Euvis

Product Catalog

DS875A – Direct Digital Synthesizer with Phase andAmplitude Modulation Ports
VCC

AVCCP

RST
224CkP8Ai[0:7]
SyncI_P/N

Latch

Decoder

CkP8CkP788Latches

Pi[0:7]88Latches

8Latches

CkP7

Latch

CkP8

AOUT_P/N2

BOUT_P/N

Switch11Latch2Latches2

STRB_P/N

Pipeline
Clock

CkP1

11Sine ROM

LatchesVi[0:23]

12Adders

Accumulator

24Digital
Controlled
PowerDivider

11AVS

8MDSL
22SyncOP

Divide by 82CKPClock Distribution

GNDVEEVEED

VEEA

KEY FEATURES• Integrated FM, PM and AM functions in one chip suitable for direct polar modulation orQAM applications• 24-bit frequency tuning word
• 8-bit phase modulation inputs synchronized with frequency/amplitude word inputs• 8-bit amplitude modulation inputs synchronized with frequency/phase word inputs• 12-bit ROM phase address resolution• On chip DAC with 11 bit linearity• Clock rate up to 2.5 GHz• Analog outputs selectable between Normal-Hold format and Return-to-Zero format.
• Sine wave generation up to 1.2 GHz 1st Nyquist band for Normal-Hold mode or 3.7 GHz
3rd Nyquist band for Return-to-Zero mode.
• Broadband worst SFDR > 50 dBc (DC to 1.2-GHz 1st Nyquist Bandwidth) at a 2.5 GHzclock rate
• Complementary analog waveform outputs with 50 Ω back terminations• SyncI_P/N synchronizes multiple chip applications• SyncOP provides reference for data loading and synchronizes STROBE signals.
• LVTTL/CMOS frequency word and phase modulation word digital inputs• Asynchronous Reset (RST) pin to initiate starting phase state set by phase bit inputs• Strobe inputs (STRB_P/N) to update the frequency word, phase word and amplitude wordof DAC outputs Euvis Inc. 685 Cochran Street, Suite 160, Simi Valley, CA 93065
Email: sales@euvis.com Web: www.euvis.com Tel.: (805) 583-9888

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Euvis

Product Catalog• Wide data loading window allow DS875A to be controlled by memory, micro-controller,
FPGA or DSP chips to update frequency word and/or phase word as fast as 8 clock cycles
without clock slipping or glitches during frequency or phase transition• 3.9 W power consumption with a single -5V power supply• 64-pin QFN package

Description
The DS875A is a high-speed Direct Digital Synthesizer (DDS) with both phase modulation andamplitude modulation input ports designed for direct polar modulation or QAM applications. It
has frequency tuning resolution of 24 bits, phase modulation input of 8-bits and amplitude
modulation input of 8 bits. The internal ROM has phase resolution of 12-bit and the internal
DAC has amplitude resolution of 11 bits. The analog outputs of DAC can be selected

between Normal-Hold mode (for the 1st Nyquist band ) and Return-to-Zero mode (for the1st, 2nd and 3rd Nyquist band) operation. Sine waves can be generated up to 1st Nyquist bandnear 1.2 GHz (at a 2.5-GHz clock rate) with Normal-Hold mode of DAC or up to 3rd Nyquist
band around 3.7 GHz with Return-to-Zero mode of DAC. The initial phase can be reset to any
degree, determined by phase bit inputs, to start with. The chip has a pair of complementary
analog outputs with 50-Ω back terminations. The DAC analog output was digitally controlled to256 levels by 8-bit digital inputs. The frequency of output waveforms can be controlled by the 24
frequency control bits, Vi[0:23]. The phase of output waveforms can be modulated by the 8-bit
Pi[0:7] phase modulation inputs and the analog outputs can be modulated by the 8-bit Ai[0:7].
Amplitude modulation inputs. The DS875A accepts a single-ended clock input and features 50Ω on-chip back terminations to ground. Both the frequency word, phase word and amplitude
word inputs accept LVTTL/CMOS input levels. Differential synchronization input SyncI_P/Nprovides synchronization for multiple chip applications and start each chip with the same phase ofsynchronization outputs SyncOP ready to accept frequency word, phase word, amplitude wordand strobe inputs. The synchronous Strobe inputs are latched by internal generated divide-by-8
clocks which were also sent to the output pin SyncOP. SyncOP. can be used as a reference tosynchronize the frequency word, phase word, amplitude word and strobe signal input timingalignment to the internal divide-by-8 clock to latch all the inputs properly. The Reset isasynchronous to minimize clock latencies of effectiveness on the analog outputs. The internaltiming was optimized to avoid clock slipping during frequency word and/or phase, amplitude
word transition or after reset. The analog outputs of DAC can be selected between Normal-Holdmode (for the 1st Nyquist band ) or Return-to-Zero mode (for the 1st, 2nd and 3rd Nyquist band)
operation. Combining with selectable filters, effectively ultra-broadband signals from DC to the3rd Nyquist band can be generated. Only a single -5V power supply is required.

 Euvis Inc. 685 Cochran Street, Suite 160, Simi Valley, CA 93065
Email: sales@euvis.com Web: www.euvis.com Tel.: (805) 583-9888

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