A 0.1−5.1 GHz high-gain LNA with inductorless composite resistor−capacitor feedback structure based on a 0.25 μm SiGe BiCMOS process

In this paper, a high-gain inductorless LNA (low-noise amplifier) compatible with multiple communication protocols from 0.1 to 5.1 GHz is proposed. A composite resistor−capacitor feedback structure is employed to achieve a wide bandwidth matching range and good gain flatness. A second stage with a Darlington pair is used to increase the overall gain of the amplifier, while the gain of the first stage is reduced to reduce the overall noise. The amplifier is based on a 0.25 μ m SiGe BiCMOS process, and thanks to the inductorless circuit structure, the core circuit area is only 0.03 mm 2 . Test results show that the lowest noise figure (NF) in the operating band is 1.99 dB, the power gain reaches 29.7 dB, the S 11 and S 22 are less than −10 dB, the S 12 is less than −30 dB, the IIP3 is 0.81dBm, and the OP 1dB is 10.27 dBm. The operating current is 31.18 mA at 3.8 V supply.