Rainbow Electronics MAX1011 - Manual (Page 6)

MAX1011
amplifier inputs is internally biased to a 2.35V reference
through a 20k
Ω
resistor, eliminating external DC bias
circuits. A series 0.1µF capacitor is required at the
amplifier input for AC-coupled signals.
When operating with AC-coupled inputs, the input
amplifier’s DC offset voltage is nulled to within ±1/2LSB
by an on-chip, offset-correction amplifier. An external
compensation capacitor is required to set the dominant
pole of the offset-correction amplifier’s frequency
response (Figures 2 and 3). The compensation capaci-
tor will determine the low-frequency corner of the ana-
log input response according to the following formula:
f c = 1 / (0.1 x C)
where C is the value of the compensation capacitor in
µF, and f
c is the corner frequency in Hz.
Low-Power, 90Msps, 6-Bit ADC
6 _______________________________________________________________________________________
6 BITS
DATA
BUFFER DIGITAL
DEMODULATOR
OR
DSP
6
DCLK
TANK
MAX1011
LO
RF
Figure 1. IF Sampling Receiver
Figure 2. Single-Ended AC-Coupled Input Figure 3. Differential AC-Coupled Input
MAX1011
INPUT
AMP
20k
2.35V INTERNAL REFERENCE
20k
IN+
OCC+ OCC-
IN-
0.1 µ F
0.22 µ F
V SOURCE
0.1 µ F
OFFSET
CORREC-
TION
MAX1011
INPUT
AMP
20k
2.35V INTERNAL REFERENCE
20k
IN+
OCC+ OCC-
IN-
0.1 µ F
0.1 µ F
V
SOURCE
OFFSET
CORREC-
TION
0.22 µ F