AD9911SLASHPCB datasheet(25/44 Pages) AD

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AD9911

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sweep is then complete and the output held constant in

frequency. See Figure 43 for the linear sweep circuitry.

Figure 45 depicts a frequency sweep with no-dwell mode

disabled. In this mode, the output follows the state of the profile

pin. A phase or amplitude sweep works in the same manner

with fewer bits.

LINEAR SWEEP NO DWELL MODE

To enable linear sweep no dwell mode, set CFR <15>. The rising

sweep is started by setting the profile input pin to 1. The

frequency, phase or amplitude continues to sweep up at the rate

set by the rising sweep ramp rate and the resolution set by the

rising delta tuning word, until it reaches E0. The output then

reverts to the S0 and stalls until high is detected on the

profile pin.

Figure 44 demonstrates the no-dwell mode. The points labeled

A indicate where a rising edge is detected on the profile pin.

Points labeled B indicate at which points where the AD9911 has

determined that the output has reached E0 and reverts to S0.

The falling ramp rate register and the falling delta word are

unused in this mode.

RATE TIME

LOAD CONTROL

LOGIC

LIMIT LOGIC TO

KEEP SWEEP BETWEEN

S0 AND E0

RAMP RATE TIMER:

8-BIT LOADABLE DOWN COUNTER

ACCUMULATOR RESET

LOGIC

MUX

PROFILE PIN

MUX

FDW

RDW

FSRR

RSRR

PROFILE PIN

Z–1

CTW1

SWEEP ACCUMULATOR

SWEEP ADDER

CTW0

Figure 43. Linear Sweep Block Circuitry

FTW0

SINGLE–TONE

MODE

FTW1

fOUT

TIME

PS<1> = 1 PS<1> = 0

PS<1> = 0

PS<1> = 1

PS<1> = 0

Figure 44. Linear Sweep Mode Enabled—No Dwell Bit Set

AD9911/PCB Datasheet(PDF) 25 Page - Analog Devices

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