| 摘要 |
PROBLEM TO BE SOLVED: To provide a tunable MOS type OTA, which enables four-quadrant operation, by appropriately setting the values of first and second constant currents. SOLUTION: A first transistor pair 1 is driven by a constant current Ib1 generated by a constant current source 6, and a second transistor pair 2 is driven by a constant current Ib2 generated by a constant current source 7. An input voltage Vi is differentially inputted to an input terminal pair. A sum current I1 of currents to flow to second and third transistor pairs 2 and 3 is inputted to the first input terminal of a current subtracter 1, and a sum current I2 of currents to flow to first and fourth transistor pairs 1 and 4 is inputted to the second input terminal. The current subtracter 5 subtracts the inputted currents I1 and I2 outputs an output currentΔI. The output currentΔI is made linear in respect to the input voltage Vi and at the same time, transconductance is changed corresponding to the current values Ib1 and Ib2 of the constant current sources 6 and 7. Then, the current values of the constant current sources 6 and 7 are appropriately set. |
