Datasheet

MAX2027
IF Digitally Controlled Variable-Gain Amplifier
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Detailed Description
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
±0.05dB state-to-state accuracy. The fixed-gain amplifi-
er utilizes negative feedback to achieve high stability,
gain, linearity, and wide bandwidth.
Applications Information
Input and Output Matching
The MAX2027 incorporates on-chip input and output
matching for operation below 250MHz. Use a DC-block-
ing capacitor value of 1000pF for pins 3, 12, and 18 (see
Figure 1). For operation above 250MHz, external match-
ing improves performance. Table 1 and Table 2 provide
recommended components for device operation.
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. This attenua-
tor insertion loss is 2dB when the attenuator is set to
0dB (B0 = B1 = B2 = B3 = B4 = 0).
Pin Description
PIN NAME FUNCTION
1, 2, 11 V
CC
Power Supply. Bypass to GND with capacitors as close to the pin as possible as shown in the typical
application circuit (Figure 1).
3 RF_IN
Signal Input. See the typical application circuit for recommended component values. Requires an
external DC-blocking capacitor.
4, 5, 16, 17,
19, 20, EP
GND
Ground. Use low-inductance layout techniques on PC board. Solder the exposed pad evenly to the
board ground plane.
6–10 B4–B0 Gain-Control Bits. See Table 3 for gain setting.
12 RF_OUT
Signal Output. Requires an external pullup choke inductor (52mA typical current) to V
CC
along with a
DC-blocking capacitor (Figure 1).
13 I
SET
Connect an 825Ω resistor from I
SET
to GND.
14 I
BIAS
Amplifier Bias. Connect to AMP
IN
(pin 15) through a choke inductor (0.3mA typ).
15 AMP
IN
Amplifier Input. Requires a DC-coupling capacitor to allow biasing.
18
ATTN
OUT
Attenuator Output. Requires an external DC-blocking capacitor.
COMPONENT VALUE SIZE
C1, C3, C4 1000pF 0603
C2, C5 100pF 0603
C6, C7 0.1µF 0603
C10 0.047µF 0603
R1 825Ω ±1% 0603
R2–R6 47kΩ 0603
L1 330nH 0805
L2 680nH 1008
Table 1. Suggested Components of
Typical Application Circuit
FREQUENCY
COMPONENT
VALUE SIZE
L3, L4 11nH 0603
300MHz
C8, C9 6.8pF 0603
L3, L4 8.7nH 0603
400MHz
C8, C9 5pF 0603
Table 2. Suggested Matching
Components