The QFN package of the prototype was mounted to an evaluation test board, see Fig. \ref{PCB}. One SMA connector was used to supply the RF and LO signals, and an SMA connector was used to measure the IF. Moreover, A second SMA was used to tested LO without the buffer as a mixer. Also, the prototype uses a four bias voltage, the first is the $V_{DD}$ of the ring oscillator, the second is $V_{DD}$ of the buffer as a mixer, the third is $V_{DD}$ of buffer without a mixer, and finally, the voltage for EDS protection.\\ …show more content…
\ref{S11} show both measured and simulated impedance matching performance. $S11$ of the prototype receiver was measured with RF signal bonded a network pi. The inconsistency between simulated and measured results presented at $1.5-2GHz$ and $2.4GHz$ is due to the interconnection between of-chip coupling network at the RF input, the FR-4 PCB, and, package effects. The WBAN has a working frequency of $2.36GHz$ at $2.48GHz$with a channel bandwidth of $1MHz$. The $S11$ at $2.36GHz$ is $-13dB$. However, at $2.48GHz$ is $-3.6dB$. Hence, the input match on the last channel has the biggest losses by return.