Figure 3
From: Out-of-band and adjacent-channel interference reduction by analog nonlinear filters
Instantaneous power response of quadrature receiver tuned to the RX frequency f RX (in the 1- to 3-GHz range). The transmitted signal is in a 5-MHz band around 2 GHz, the transmit power is 125 mW (21 dBm), and the path/coupling loss is 50 dB. Panels I(a) and I(b): wide bandwidth of the lowpass filter (40-MHz eighth-order Butterworth filter) without (panel I(a)) and with (panel I(b)) thermal noise. Panels II(a) and II(b): narrow bandwidth of the lowpass filter (5-MHz eighth-order Butterworth filter) without (panel II(a)) and with (panel II(b)) thermal noise. The impulse response (time window) w(t) of the lowpass filter is shown in the upper left corners of the respective panels.