Agilent Technologies 85032B/E 50 Specifiche Pagina 226

  • Scaricare
  • Aggiungi ai miei manuali
  • Stampa
Vedere la pagina 225
8712ET/ES and 8714ET/ES Theory of Operation
RF Network Analyzers System Theory
Service Guide 6-11
In band 1, below 1.91 GHz, the source is very similar to that of the 8712ET/ES. However,
the fractional-N input is first divided by 7 instead of 4, the source LO is divided by 512
instead of 256, and the RF1 signal is 2339.777778 instead of 2340 MHz. The formula for a
Fractional-N to RF output frequency is therefore:
RF
out
= (Fractional-N × 512/7) 2339.777778
(all frequencies in MHz)
This is very similar to the 8712ET/ES formula:
RF
out
= (Fractional-N × 256/4) 2340
The 8714ET/ES fractional-N input frequency will vary from about 32 to 58 MHz as
opposed to the 8712ET/ES variation of about 36.6 to 57 MHz. In both cases the pulse
swallow circuitry maintains the RF2 signal to be 27.778 kHz below the RF1 signal so that
the final LO will be 27.778 kHz above the RF, thus generating the proper IF.
In bands 2 through 4, above 1.91 GHz, the RF1 and RF2 signals are divided by 2 to provide
an RF1 frequency of 1169.777778 MHz (the ratio is not exactly 1/2 due to differences in the
way the pulse swallow circuitry works). The formula for RF output frequency now
becomes:
RF
out
= (Fractional-N × 512/7) 1169.777778
The Fractional-N signal now varies from about 42 to 57 MHz to provide the 1910 to
3000 MHz RF output in bands 2 through 4. This means that during a full band sweep of
0.3 MHz to 3 GHz, the fractional-N output will first sweep from about 32 to 58 MHz, then
reset to 42 MHz, and sweep again up to 57 MHz.
Vedere la pagina 225
1 2 ... 221 222 223 224 225 226 227 228 229 230 231 ... 268 269

Commenti su questo manuale

Nessun commento