A 300 MHz 18 dB variable gain amplifier

This paper presents a very linear variable gain amplifier (VGA) which requires no capacitor or resistor array. Due to its special structure, the circuit does not trade bandwidth for gain. Thus, bandwidth is almost independent of gain. Although the proposed VGA consumes a small amount of power, 22 mW, from a 3.3 volt supply it has a 310 MHz -3 dB bandwidth. THD simulation results are -45 dB for a 800 mV p-p input, at 0 dB gain.