
STEL-1376
2
BLOCK DIAGRAM
FEATURES
s HIGH CLOCK FREQUENCY
- 80 MHz MAXIMUM OVER
COMMERCIAL OPERATING CONDITIONS
s HIGH OUTPUT BANDWIDTH
- UP TO 35 MHz OUTPUT FREQUENCY
s HIGH FREQUENCY RESOLUTION WITH
DECIMAL FREQUENCY STEPS
- PRECISELY 0.1 Hz @ 80 MHz CLOCK
s VERY HIGH SPEED FREQUENCY
HOPPING OR MODULATION
- MAX. UPDATE SPEED 250 NANOSECS.
s PRECISION PHASE MODULATION
- 3 bits FOR 8ARY PSK
s HIGH SPECTRAL PURITY
–60 dBc SPURIOUS TYPICAL
s PARALLEL OR BYTE-WIDE CONTROL
INPUTS
s 3.35" BY 1.5" BY 0.35"
APPLICATIONS
s PRECISION SYNTHESIZERS
s INSTRUMENTATION
s CARRIER GENERATION
The STEL-1376 is a complete Decimal/BCD Direct
Digital Frequency Synthesizer in a single DIL package
measuring only 3.35 x 1.5". The STEL-1376 makes it
possible to use DDS technology in applications
requiring precise decimal frequency steps. The STEL-
1376 is a printed circuit unit using the STEL-1176
Decimal/BCD Numerically Controlled Oscillator
(NCO) chip driving a high-speed 10-bit DAC (Sony
CX20201A-1) to generate an analog output signal.
Surface mount technology (SMT) components are
used throughout. The device is guaranteed to operate
at clock frequencies up to 80 MHz over the
temperature range of 0 to 50
°C, giving an output
frequency range of 0 to over 35 MHz, with a frequency
resolution of precisely 0.1 Hz at a clock frequency of 80
MHz. The device is programmed in 1-2-4-8 BCD
format, so that 4 bits are used to program each decade.
A divided clock output at 5 or 10 MHz is provided to
facilitate locking the clock to a standard frequency
reference. In addition, the device features phase
modulation capabilities at extremely high modulation
rates, up to 25% of the clock frequency. The phase
modulation capability allows binary, quaternary or
8ary PSK to be implemented. For more detailed
information on the STEL-1176 NCO please refer to the
STEL-1176 data sheet. For more information on the
DAC please refer to the Sony CX20201A-1 data sheet.
The output frequency is directly related to the clock
frequency by the following:
fc x -Phase
fo=
8 x 108
where:
fo is the frequency of the output signal
and:
fc is the clock frequency.
STEL-1176
DNCO
CMOS-ECL
LEV EL
SHIFTERS
10-BIT
DA C
CLOCK
ECL/CMOS LEV EL SHIFTER
ANALOG
OUT
DA TA 34-0
A DDR 2-0
WRSTB
FRLD
10
PHLD
RESET
VREF
CSEL
CIN
LDCLK
REFCLK
PHA SE 2-0
CLKSEL