Max2055, Detailed description, Applications information – Rainbow Electronics MAX2055 User Manual
Page 10: Digitally controlled attenuator, Single-ended-to-differential amplifier
MAX2055
Detailed Description
The MAX2055 is a high-dynamic-range, digitally con-
trolled, variable-gain differential ADC driver/amplifier
(DVGA) for use in applications from 30MHz to 300MHz.
The amplifier is designed for 50
Ω single-ended input
and 50
Ω differential output systems.
The MAX2055 integrates a digital attenuator with a
23dB selectable attenuation range and a high-linearity,
single-ended-to-differential output amplifier. The attenu-
ator is digitally controlled through five logic lines:
B0–B4. The on-chip attenuator provides up to 23dB of
attenuation with ±0.2dB accuracy. The single-ended
input to differential output amplifier utilizes negative
feedback to achieve high gain and linearity over a wide
bandwidth.
Applications Information
Digitally Controlled Attenuator
The digital attenuator is controlled through five logic
lines: B0, B1, B2, B3, and B4. Table 3 lists the attenua-
tion settings. The input and output of this attenuator
require external DC blocking capacitors. The attenua-
tor’s insertion loss is approximately 2dB, when the con-
trol bits are set to 0dB (B0 = B1 = B2 = B3 = B4 = 0).
Single-Ended-to-Differential Amplifier
The MAX2055 integrates a single-ended-to-differential
amplifier with a nominal gain of 22dB in a negative
Digitally Controlled, Variable-Gain, Differential
ADC Driver/Amplifier
10
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20
19
18
17
16
15
14
13
1
2
3
4
5
6
7
8
GND
ATTN
OUT
GND
I
SET
R
1
B4
GND
RF_IN
RF_IN
V
CC
V
CC
C
C
AMP
IN
L
E
C
BP
B0
B1
B2
B3
12
11
1
9
10
I
BIAS
RF_OUT+
RF_OUT
RF_OUT-
CONTROL
INPUTS
ATTENUATION
LOGIC
CONTROL
V
CC
V
CC
MAX2055
C
12
C
11
T
2
C
10
V
CC
C
9
L
5
L
4
C
8
C
5
C4
C
6
C
3
C
1
C
2
1
T
1
L
1
L
2
L
3
R
7
Figure 1. Typical Application Circuit