A Low Power Interference Robust IR-UWB Transceiver SoC for WBAN Applications - Ultra-Wideband and 60 GHz Communications for Biomedical Applications - page 39

a b

Fig. 17 a Measured low noise amplifier (LNA) S 11 and S 21 in high/low gain mode. b Measured
noise figure in high/low gain mode

Fig. 18 Measured low noise
amplifier (LNA) IIP3 at
4.0 GHz

Fig. 19 Measured squarer
output voltage versus input
power

headroom. Nevertheless, the output saturation can be avoided by switching the gain
of LNA to adjust the squarer input power. After 50 dB attenuation, the transmitting
pulse is fed into the receiver and Fig. 20 a shows the time-domain output signal.
Band-pass characteristic of squarer output spectrum is shown in Fig. 20 b. The lower
3 dB cut-off frequency is 50 MHz which is sufficient to filter out the down-converted
NBI signal.