MAX2027 Maxim Integrated Products, MAX2027 Datasheet - Page 8

• Manufacturer Part Number: MAX2027
• Description: MAX2027 if Digitally Controlled Variable-gain Amplifier
• Manufacturer: Maxim Integrated Products

The MAX2027 is a high-performance, digitally con-
trolled variable-gain amplifier for use in applications
from 50MHz to 400MHz.
The MAX2027 incorporates a digital attenuator with a
23dB selectable attenuation range followed by a fixed-
gain, high-linearity amplifier. The attenuator is digitally
controlled through five logic lines: B0–B4. This on-chip
attenuator provides up to 23dB of attenuation with
±0.2dB accuracy. The fixed-gain amplifier utilizes neg-
ative feedback to achieve high stability, gain, linearity,
and wide bandwidth.
The MAX2027 incorporates on-chip input and output
matching for operation below 150MHz. Use a DC-block-
ing capacitor value of 1000pF for pins 3, 12, and 18 (see
Figure 1). For operation above 150MHz, external match-
ing improves performance. Table 1 and Table 2 provide
recommended components for device operation.
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. This attenua-
tor insertion loss is 2dB when the attenuator is set to
0dB (B0 = B1 = B2 = B3 = B4 = 0).
IF Digitally Controlled Variable-Gain Amplifier
8
4, 5, 16, 17,
19, 20, EP
1, 2, 11
_______________________________________________________________________________________
6–10
PIN
12
13
14
15
18
3
ATTN
Applications Information
RF_OUT
Digitally Controlled Attenuator
NAME
B4–B0
AMP
RF_IN
GND
I
V
I
BIAS
SET
CC
OUT
IN
Input and Output Matching
Detailed Description
Power Supply. Bypass to GND with capacitors as close to the pin as possible as shown in the typical
application circuit (Figure 1).
Signal Input. See the typical application circuit for recommended component values. Requires an
external DC-blocking capacitor.
Ground. Use low-inductance layout techniques on PC board. Solder the exposed pad evenly to the
board ground plane.
Gain-Control Bits. See Table 3 for gain setting.
Signal Output. Requires an external pullup choke inductor (52mA typical current) to V
DC-blocking capacitor (Figure 1).
Connect an 825Ω resistor from I
Amplifier Bias. Connect to AMP
Amplifier Input. Requires a DC-coupling capacitor to allow biasing.
Attenuator Output. Requires an external DC-blocking capacitor.
IN
SET
(pin 15) through a choke inductor (0.3mA typ).
to GND.
Table 1. Suggested Components of
Typical Application Circuit
Table 2. Suggested Matching
Components
FREQUENCY
C1, C3, C4, C6, C7, C10
200MHz
250MHz
300MHz
400MHz
FUNCTION
COMPONENT
C2, C5
R2–R6
R1
L1
L2
COMPONENT
C8, C9
C8, C9
C8, C9
C8, C9
L3, L4
L3, L4
L3, L4
L3, L4
825Ω ±1%
VALUE
1000pF
330nH
680nH
Pin Description
100pF
47kΩ
VALUE
18nH
15nH
11nH
10nH
8pF
8pF
7pF
5pF
CC
along with a
SIZE
0603
0603
0603
0603
0805
1008
SIZE
0603
0603
0603
0603
0603
0603
0603
0603