| 摘要 |
PURPOSE:To increase the gain variable width by separating input/output use field effect transistors (TRs) and using a couple of voltage gain controlled field effect TRs so as to exclude the effect of leakage of an input voltage. CONSTITUTION:A channel resistor of the controlled field effect TRs 11, 12 is selected as RC, then a transfer conductance GC of a circuit C shown in broken lines is expressed as GC=GM/(1+RCXGM), where GM is the transfer conductance of the voltage amplification field effect TRs 6, 8. Thus, the voltage gain is expressed as RLXGM/2(1+RCXGM), where RL is the resistance of load resistors 2, 3 respectively and the output voltage is reduced as the channel resistor RC of the control TRs 11, 12 is increased. The input voltage leaked from the gate of the field effect TR 6 to the drain is outputted via a large resistance between the drain and source of the field effect TR 8 only, the leaked voltage is decreased by 40dB or over. Thus, the voltage gain variable range is increased by 40dB or over.
|
