Circuit for comparing an input current with a threshold current

An electronic device comprising:

• a circuit for comparing an input current to a current threshold comprising
• a diode-connected transistor having a control terminal and to be biased with a first constant current and function in a saturation condition,
• a sense transistor having a control terminal and a conduction terminal and being mirrored to said diode-connected transistor and to be biased to function in a linear condition, and
• a load transistor having a control terminal, first and second conduction terminals, and to be coupled in series with said sense transistor and to be biased with a second constant current,
• said control terminals of said diode-connected transistor, said sense transistor, and said load transistor being coupled together,
• said first conduction terminal of said load transistor and said conduction terminal of said sense transistor to receive the input current so that an output voltage is available on said second conduction terminal of said load transistor with the output voltage representing a difference between the input current and the current threshold when the input current is larger than the current threshold.

An electronic device comprising:

• a circuit for comparing an input current to a current threshold comprising
• a diode-connected transistor having a control terminal and to be biased with a first constant current and function in a saturation condition,
• a sense transistor having a control terminal and a conduction terminal and being mirrored to said diode-connected transistor and to be biased to function in a linear condition,
• a load transistor having a control terminal, first and second conduction terminals, and to be coupled in series with said sense transistor and to be biased with a second constant current,
• said control terminals of said diode-connected transistor, said sense transistor, and said load transistor being coupled together,
• said first conduction terminal of said load transistor and said conduction terminal of said sense transistor to receive the input current so that an output voltage is available on said second conduction terminal of said load transistor with the output voltage representing a difference between the input current and the current threshold when the input current is larger than the current threshold, and
• a logic comparator coupled to said second conduction terminal of said load transistor and configured to generate a logic flag when the output voltage exceeds a threshold voltage,
• said diode-connected transistor, said sense transistor, and said load transistor each comprising a low-voltage MOS transistor.

A method of making a circuit for comparing an input current to a current threshold comprising:

• configuring a diode-connected transistor to be biased with a first constant current and function in a saturation condition;
• configuring a sense transistor to be mirrored to the diode-connected transistor and to be biased to function in a linear condition;
• coupling a load transistor in series with the sense transistor and configuring it to be biased with a second constant current;
• coupling control terminals of the diode-connected transistor, the sense transistor, and the load transistor together;
• and
• configuring the first conduction terminal of the load transistor and the conduction terminal of the sense transistor to receive the input current so that an output voltage is available on the second conduction terminal of the load transistor with the output voltage representing a difference between the input current and the current threshold when the input current is larger than the current threshold.