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US 5,512,855 AGranted
Constant-current circuit operating in saturation region
AssigneeNEC Corporation
InventorKatsuji Kimura
Life of this patent
Estimating the term…
Abstract
A constant-current circuit which has four MOS transistors. The first and second MOS transistors are driven at a constant current ratio corresponding to a ratio of gate-width and gate-length ratios of the third and fourth MOS transistors. The third and fourth MOS transistors are configured as a current mirror circuit, and are chosen to have different gate-width and gate-length ratios from one another.
Claims14
A constant-current circuit comprising:
- a first MOS transistor;
- a second MOS transistor;
- a current mirror circuit comprising a third MOS transistor and a fourth MOS transistor different in gate-width and gate-length ratio from each other,
- wherein said first MOS transistor has a drain and a gate connected through a resistor to each other and is supplied through said resistor with a first driving current from said third MOS transistor of said current mirror circuit, and
- said second MOS transistor has a gate connected to a drain of said first MOS transistor and a drain directly receiving a second driving current from said fourth MOS transistor of said current mirror circuit,
- said first, second, third and fourth MOS transistors operating in saturation regions,
- whereby said first and second MOS transistors are driven at a constant current ratio corresponding to a ratio of gate-width and gate-length ratios of said third and fourth MOS transistors,
- one of said first and second driving currents being used as a constant current.
5 more elements
A constant-current circuit comprising:
- a first MOS transistor;
- a second MOS transistor;
- and
- a current mirror circuit comprising third and fourth MOS transistors different in gate-width and gate-length ratio from each other,
- wherein said first MOS transistor has a drain and a gate connected directly to each other and receives a driving current directly from said current mirror circuit,
- said second MOS transistor has a source connected to a resistor and a gate connected to a drain of said first MOS transistor and a drain directly receiving a driving current from said current mirror circuit, and
- said first, second, third and fourth MOS transistors operating in saturation regions,
- whereby said first and second MOS transistors are driven at a constant current ratio corresponding to a ratio of gate-width and gate-length ratios of said third and fourth MOS transistors, one of said first and second driving currents being used as a constant current.
5 more elements
Dependencies are inferred from the claim text.