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FREQUENCY DIVIDERS & DETECTORS - SMT
22
HMC983LP5E
v02.0112
DC - 7 GHz FRACTIONAL-N DIVIDER
AND FREQUENCY SWEEPER
Table 6. DC - 7 GHz FRACTIONAL-N DIVIDER Sweeper Conguration Sequence
Steps Description
Sweeper Modes
2-Way Sweep Mode User Dened Sweep Mode 1-Way Sweep Mode
1Lock to start
frequency (fo)
•set the integer (Reg 05h) and fractional (Reg 06h and Reg 07h) divider values.
•Optionally, if required the seed (Reg 0Ah and Reg 0Bh) can also be programmed
2Place the DSM
in sweep mode •Write Reg 0Eh[11] = 1
3Congure
sweep mode
•Disable single step ramp mode (Reg
0Eh[24] = 0), so that each frequency
increment will be incremented
automatically
•Enable 2-way sweep mode (Disable
1-way sweep mode (Reg 0Eh[25]
= 0))
•T o place the DC - 7 GHz FRACTIONAL -N DIVIDER
in automatic sweep mode write
Reg 0Eh[2:3] = ‘11’. To place the
DC - 7 G Hz FR ACTIO N AL-N DIV IDER i n
triggered mode write Reg 0Eh[2:3] =
‘00’.
•Enable the single step ramp mode
(Reg 0Eh[24] = 1), so that each
frequency increment will require a
trigger
•Enable 1-way sweep mode (Reg
0Eh[25] = 1), or enable 2-Way
sweep mode (Reg 0Eh[25] = 1)
•T o place the DC - 7 GHz FRACTIONAL -N DIVIDER
in triggered mode write Reg 0Eh[2:3]
= ‘00’. Automatic User Dened
Sweep mode is not supported.
•Disable single step ramp mode (Reg
0Eh[24] = 0), so that each frequency
increment will be incremented
automatically
•Enable 1-way sweep mode (Reg
0Eh[25] = 1)
•T o place the DC - 7 GHz FRACTIONAL -N DIVIDER
in triggered mode write Reg 0Eh[2:3]
= ‘00’. Automatic 1-Way Sweep
mode is not supported.
4
Program
Sweep
Direction
•Reg 0Eh[26] = 1 begin sweep in positive direction, Reg 0Eh[26] = 0 begin sweep in negative direction
5
Congure
symmetrical/
asymmetrical
sweep
•Program ramp mode (symmetrical - Reg 0Eh[22] = 1, asymmetrical - Reg
0Eh[22] = 0). If symmetrical ramp mode is selected (Reg 0Eh[22] = 1), only
Up sweep parameters will be used for both positive and negative sweeps,
and hence down sweep parameters don’t need to be programmed. In
symmetrical ramp mode the positive and negative ramps are identical and
opposite in direction.
•Program Reg 0Eh[22] = 1.
Asymmetrical sweep is not dened
in 1-Way Sweep mode
6
Program
Up Sweep
Parameters
•Set dwell time(dwell time[47:0] = Reg 10h[29:0], dwell time[17:0] = Reg 11h [17:0])
•Set step size (step size[47:18] = Reg 12h[29:0], step size[17:0] = Reg 13h[17:0])
•Set the number of steps in a sweep (number of steps[47:18] = Reg 14h[29:0], number of steps[17:0] = Reg 15h[17:0])
7
Program
Down Sweep
Parameters
(Only if using
asymmetrical
sweep (if Reg
0Eh[22] = 0) in
Step 5)
•Set dwell time (dwell time[47:0] = Reg 06h[47:18], dwell time[17:0] = Reg
07h[17:0])
•Set step size (step size[47:18] = Reg 19h[29:0], step size[17:0] = Reg
1Ah[17:0])
•Set the number of steps in a sweep (number of steps[47:18] = Reg 0Ch[29:0],
number of steps[17:0] = Reg 0Dh[17:0])
•Asymmetrical sweep is not dened
in 1-Way Sweep mode
8Congure and
apply trigger
•To use SPI trigger write Reg 0Eh[13] = 0 to select SPI trigger. SPI trigger is executed by writing to Reg 0Eh[12] = 1.
•To use external trigger on pin D4 write Reg 0Eh[13] = 1 to congure pin D4 as an external trigger. Write Reg 08h[13]
= 0h to congure pin D4 to be an input. Applying master enable to GPIO pins (Reg 01h[4] = 1 ) is required.
•Enable trigger delay (Reg 0Eh[7] = 1), or disable trigger delay (Reg 0Eh[7] = 0).
•If using trigger delay, write delay value to Reg 05h[20:0], where Reg 05h[20:0] = number of delayed reference
periods. Writing Reg 05h[20:0] = 1 for example ensures that the trigger is applied at the instant of the rising edge
of the next reference rising edge.
DC - 7 GHz FRACTIONAL-N DIVIDER sweep parameters are dened in the following way:
fo Initial frequency of the synthesizer
ff Frequency of the synthesizer at the end of the sweep
R Reference divider value(Reg 02h[13:0])