MAX2170 datasheet(4/8 Pages) MAXIM

4 / 8 page

Note the 6dB loss at the output ports of the EV kit

due to the 50Ω resistor in series at the buffer out-

puts and the 50Ω load of the test equipment.

Gain Control

The RF and baseband VGA circuits of the MAX2170

are controlled independently through jumpers JP10

and JP4, respectively. Connecting pins 2-3 of JP10

closes the RF gain control loop. The MAX2170 EV kit

also implements a control loop for the baseband VGA

through shorting pins 1-2 of JP4. The HOLD_AGC con-

trols the MAX4729 analog switch (see Figure 1 for

schematic details). In typical applications, the demodu-

lator controls the baseband VGA. The analog switch

and the external AGC circuitry (Q1, Q2, and Q3) are

optional components and only needed when the

demodulator lacks a baseband AGC control circuit.

Layout Issues

A good PCB is an essential part of an RF circuit design.

The EV kit PCB serves as a guide for laying out a board

using the MAX2170. Keep traces carrying RF signals

as short as possible to minimize radiation and insertion

loss. Use impedance control on all RF signal traces.

The exposed paddle must be soldered evenly to the

board’s ground plane for proper operation. Use abun-

dant vias beneath the exposed paddle and between RF

traces to minimize undesired RF coupling.

To minimize coupling between different sections of the

IC, each VCC pin must have a bypass capacitor with low

impedance to the closest ground at the frequency of

interest. Do not share ground vias among multiple con-

nections to the PCB ground plane. Refer to the

Layout

section of the MAX2170 data sheet for more information.

MAX2170 Evaluation Kit

MAX2170 Datasheet(PDF) 4 Page - Maxim Integrated Products