US 5,473,283 AGranted

Cascode switched charge pump circuit

AssigneeNational Semiconductor Corporation

InventorThomas M. Luich

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Abstract

A low leakage, metal oxide semiconductor field effect transistor (MOSFET) charge pump circuit includes P- and N-MOSFET current mirrors, P- and N-MOSFET current switches and an output node. The P-MOSFET current mirror sources an output current which is switched by the P-MOSFET current switch in accordance with a pump-up control signal to provide a pump-up current. The width of the channel of the P-MOSFET current switch is substantially less than the sum of the widths of the channels of the P-MOSFETs of the P-MOSFET current mirror. The N-MOSFET current switch, in accordance with a pump-down control signal, switches a pump-down current which is sunk by the N-MOSFET current mirror. The width of the channel of the N-MOSFET current switch is substantially less than the sum of the widths of the channels of the N-MOSFETs of the N-MOSFET current mirror. The output node couples the P- and N-MOSFET current switches and receives the pump-up current and provides the pump-down current to provide a net charge pump signal suitable for use by a voltage controlled oscillator within a phase lock loop.

Claims27

Dependent claims

An apparatus including a low leakage, metal oxide semiconductor field effect transistor (MOSFET) charge pump circuit, said MOSFET charge pump circuit comprising:

a first output current source including a first plurality of MOSFETs for sourcing a first output current, wherein said first plurality of MOSFETs includes a first plurality of MOSFET channels with a first plurality of channel widths;
a first output controller including a first MOSFET, coupled to said first output current source, for receiving a pump-up control signal and said first output current and in accordance therewith providing a pump-up current, wherein said first MOSFET includes a first MOSFET channel with a first channel width, and wherein said first channel width is substantially less than a sum of said first plurality of channel widths;
a second output current source including a second plurality of MOSFETs for sinking a second output current, wherein said second plurality of MOSFETs includes a second plurality of MOSFET channels with a second plurality of channel widths;
a second output controller including a second MOSFET, coupled to said second output current source, for receiving a pump-down control signal and a pump-down current and in accordance therewith providing said second output current, wherein said second MOSFET includes a second MOSFET channel with a second channel width, and wherein said second channel width is substantially less than a sum of said second plurality of channel widths;
and
an output node, coupling said first and second output controllers, for receiving said pump-up current and providing said pump-down current.

3 more elements

A method of providing an apparatus including a low leakage, metal oxide semiconductor field effect transistor (MOSFET) charge pump circuit, said method comprising the steps of:

providing a first output current source including a first plurality of MOSFETs for sourcing a first output current, wherein said first plurality of MOSFETs includes a first plurality of MOSFET channels with a first plurality of channel widths;
providing a first output controller including a first MOSFET, coupled to said first output current source, for receiving a pump-up control signal and said first output current and in accordance therewith outputting a pump-up current, wherein said first MOSFET includes a first MOSFET channel with a first channel width, and wherein said first channel width is substantially less than a sum of said first plurality of channel widths;
providing a second output current source including a second plurality of MOSFETs for sinking a second output current, wherein said second plurality of MOSFETs includes a second plurality of MOSFET channels with a second plurality of channel widths;
providing a second output controller including a second MOSFET, coupled to said second output current source, for receiving a pump-down control signal and a pump-down current and in accordance therewith outputting said second output current, wherein said second MOSFET includes a second MOSFET channel with a second channel width, and wherein said second channel width is substantially less than a sum of said second plurality of channel widths;
and
providing an output node, coupling said first and second output controllers, for receiving said pump-up current and outputting said pump-down current.

3 more elements

A method of providing a charge pump signal with an apparatus including a low leakage, metal oxide semiconductor field effect transistor (MOSFET) charge pump circuit, said method comprising the steps of:

sourcing a first output current with a first output current source including a first plurality of MOSFETs which includes a first plurality of MOSFET channels with a first plurality of channel widths;
receiving a pump-up control signal and said first output current and in accordance therewith outputting a pump-up current with a first output controller including a first MOSFET with a first MOSFET channel having a first channel width which is substantially less than a sum of said first plurality of channel widths;
sinking a second output current with a second output current source including a second plurality of MOSFETs which includes a second plurality of MOSFET channels with a second plurality of channel widths;
receiving a pump-down control signal and a pump-down current and in accordance therewith outputting said second output current with a second output controller including a second MOSFET with a second MOSFET channel having a second channel width which is substantially less than a sum of said second plurality of channel widths;
and
receiving said pump-up current and outputting said pump-down current with an output node and in accordance therewith generating a charge pump signal.

3 more elements

Dependencies are inferred from the claim text.