MAX1180ECM-TD Maxim Integrated, MAX1180ECM-TD Datasheet - Page 16

• Manufacturer Part Number: MAX1180ECM-TD
• Description: Analog to Digital Converters - ADC
• Manufacturer: Maxim Integrated

Specifications of MAX1180ECM-TD

• Number Of Channels: 2
• Architecture: Pipeline
• Conversion Rate: 105 MSPs
• Resolution: 10 bit
• Input Type: Single-Ended/Differential
• Snr: 59 dB
• Interface Type: Parallel
• Operating Supply Voltage: 3.3 V
• Maximum Operating Temperature: + 85 C
• Package / Case: TQFP EP
• Maximum Power Dissipation: 511 mW
• Minimum Operating Temperature: - 40 C
• Number Of Converters: 2
• Voltage Reference: Internal, External

Dual 10-Bit, 105Msps, 3.3V, Low-Power ADC
with Internal Reference and Parallel Outputs
Figure 6. Transformer-Coupled Input Drive
Figure 7 shows an AC-coupled, single-ended applica-
tion. Amplifiers, like the MAX4108, provide high-speed,
high bandwidth, low-noise, and low distortion to main-
tain the integrity of the input signal.
The most frequently used modulation technique for dig-
ital communications application is the Quadrature
Amplitude Modulation (QAM). QAMs are typically found
in spread-spectrum based systems. A QAM signal rep-
resents a carrier frequency modulated in both ampli-
tude and phase. At the transmitter, modulating the
baseband signal with quadrature outputs, a local oscil-
lator followed by subsequent up-conversion can gener-
ate the QAM signal. The result is an in-phase (I) and a
16
V
V
IN
IN
______________________________________________________________________________________
Typical QAM Demodulation Application
0.1µF
0.1µF
Single-Ended AC-Coupled Input Signal
N.C.
N.C.
MINI-CIRCUITS
MINI-CIRCUITS
3
3
1
1
2
2
TT1–6
TT1–6
T1
T1
6
5
4
6
5
4
2.2µF
2.2µF
25Ω
25Ω
25Ω
25Ω
0.1µF
0.1µF
22pF
22pF
22pF
22pF
INA+
COM
INA-
INB+
INB-
MAX1180
quadrature (Q) carrier component, where the Q compo-
nent is 90 degrees phase-shifted with respect to the in-
phase component. At the receiver, the QAM signal is
divided down into its I and Q components, essentially
representing the modulation process reversed. Figure 8
displays the demodulation process performed in the
analog domain, using the dual-matched, 3V, 10-bit
ADCs, MAX1180 and the MAX2451 quadrature demod-
ulators, to recover and digitize the I and Q baseband
signals. Before being digitized by the MAX1180, the
mixed-down signal components may be filtered by
matched analog filters, such as Nyquist or Pulse-
Shaping filters which remove any unwanted images
from the mixing process, enhances the overall signal-
to-noise (SNR) performance, and minimizes intersym-
bol interference.
The MAX1180 requires high-speed board layout design
techniques. Locate all bypass capacitors as close to
the device as possible, preferably on the same side as
the ADC, using surface-mount devices for minimum
inductance. Bypass V
two parallel 0.1µF ceramic capacitors and a 2.2µF
bipolar capacitor to GND. Follow the same rules to
bypass the digital supply (OV
boards with separate ground and power planes, pro-
duce the highest level of signal integrity. Consider the
use of a split ground plane arranged to match the
physical location of the analog ground (GND) and the
digital output driver ground (OGND) on the ADCs pack-
age. The two ground planes should be joined at a sin-
gle point, such that the noisy digital ground currents do
not interfere with the analog ground plane. The ideal
location of this connection can be determined experi-
mentally at a point along the gap between the two
ground planes, which produces optimum results. Make
this connection with a low-value, surface-mount resistor
(1Ω to 5Ω), a ferrite bead, or a direct short.
Alternatively, all ground pins could share the same
ground plane, if the ground plane is sufficiently isolated
from any noisy, digital systems ground plane (e.g.,
downstream output buffer or DSP ground plane). Route
high-speed digital signal traces away from the sensitive
analog traces of either channel. Make sure to isolate
the analog input lines to each respective converter to
minimize channel-to-channel crosstalk. Keep all signal
lines short and free of 90 degree turns.
Grounding, Bypassing,
DD
, REFP, REFN, and COM with
and Board Layout
DD
) to OGND. Multilayer