International Symposium on Antennas and Propagation
A Dual-Band Low-Noise Amplifier with Controllable Gain
Chia-Hao Chang, Jean-Fu Kiang,
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The WLAN systems operate in the 2.4 GHz (e.g., Bluetooth, IEEE 802.1l b/g) and 5.2 GHz (e.g., IEEE 802.1l a) frequency bands. Conventional dual-band RF circuit designs take two parallel LNAs , hence will take more chip area, and LC networks are usually used to match both the input and output ports at two different bands , , . The fading effect tends to degrade the LNA performance, hence the LNA is desired to have an increased dynamic range of RF signals. The gain control circuit in LNA is intended to solve this problem, typical approaches include current splitting and shunt-feedback , . In this paper, a design method of a dual-band LNA with controllable gain is proposed and fabricated in a standard TSMC 0.18 μm CMOS technology, in which LC matching network is used to match at 2.4 GHz and 5.2 GHz at four gain modes.