MAX2634
315MHz/433MHz Low-Noise
Amplifier for Automotive RKE
6
Maxim Integrated
RF Input Coupling Capacitor
Input IP3 vs. Enable Time
The value of the coupling capacitor affects input IP3
and turn-on time. A larger coupling capacitor results in
higher input IP3 at the expense of longer turn-on time.
See Table 3 for the typical amount of trade-off.
Integrated Output Matching
Network and DC-Block
The MAX2634 integrates the output matching network
and DC-block, eliminating the need for external match-
ing components while providing a broadband match.
See the
Functional Diagram/Typical Operating Circuit
for component values.
Shutdown
The MAX2634 features a shutdown pin to disable the
entire chip. Apply a logic-high to the SHDN pin to place
the part in the active mode, and a logic-low to place the
part in the shutdown mode.
Power-Supply Bypassing
Bypassing the V
CC
line is necessary for optimum
gain/linearity performance. See the
Functional
Diagram/Typical Operating Circuit
for bypassing
capacitor values.
Layout Information
A properly designed PCB is essential to any RF/
microwave circuit. Use controlled-impedance lines on
all high-frequency inputs and outputs. Bypass with
decoupling capacitors located close to the device’s
V
CC
pin. For long V
CC
lines, it may be necessary to add
additional decoupling capacitors. These additional
capacitors can be located farther away from the device
package. Proper grounding of the GND pins is essen-
tial. If the PCB uses a topside RF ground, connect it
directly to all GND pins. For a board where the ground
plane is not on the component layer, the best technique
is to connect the GND pins to the board with a plated
through-hole located close to the package.
