Optimizing Fast Power ACLR Measurements with the N9042B and N9032B X-Series Signal Analyzers
Application Notes
Wideband “Fast Power” with the N9042B and N9032B
The N9042B and N9032B Analyzers (Option FP2) have a FFT based “Fast Power” (FP) measurement feature with instantaneous bandwidths selectable up to 2 GHz (Table 1), for capturing Channel Power and ACLR of multiple channels in one shot. After choosing the appropriate bandwidth option, but prior to taking a measurement these analyzers must be set up for the best dynamic range so that the ACLR floor of the instrument is the lowest achievable and significantly below that of the DUT. To achieve the best dynamic range at a given power level, there’s a trade-off involved between noise and non-linearity settings of the N9042B that include a) 0 to 70 dB range Attenuator, b) Signal Path with choice of four active gain states of the RF front-end, and c) -32 to +32 dB IF Gain range. These three individual settings (Table 2) need to be optimized at each power level of the input signal which is typically swept over a very wide power range for 5G NR wideband applications. Automating this optimization process is essential, and two methods are described in this paper:
- User-defined Model based on conditional statements
- Expert System generated Model