MAX1198 Datasheet, PDF (12/22 Pages) Maxim Integrated Products – Dual, 8-Bit, 100Msps, 3.3V, Low-Power ADC with Internal Reference and Parallel Outputs

Dual, 8-Bit, 100Msps, 3.3V, Low-Power ADC
with Internal Reference and Parallel Outputs
INTERNAL
BIAS
S2a
S4a
INA+
C2a
S4c
S1
COM
S5a
C1a
S3a
OUT
INA-
S4b
C2b
OUT
C1b
S2b
INTERNAL
BIAS
INTERNAL
BIAS
S2a
S3b
S5b
COM
COM
S5a
C1a
S3a
HOLD
HOLD
CLK
TRACK
TRACK
INTERNAL
NONOVERLAPPING
CLOCK SIGNALS
S4a
INB+
OUT
C2a
S4c
S1
INB-
S4b
C2b
OUT
MAX1198
C1b
S2b
INTERNAL
BIAS
S3b
S5b
COM
Figure 2. MAX1198 T/H Amplifiers
are closed. The fully differential circuits sample the
input signals onto the two capacitors (C2a and C2b)
through switches S4a and S4b. S2a and S2b set the
common mode for the amplifier input, and open simul-
taneously with S1 sampling the input waveform.
Switches S4a, S4b, S5a, and S5b are then opened
before switches S3a and S3b connect capacitors C1a
and C1b to the output of the amplifier and switch S4c is
closed. The resulting differential voltages are held on
capacitors C2a and C2b. The amplifiers are used to
charge capacitors C1a and C1b to the same values
originally held on C2a and C2b. These values are then
presented to the first-stage quantizers and isolate the
pipelines from the fast-changing inputs. The wide input
bandwidth T/H amplifiers allow the MAX1198 to track
and sample/hold analog inputs of high frequencies
(>Nyquist). Both ADC inputs (INA+, INB+ and INA-,
INB-) can be driven either differentially or single ended.
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