SMALL MUTUAL CONDUCTANCE DIFFERENTIAL AMPLIFIER AND DRIVING METHOD THEREFOR

摘要

PROBLEM TO BE SOLVED: To provide a small-sized differential amplifier circuit by connecting a control terminal with one electrode through an impedance element and connecting one electrode to an output node. SOLUTION: One terminal of each transistor is connected to each output node (node 3 to M5 and node 4 to M6) and the other terminal of each transistor is connected to the gate of a current source M3 and that of current source M4. Two low-pass filters(LPF) are composed of the resistors of M5 and M6 and the gate channel capacitors of M3 and M4 and concerning a frequency lower than the cutoff of the LPF, a system is operated just like connecting nodes 3 and 5 and nodes 3 and 6. Since the output conductance of the transistor is smaller than mutual conductance, the amplification factor of an operational mutual conductance amplifier (OTA) is low in the case of low frequency and high in the case of high frequency. The cutoff frequency of the internally existence LPF applies the low folding point frequency of the passband of the entire OTA.