MAX3524 Datasheet, PDF (5/7 Pages) Maxim Integrated Products – Low-Noise, High-Linearity Broadband Amplifier

Low-Noise, High-Linearity
Broadband Amplifier
Detailed Description
The MAX3524 is a broadband amplifier with a single-
ended input and differential outputs, including an oper-
ational amplifier that can be used to control an external
attenuator circuit. Figure 1 is the MAX3524 EV kit
schematic.
Low-Noise Amplifier
The low-noise amplifier operates from 44MHz to
880MHz and is designed specifically for cable TV and
cable modem applications. The LNA provides 15dB of
insertion voltage gain (see Figure 2) when driving a
3kΩ load. At 300MHz, the noise figure is 4.2dB, IIP2
and IIP3 are 42dBm and 14dBm, respectively.
Operational Amplifier
The operational amplifier is suitable for interfacing to a
PIN attenuator circuit which is typically employed at the
input of the LNA. The common-mode input range is
0.5V to 3V and the output voltage swing is 0.5V to V_CC -
0.5V while sinking or sourcing 20mA. Input bias current
and input offset voltage are 1µA and 1mV, respectively.
The open-loop voltage gain is greater than 10,000. The
gain bandwidth product is greater than 1MHz for a
closed-loop voltage gain of one.
C10
RF INPUT ^0.1µF
TO
C11 _ATTENUATOR
0.1µF
R1
13.3Ω
R2
C12
0.1µF
V_CC
R4
50kΩ
V_CC
C1
47pF
V_CC
RFIN
RFGND
RF OUT-
V_CC ^C14
47pF
VCC2
RF OUT+
C15
0.1µF
C15
0.1µF
R9
100Ω
R3
50kΩ
OP OUT
OPIN+
0.1µF
R10
3kΩ
D1
R8
V_CC
3kΩ R7
10kΩ
OP IN
BIAS
L_BIAS
R_BIAS
5.81Ω
D2
D1, D2 SMALL-SIGNAL SCHOTTKY DIODES, TYPICALLY CMDSH-3
Figure 1. MAX3524 EV Kit Schematic
RF OUTPUT
C2
2pF
75Ω
Z_S
2V_IN
RFIN
330Ω
V1
1.8pF
V_CC (PIN9)
A_V = (V_{RFOUT +}) - (V_RFOUT-) = 5.7
V_IN
A_V(dB) = 20log₁₀ A_V = 15dB
30Ω
30Ω
RFOUT+
0.06V1
RFOUT-
Figure 2. LNA Equivalent Circuit and Open-Circuit Voltage Gain Calculation
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