transistors, and gm denotes transconductance of the differential pair transistors.

Claims17

Dependent claims

A semiconductor device comprising:

differential pair transistors;
and
a tail current source configured to supply switchable tail current so that an amount of current flowing in the differential pair transistors takes at least first current value and second current value smaller than the first current value,
wherein the differential pair transistors have each a characteristic that, with a decrease of the current flowing in the differential pair transistor, a value of σ(ΔI/gm) decreases monotonously,
where σ denotes a standard deviation, ΔI denotes a difference of the amounts of current of the differential pair transistors, and gm denotes transconductance of the differential pair transistors, and
wherein the differential pair transistors are configured to operate in a strong inverse region with the tail current having the first current value, and are configured to operate in a moderate inversion region or a weak inversion region with the tail current having the second current value.

3 more elements

A semiconductor device, comprising:

differential pair transistors, each having a gate formed in a shape of a ring covering an adjoining region between an isolation region and an active region on a source side;
and
a tail current source configured to supply switchable tail currents so that an amount of current flowing in the differential pair transistors takes at least first current value and a second current value smaller than the first current value,
wherein the differential pair transistors are configured to operate in a strong inverse region with the tail current having the first current value, and are configured to operate in a moderate inversion region or a weak inversion region with the tail current having the second current value.

1 more element

Dependencies are inferred from the claim text.

Semiconductor device having differential pair transistors with a switchable tail current

Life of this patent

Semiconductor device having differential pair transistors with a switchable tail current

Life of this patent

Abstract

Claims17