Handheld NMR Systems and Their Applications for Biomolecular Sensing - Point-of-Care Diagnostics on a Chip - page 182

Fig. 8.8 Measured receiver output power spectrum for a -100-dBm, 21-MHz RF signal and with
a 21.003-MHz square wave LO

chip, on which an aqueous sample is placed, is left exposed while the rest of the
chip is encapsulated.

8.3.1 Receiver Measurement

To measure the receiver input-referred noise, we feed a 100-dBm, 21-MHz RF
signal to the receiver's LNA input and use a 21.003-MHz square wave as a
local oscillator signal. From the signal and noise power spectrum measured at
the receiver's mixer output (Fig. 8.8 ) using an Agilent E4448 spectrum analyzer,
the receiver gain is inferred, and then, by dividing the measured output noise

with the gain, the receiver input-referred noise of 1:26 nV= p H z is extracted. In
this process, the image effect due to the frequency down-conversion is factored