| 摘要 |
A transconductance amplifier having a transconductance tunable in a wider range while the linearity between the input voltage and output current over the whole predetermined operation input range is maintained. An example of the invention comprises a differential pair composed of source-grounded first and second MOS transistors (111, 112), third and fourth transistors (113, 114) whose source terminals are connected to the respective drain terminals of the first and second transistors (111, 112), a voltage generating circuit (300) for outputting a tuning voltage and a common voltage at a constant ratio of the common and tuning voltages, and a differential pair input voltage generating circuit (320) which receives the input voltage and the common voltage and outputs a voltage Vip and a voltage Vin to the respective gate terminals of the first and second transistors (111, 112). The gate terminal of the fourth transistor (114) is connected to the gate terminal of the third transistors (113), and the tuning voltage is inputted to both gate terminals. |
