HMC702LP6CE datasheet(23/38 Pages) AD

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HMC702LP6CE

v10.0812

14 GHz 16-BIT FRACTIONAL-N PLL

the frequency step size while ramping is controlled by rampstep, (Reg15h table 26).

Frequency Step Size Δƒstep = rampstep • fxtal / 2

•

where r is the value of the reference divider (rfp_div_ratio in table 9)

clearing or setting ramp_startdir_dn, (Reg14h<4> table 25), sets the initial ramp direction to be increasing or

decreasing in frequency respectively. Setting ramp_singledir (Reg14h<7> table 25), restricts the direction of the

sweep to the initial sweep direction only.

the sweeper timebase Tref is the period of the divided reference, fPFD, at the phase detector Tref

the total number of ramp steps taken in a single sweep is given by ramp_steps_number in reg16h table 27.

the total time to ramp from fo to ff is given by Tramp = Tref • ramp_steps_number

the final ramp frequency, ff, is given by ƒƒ = ƒi + Δƒstep • ramp_steps_number

Sweeper action at the end of sweep depends upon the mode of the sweep:

a. With both ramp_singledir and ramp_repeat_en disabled, at the end of the ramp time, Tramp,

the sweeper will dwell at the final frequency ff, until a new trigger is received. the next trigger will

reverse the current sequence, starting from ff, and stepping back to fo. odd triggers will ramp in the

same direction as the initial ramp, even triggers will ramp in the opposite direction.

b. with ramp_singledir enabled and ramp_repeat_en disabled, at the end of the ramp time, Tramp,

the sweeper will dwell at the final frequency ff, until a new trigger is received. the second trigger

will hop the synthesizer back to the initial frequency, fo. the third trigger will restart the sweep from

fo. Hence all odd numbered triggers will start a new ramp in the same direction as the initial ramp,

even numbered triggers will hop the synthesizer from the current frequency to fo , where it will wait

for a trigger to start a sweep.

Ramp Busy

in all types of sweeps ramp_busy will indicate an active sweep and will stay high between the 1st and nth ramp step.

ramp_busy may be monitored one of two ways. ramp_busy is readable via read only register Reg1Fh<5> table 36.

ramp_busy may also be monitored on GPo2, hardware pin 24, by setting Reg1Bh<3:0> =8h table 32.

Autosweep Mode

the autosweep mode is similar to Figure 16 except that once started, triggers are not required. once enabled, (ramp_

repeat_en=1 Reg14h<3> table 25) the autosweep mode initiates the first trigger, steps n times, one step per ref clock

cycle, and then waits for the programmed dwell period and automatically triggers the ramp in the opposite direction.

the sweep process continues alternating sweep directions until disabled. dwell_time (Reg17h table 28) controls the

number of Tref periods to wait at the end of the ramp before automatically retriggering a new sweep.

2-Way Sweeps

if ramp_repeat_en (Reg14h<3> table 25) is cleared, then the ramps are triggered by

a. Writing to ramp_trigg (Reg14h<2> table 25), if bit <2> = 0, or

b. by rising edge ttL signal input on GPo3, if ramp_trig_ext_en is set, and GPo3 is enabled.

all functions are the same in Figure 16 for autosweep or 2-Way triggered sweeps, the only difference is the trigger

source is generated internally for autosweep, and is input via serial port or GPo3 for triggered sweeps. Sweep_busy

will go high at the start of every ramp and stay high until the nth step in the ramp.

Information furnished by Analog Devices is believed to be accurate and reliable. However, no

responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other

rights of third parties that may result from its use. Specifications subject to change without notice. No

license is granted by implication or otherwise under any patent or patent rights of Analog Devices.

Trademarks and registered trademarks are the property of their respective owners.

For price, delivery, and to place orders: Analog Devices, Inc.,

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106

Phone: 781-329-4700 • Order online at www.analog.com

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