L2340
DEVICES INCORPORATED
Digital Synthesizer
OBIQ — Data Input/Output Format
Select
When OBIQ is HIGH, offset binary
format is selected. When OBIQ is
LOW, unsigned format is selected.
OEI — x-coordinate Data Output
Enable
When OEI is LOW, I
15-0
is enabled for
data output. When OEI is HIGH, I
15-0
is placed in a high-impedance state.
OEQ — y-coordinate Data Output
Enable
When OEQ is LOW, Q
15-0
is enabled
for data output. When OEQ is HIGH,
Q
15-0
is placed in a high-impedance
state.
FM, PM — Frequency Modulation,
Phase Modulation Control
FM and PM is the 2-bit Frequency
Modulation/Phase Modulation
Control that determines one of the
four modes shown in Table 2. When
full-scale is exceeded, the accumulator
will roll over correctly allowing
continuous phase accumulation
through 2π radians.
F
IGURE
1
A
.
I
NPUT
F
ORMATS
AM
PH
(RTP = 0)
Fract. Unsigned Mag./Two's Comp.
31 30 29
*±2
0
2
–1
2
–2
2 1 0
2
–29
2
–30
2
–31
Integer Unsigned Magnitude
14 13 12
2
14
2
13
2
12
2 1 0
2
2
2
1
2
0
*±2
0
denotes two's complement sign or highest magnitude bit. Since phase angles are modulo 2π
32
and phase accumulator is modulo 2 , this bit may be regarded as ±π
.
F
IGURE
1
B
.
O
UTPUT
F
ORMATS
I
Integer Unsigned Magnitude (OBIQ = 0)
14 13 12
2
14
2
13
2
12
2 1 0
2
2
2
1
2
0
14 13 12
2
14
2
13
2
12
2 1 0
2
2
2
1
2
0
Q
Offset Binary (OBIQ = 1)
15 14 13
NS 2
14
2
13
2 1 0
2
2
2
1
2
0
15 14 13
NS 2
14
2
13
2 1 0
2
2
2
1
2
0
NS denotes negative sign. (i.e. '1' negates the number)
Special Arithmetic Functions
3
08/16/2000–LDS.2340-E
LOGIC [ LOGIC DEVICES INCORPORATED ]
