AD9910SLASHPCBZ datasheet(16/60 Pages) AD

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AD9910

Rev. 0 | Page 16 of 60

THEORY OF OPERATION

The AD9910 has four modes of operation:

•

Single tone

•

RAM modulation

•

Digital ramp modulation

•

Parallel data port modulation

The modes relate to the data source used to supply the DDS

with its signal control parameters: frequency, phase, or ampli-

tude. The partitioning of the data into different combinations

of frequency, phase, and amplitude is handled automatically

based on the mode and/or specific control bits.

In single tone mode, the DDS signal control parameters come

directly from the programming registers associated with the

serial I/O port. In RAM modulation mode, the DDS signal

control parameters are stored in the internal RAM and played

back upon command. In digital ramp modulation mode, the

DDS signal control parameters are delivered by a digital ramp

generator. In parallel data port modulation mode, the DDS

signal control parameters are driven directly into the parallel port.

The various modulation modes generally operate on only one of

the DDS signal control parameters (two in the case of the polar

modulation format). The unmodulated DDS signal control

parameters are stored in their appropriate programming

registers and automatically route to the DDS based on the

selected mode.

A separate output shift keying (OSK) function is also available.

This function employs a separate digital linear ramp generator

that only affects the amplitude parameter of the DDS. The OSK

function has priority over the other data sources that can drive

the DDS amplitude parameter. As such, no other data source

can drive the DDS amplitude when the OSK function is enabled.

Although the various modes (including the OSK function) are

described independently, they can be enabled simultaneously.

This provides an unprecedented level of flexibility for generating

complex modulation schemes. However, to avoid multiple data

sources from driving the same DDS signal control parameter,

the device has a built-in priority protocol (see Table 5 in the

Mode Priority section).

SINGLE TONE MODE

In single tone mode, the DDS signal control parameters are

supplied directly from the programming registers. A profile is

an independent register that contains the DDS signal control

parameters. Eight profile registers are available.

Each profile is independently accessible. Use the three external

profile pins (PROFILE<2:0>) to select the desired profile. A

change in the state of the profile pins with the next rising edge

on SYNC_CLK updates the DDS with the parameters specified

by the selected profile.

PARALLEL

INPUT

PDCLK

SCLK

SDIO

I/O_RESET

PROFILE

I/O_UPDATE

RAM

POWER

DOWN

CONTROL

DAC_RSET

IOUT

TxENABLE

DAC FSC

OSK

INVERSE

SINC

FILTER

CLOCK

AMPLITUDE (A)

FREQUENCY (ω)

PHASE (θ)

DIGITAL

RAMP

GENERATOR

DAC FSC

MULTICHIP

SYNCHRONIZATION

SYSCLK

PLL

÷2

REF_CLK

REFCLK_OUT

XTAL_SEL

PARALLEL DATA

TIMING AND

CONTROL

AD9910

PROGRAMMING

REGISTERS

OUTPUT

SHIFT

KEYING

DATA

ROUTE

AND

PARTITION

CONTROL

INTERNAL CLOCK TIMING

AND CONTROL

Acos (ωt+θ)

Asin (ωt+θ)

AUX

DAC

8-BIT

DAC

14-BIT

DDS

RAM_SWP_OVR

DRCTL

DRHOLD

DROVER

Figure 22. Single Tone Mode

AD9910/PCBZ Datasheet(PDF) 16 Page - Analog Devices

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