US 2006/0214695 A1 · Keeper circuits having dynamic leakage compensation

Abstract

Disclosed are keeper circuits for electronic circuits that selectively maintain the voltage level of an intermediate circuit node at a desired level. In one exemplary embodiment, a keeper transistor either provides current or drains current from the intermediate node to maintain the desired voltage level in response to a signal to do so. The keeper circuit works against a leakage current that either drains current from the node or supplies current to the node. A current-setting transistor is coupled in series with the keeper transistor to set the maximum current through the keeper circuit to a value that is related to this leakage current, preferably tracking the leakage current. With this construction, the current-setting transistor is able to track variations in the leakage current caused by variations in the manufacturing process, and thereby provide dynamic leakage compensation.

Claims42

Dependent claims

A keeper circuit for use in a circuit powered by a voltage provided between a first supply line and a second supply line, the keeper circuit for selectively maintaining an intermediate node of the circuit at a first voltage level in opposition to a leakage current being conducted between the intermediate node and the second supply line, the keeper circuit comprising:

a keeper transistor having a first conduction terminal, a second conduction terminal, and a modulation terminal, the modulation terminal receiving a signal indicating whether the keeper transistor is to maintain an intermediate node at a first voltage level;
a first transistor of a first conductivity type having a first conduction terminal a second conduction terminal, and a modulation terminal, one of the conduction terminals of the first transistor being coupled to a conduction terminal of the keeper transistor to provide a series circuit of the transistors, the series circuit being coupled between the intermediate node and the first supply line;
a second transistor of the first conductivity type having a first conduction terminal, a second conduction terminal, and a modulation terminal, the second transistor being coupled to the first transistor in a current-mirror relationship such that the maximum amount of current conducted by the first transistor through its conduction terminals is related to the current conducted by the second transistor through its conduction terminals;
and
a sensing network having a first conduction terminal coupled to the first conduction terminal of the second transistor and a second conduction terminal coupled to a source of potential, the sensing network comprising at least one transistor of a second conductivity type opposite to the first conductivity type and generating a current at its first conduction terminal that is in relation to the leakage current being conducted between the intermediate node and the second supply line.

2 more elements

A keeper circuit for use in a digital circuit powered by a voltage provided between a first supply line and a second supply line, the keeper circuit for selectively maintaining an intermediate node of the digital circuit at a first voltage level, the keeper circuit comprising:

a keeper transistor having a first conduction terminal, a second conduction terminal, and a modulation terminal, the modulation terminal receiving a signal indicating whether the keeper transistor is to maintain an intermediate node at a first voltage level,
a first PMOS transistor having a drain terminal, a source terminal, and a gate terminal, one of the source and drain terminals of the first PMOS transistor being coupled to a conduction terminal of the keeper transistor to provide a series circuit of the transistors, the series circuit being coupled between the intermediate node and the first supply line;
a second PMOS transistor having a drain terminal, a source terminal, and a gate terminal, the second PMOS transistor being coupled to the first PMOS transistor in a current-mirror relationship such that the maximum amount of current conducted by the first PMOS transistor through its drain and source terminals is related to the current conducted by the second PMOS transistor through its source and drain terminals;
and
at least a first NMOS transistor having a drain terminal coupled to the drain terminal of the second PMOS transistor, a source terminal, and a gate terminal, wherein the gate terminal and the source terminal are coupled together and to a source of potential.

2 more elements

a keeper transistor having a first conduction terminal, a second conduction terminal, and a modulation terminal, the modulation terminal receiving a signal indicating whether the keeper transistor is to maintain an intermediate node at a first voltage level;
characterized by a current-setting transistor having a first conduction terminal, a second conduction terminal, and a modulation terminal, the current-setting transistor being configured to set the maximum current flow between its first and second conduction terminals in relation to the leakage current being conducted between the intermediate node and the second supply line;
and
characterized in that a conduction terminal of the keeper transistor is coupled to a conduction terminal of the current-setting transistor to provide a series circuit of the transistors, and in that the series circuit is coupled between the intermediate node and the first supply line.

1 more element

Dependencies are inferred from the claim text.

Keeper circuits having dynamic leakage compensation

Life of this patent

Keeper circuits having dynamic leakage compensation

Life of this patent

Abstract

Claims42