Datasheet
AD9122
Rev. B | Page 27 of 60
Register
Name
Address
(Hex) Bits Name Description Default
Datapath
Control
0x1B 7 Bypass premod 1 = bypass the f
S
/2 premodulator. 1
6 Bypass sinc
−1
1 = bypass the inverse sinc filter. 1
5 Bypass NCO 1 = bypass the NCO. 1
3 NCO gain
0 = no gain scaling is applied to the NCO input to the
internal digital modulator (default).
0
1 = gain scaling of 0.5 is applied to the NCO input to the
internal digital modulator. Gain scaling can eliminate satu-
ration of the modulator output for some combinations of
data inputs and NCO signals.
2
Bypass phase
compensation
and dc offset
1 = bypass phase compensation and dc offset. 1
1 Select sideband 0 = the modulator outputs the high-side image. 0
1 = the modulator outputs the low-side image. The image is
spectrally inverted compared to the input data.
0 Send I data to Q data
1 = ignore Q data from the interface and disable the clocks
to the Q datapath. Send I data to both the I and Q DACs.
0
HB1 Control 0x1C [2:1] HB1[1:0] Modulation mode for I Side Half-Band Filter 1. 00
00 = input signal not modulated; filter pass band is from
−0.4 to +0.4 of f
IN1
.
01 = input signal not modulated; filter pass band is from
0.1 to 0.9 of f
IN1
.
10 = input signal modulated by f
IN1
; filter pass band is from
0.6 to 1.4 of f
IN1
.
11 = input signal modulated by f
IN1
; filter pass band is from
1.1 to 1.9 of f
IN1
.
0 Bypass HB1 1 = bypass the first-stage interpolation filter. 0
HB2 Control 0x1D [6:1] HB2[5:0] Modulation mode for I Side Half-Band Filter 2. 000000
000000 = input signal not modulated; filter pass band is
from −0.25 to +0.25 of f
IN2
.
001001 = input signal not modulated; filter pass band is
from 0.0 to 0.5 of f
IN2
.
010010 = input signal not modulated; filter pass band is
from 0.25 to 0.75 of f
IN2
.
011011 = input signal not modulated; filter pass band is
from 0.5 to 1.0 of f
IN2
.
100100 = input signal modulated by f
IN2
; filter pass band is
from 0.75 to 1.25 of f
IN2
.
101101 = input signal modulated by f
IN2
; filter pass band is
from 1.0 to 1.5 of f
IN2
.
110110 = input signal modulated by f
IN2
; filter pass band is
from 1.25 to 1.75 of f
IN2
.
111111 = input signal modulated by f
IN2
; filter pass band is
from 1.5 to 2.0 of f
IN2
.
0 Bypass HB2 1 = bypass the second-stage interpolation filter. 0