Four-quadrant multiplier for operation of MOSFET devices in saturation region

A four-quadrant multiplier, comprising:

• a first differential input circuit having
• a first field effect transistor which produces a first drain current proportional to the square of a difference between a first gate voltage applied thereto and a first gate threshold voltage thereof, and
• a second field effect transistor which produces a second drain current proportional to the square of a difference between a second gate voltage applied thereto and a second gate threshold voltage thereof;
• a second differential input circuit having
• a third field effect transistor which produces a third drain current proportional to the square of a difference between a third gate voltage applied thereto and a third gate threshold voltage thereof, and
• a fourth field effect transistor which produces a fourth drain current proportional to the square of a difference between a fourth gate voltage applied thereto and a fourth gate threshold voltage thereof;
• a DC current supply circuit having
• two field effect transistors arranged to form a current mirror and having drains,
• two output nodes, and
• three constant current sources, each constant current source producing a same constant current, such that the DC current supply circuit provides the same constant current between each of the output nodes and a source supply voltage, and also provides the same constant current between a drain supply voltage and the drains of said two field effect transistors;
• a current transfer circuit for producing an output current by subtracting the third and fourth drain currents from the sum of the first and second drain currents.