Detailed Description
The MAX105 is a dual, +5V, 6-bit, 800Msps flash ana-
log-to-digital converter (ADC), designed for high-
speed, high-bandwidth I&Q digitizing. Each ADC
(Figure 1) employs a fully differential, wide bandwidth
input stage, 6-bit quantizers and a unique encoding
scheme to limit metastable states to typically one error
per 10
16
clock cycles, with no error exceeding a maxi-
mum of 1LSB. An integrated 6:12 output demultiplexer
simplifies interfacing to the part by reducing the output
data rate to one-half the sampling clock rate. The
MAX105 outputs data in LVDS two’s complement for-
mat.
When clocked at 800Msps, the MAX105 provides a typ-
ical signal-to-noise plus distortion (SINAD) of 36.4dB
with a 200MHz input tone. The analog input of the
MAX105 is designed for differential or single-ended use
with a ±400mV full-scale input range. In addition, the
MAX105 features an on-board +2.5V precision
bandgap reference, which is scaled to meet the analog
input full-scale range.
Principle of Operation
The MAX105 employs a flash or parallel architecture.
The key to this high-speed flash architecture is the use
of an innovative, high-performance comparator design.
Each quantizer and downstream logic translates the
comparator outputs into 6-bit, parallel codes in two’s
complement format and passes them on to the internal
6:12 demultiplexer. The demultiplexer enables the
ADCs to provide their output data at half the sampling
speed on primary and auxiliary ports. LVDS data is
available at speeds of up to 400MHz per output port.
Input Amplifier Circuits
As with all ADCs, if the input waveform is changing
rapidly during conversion, effective number of bits
(ENOB), signal-to-noise plus distortion (SINAD), and
MAX105
Dual, 6-Bit, 800Msps ADC with On-Chip,
Wideband Input Amplifier
______________________________________________________________________________________ 11
PIN NAME FUNCTION
62 P2I+ Primary Output Data Bit 2, I-Channel
63 A2I- Complementary Auxiliary Output Data Bit 2, I-Channel
64 A2I+ Auxiliary Output Data Bit 2, I-Channel
65, 72 OV
CC
I
I-Channel Outputs, Digital Supply. Supplies I-channel output drivers and DREADY circuit. Bypass to
OGND with 0.01µF in parallel with 47pF for proper operation.
66, 71 OGNDI
I-Channel Outputs, Digital Ground. Connect to designated digital ground (OGND) on PC board
for proper operation.
67 P3I- Complementary Primary Output Data Bit 3, I-Channel
68 P3I+ Primary Output Data Bit 3, I-Channel
69 A3I- Complementary Auxiliary Output Data Bit 3, I-Channel
70 A3I+ Auxiliary Output Data Bit 3, I-Channel
73 P4I- Complementary Primary Output Data Bit 4, I-Channel
74 P4I+ Primary Output Data Bit 4, I-Channel
75 A4I- Complementary Auxiliary Output Data Bit 4, I-Channel
76 A4I+ Auxiliary Output Data Bit 4, I-Channel
77 P5I- Complementary Primary Output Data Bit 5, I-Channel
78 P5I+ Primary Output Data Bit 5, I-Channel
79 A5I- Complementary Auxiliary Output Data Bit 5, I-Channel
80 A5I+ Auxiliary Output Data Bit 5, I-Channel
Pin Description (continued)
(32 páginas)
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