|IFA consists of 3-stages amplifier with tunable gain, AGC system, linear output buffer for differential analog output, analog-digital converter for 2-bits digital output. Each stage of the amplifier has differential input and output. Gain is sequentially reduced from the last stage to the first stage. Also gain can be fixed by the digital code DAC 9:0. The block is fabricated on TSMC018 SiGe technology.