An ultra-low power (ULP) sub-threshold CMOS
low noise amplifier (LNA) with tunable input matching for
2.4 GHz ISM band wireless sensor network applications is
presented. A mathematical approach has been presented to
find input matching network for any type of impedance transformation like complex to complex and complex to real. An
Impedance transformation using parallel inductor sub-threshold
LNA topology has been presented for IEEE 802.15.4a standard
using a standard low cost 0.18m RF CMOS process. The
inductive source degeneration is avoided here to facilitate higher
gain, better figure of merit with less area. Continuously tuned
characteristics are obtained by employing a switch and varactor
tuning techniques for the input matching circuit is configured. It
covers the frequency band between 2.2 GHz and 2.55 GHz and
obtains gain of 24dB, a noise figure of 3.6dB with P1dB of -5
dBm. It draws 0.532 mA from 1.8 V supply voltage.
Index Terms—ULP Sub Threshold LNA, Input Matching,
Switch Tuning, Varactor Tuning