Filter circuits with emitter follower transistors and servo loops, and associated methods and apparatuses, are disclosed herein. In some embodiments, a filter circuit may include: a resistor-capacitor network having an input to receive an input signal; an emitter follower transistor, coupled to the resistor-capacitor network, wherein the filter circuit has an output to provide an output signal from the emitter of the emitter follower transistor; a current source to provide a constant reference current; and a current-buffering servo loop circuit, coupled to the emitter follower transistor and the current source, including a current buffer and a controlled current sink to maintain the collector current and the emitter current of the emitter follower transistor equal to the constant reference current.
