Analysis of NMR Spectrometer Receiver Noise Figure

Figure 1

A simplified circuit diagram of the NMR receiver. (a) Signal and noise voltages at the two-port, (b) incoming noise power at the two-port. : group of incoming signal or noise voltages, e.g., , , , or . : group of outgoing signal or noise voltages, e.g., , , , or (i-th term of the samples series). is the noise bandwidth of the receiver. The noise spectra within the noise bandwidth should be constant. is signal voltage from source. are resistances of source, input resistance of the two-port, and load resistance of the two-port. is the absolute temperature of the resistance . is RMS value of the thermal noise voltage generated in the resistance (Nyquist equation). is the noise power from incoming into the two-port.

(a)

(b)