Analog Devices ADRV9001 User Manual page 111

Reference Manual
FREQUENCY HOPPING
Table 45. Frequency Hopping Modes of Operation (Continued)
Mode Transition Time
PLL Mux with hop table real- < channel setup + PLL
time process retune
PLL Retune with hop table > channel setup + PLL
real-time process retune
PLL Retune with dual hop and > channel setup + PLL
hop table real-time process retune
Fundamentally, the ADRV9001 defines two modes of PLL usage: PLL Mux and PLL Retune. The PLL Mux mode utilizes two PLLs. While one
PLL is in operation, the other one is tuning. The two PLLs are swapped during the transition time. This mode is suitable for use cases where
the transition time is not sufficiently long to complete channel setup and PLL tuning. By using two PLLs, the PLL being retuned can have a
maximum tuning time of one frame length plus one transition time or equivalently two transition times plus one dwell time. On the other hand,
the PLL Retune mode is suitable for use cases where the transition time is sufficiently long that once a PLL finishes its operation, it can start
tuning and the channel setup and retuning can be completed within the transition time.
The ADRV9001 provides two modes of retuning the PLL: the normal mode and fast mode, as described in
the hop frames are short. Therefore, the fast Mode is usually sufficient. Currently, all FH modes use the Fast PLL calibration mode only.
The following timing diagram describes the PLL Mux mode.
Figure 104 shows that each hop frame consists of a transition time period and a dwell time period, as mentioned earlier. While one PLL is used
during the dwell time, the other PLL starts tuning from the beginning of the transition time of the same hop frame. It can continue the tuning until
the end of the transition period of the next hop frame. Then, the two PLLs are swapped during the transition time.
Note in the PLL Mux mode, the rising edge of Tx_Setup or Rx_Setup before a HOP signal edge (the start of hop frame n or end of hop frame
n-1) indicates if the hope frame n+1 is operated on Tx or Rx. There is one frame delay in the PLL Mux mode. In another word, to operate Tx on
hope frame n+1, the rising edge should appear at hop frame n-1.
analog.com
Total Frame Duration
(Transition + Dwell) PLLs
>= 25 µs 2 PLLs
Transition time >= 48 µs and 1 PLL
total frame duration > transition
time
Transition time >= 48 µs and 1 PLL
total frame duration > transition
time
Figure 104. PLL Mux Timing Diagram Example
Max PLL Retune PLL Cal
Time Allowed Mode
2 transitions + 1 dwell Fast Cal
mode
1 transition Fast Cal
mode
1 transition Fast Cal
mode
RF Synthesizer. For FH, typically,
ADRV9001
Channel
Single/Dual (1T/1R/1T1R or
2T/ 2R/2T2R diversity)
Single/Dual (1T/1R/1T1R or
2T/ 2R/2T2R diversity)
Dual (2T/2R/2T2R
multiplexing)
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