Polarization of a transistor in a radio-frequency amplifier stage, uses current sources to provide feedback control and variation of impedance seen by transistor input

摘要

The polarization device has feedback control (SCOMP, ICOMP) of transconductance, so the time average of input potential of the amplifier transistor (Q1) tracks a reference potential corresponding to desired transistor quiescent current. Seen from the input of the transistor, the impedance (R1,ICTRL) of the surrounding circuit is low at low frequencies and high at radio frequencies.