Rainbow Electronics MAX2685 - Manual (Page 9)

MAX2685
Low-Cost, 900MHz, Low-Noise Amplifier
and Downconverter Mixer
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Local-Oscillator Input
The LO port is the high-impedance input of the local-
oscillator buffer. It requires a series DC-blocking
capacitor and a shunt resistor to ground to set the input
impedance. See the Typical Operating Characteristics
for a graph of LO Port Return Loss vs. Frequency.
IF Output Port
The mixer’s downconverted output appears on the dif-
ferential IFOUT+ and IFOUT- pins. The differential out-
put can be converted to a single-ended output, as
shown in the MAX2685 evaluation kit (EV kit). Refer to
the Detailed Description in the MAX2685 EV kit data
sheet.
Shutdown
Drive SHDN low to disable all device functions and
place the MAX2685 in low-power shutdown mode.
Drive SHDN high or connect it to V
CC to enable all
device functions.
Applications Information
Layout Considerations
A properly designed PC board is an essential part of
any RF/microwave circuit. Note the IC’s high-frequency
inputs and outputs, and be sure to decouple the DC
supply and control pins.
For power-supply traces and connections, a star topol-
ogy works well. Each V
CC node in the circuit has its
own path to the central V CC node and a decoupling
capacitor that provides a low impedance at the RF fre-
quency of interest. The central V
CC also has a large
decoupling capacitor. This provides good isolation
between the different sections of the MAX2685.
Chip Information
TRANSISTOR COUNT: 295