Variable gain amplifier

摘要

A variable gain amplifier includes a voltage divider input stage for receiving a signal to be amplified. A first voltage amplifier is connected in cascade with the voltage divider for amplifying the signal to be amplified. The voltage divider input stage includes a variable impedance circuit having a second voltage amplifier. The second voltage amplifier includes an input and an output. An impedance element is connected between the voltage amplifier input and output. The voltage divider input stage is connected in series to a second impedance element. Each of the voltage amplifiers has its gain controlled by a bias current source.