Euvis

Product Catalog

DS875 – Phase Modulated Direct Digital Synthesizer
with Phase Modulation PortVC C

RSTLatch

Latch

2

O U T_P /N

C kP 7
C kP 6111111M D SL

Latches

SE L1

D ecoder11

AV S
C kP 8Latches

S TR B _P/N

2

Pipeline
Clock

Ck P 1

2Sw itch

11LatchCk P 811Sine ROM

Latches30

12Adders

Accumulator30

V i[0:29]

VC C OP i[0:10]
22

S yncI_P/N
C K _P/N

S yncO _P/N

D ivide by 8

2C lock D istribution

GNDVEEVE ED

VEE A

KEY FEATURES•••••••••••••••••

30-bit frequency tuning word
11-bit phase modulation inputs synchronized with frequency word inputs
12-bit ROM phase address resolution
On chip DAC with 11 bit linearity
Clock rate up to 2.8 GHz
Analog outputs selectable between Normal-Hold format and Return-to-Zero format.
Sine wave generation up to 1.4 GHz 1st Nyquist band for Normal-Hold mode or 4.2 GHz
3rd Nyquist band for Return-to-Zero mode.
Broadband worst SFDR > 50 dBc (DC to 1.4-GHz 1st Nyquist Bandwidth) at a 2.8 GHz
clock rate
Complementary analog waveform outputs with 50 Ω back terminations
SyncI_P/N synchronizes multiple chip applications
SyncO_P/N 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 and phase word of DAC outputs
Wide data loading window allow DS875 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
4 W power consumption with a single -5V power supply
64-pin QFN package

Description
The DS875 is a high-speed Direct Digital Synthesizer (DDS) with phase modulation input port.
It has a frequency tuning resolution of 30 bits and phase modulation input of 11 bits. The internal Euvis Inc. 685 Cochran Street, Suite 160, Simi Valley, CA 93065
Email: sales@euvis.com Web: www.euvis.com Tel.: (805) 583-9888

6EuvisProduct Catalog

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 1stNyquist band ) and Return-to-Zero mode (for the 1st, 2nd and 3rd Nyquist band) operation.

Sine waves can be generated up to 1st Nyquist band near 1.4 GHz (at a 2.8-GHz clock rate) with
Normal-Hold mode of DAC or up to 3rd Nyquist band around 4 GHz with Return-to-Zero modeof 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
frequency of output waveforms can be controlled by the thirty frequency control bits, Vi[0:29].
The phase of output waveforms can be modulated by the 11-bit Pi[0:10] phase modulation
inputs. The DS875 accepts either differential clock inputs or a single-ended clock input andfeatures 50-Ω on-chip back terminations to ground. Both the frequency word and phase 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 SyncO_P/N ready to accept frequency word and strobe inputs. The
synchronous Strobe inputs are latched by internal generated divide-by-8 clocks which were also
sent to the output pins SyncO_P/N. SyncO_P/N. can be used as a reference to synchronize thefrequency word, phase word and strobe signal input timing alignment to the internal divide-by-8
clock to latch all input data properly. The Reset is asynchronous to minimize clock latencies ofeffectiveness on the analog outputs. The internal timing was optimized to avoid clock slipping
during frequency word and/or phase word transition or after reset. The analog outputs of DAC
can be selected between Normal Hold mode (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 the 3rd 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

7