MAX2511EVKIT Maxim Integrated Products, MAX2511EVKIT Datasheet - Page 4

• Manufacturer Part Number: MAX2511EVKIT
• Description: RF Modules & Development Tools MAX2511 EVAL KIT MAX2511 EVAL KIT
• Manufacturer: Maxim Integrated Products

Specifications of MAX2511EVKIT

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

network has some attenuation, but presents the correct
impedance to the MIXOUT pin and provides a nearly
50Ω output impedance for measurement. The voltage
attenuation is 21.4dB.
The limiter input pin (LIMIN) requires a DC bias level
set by the VREF pin. To present this bias level, resistors
R10 + R11 and R1 + R13 and are connected to VREF
and not to ground. To minimize noise, this voltage is
bypassed with capacitor C21 to ground.
The oscillator tank shipped with the EV kit is configured
for operation at a 425MHz IF frequency, with a
10.7MHz second IF. This places the desired oscillator
frequency at 435.7MHz. The oscillation frequency can
be controlled over approximately a 100MHz range by
adjusting the FADJ voltage from 0V to 3V. Do not apply
voltages higher than 10V to the FADJ connector.
If this frequency range does not cover your target IF
frequency, it is fairly simple to retune the oscillator by
adjusting capacitor C5 and inductor L1 (see the
MAX2511 data sheet for more information on oscillator
tank design).
The MAX2511 EV kit can be operated from an external
LO source with a few modifications (Figure 1). The fol-
lowing components must be removed entirely: R2, R4,
Figure 1. LO Overdrive Circuit
4
MAX2511 Evaluation Kit
_______________________________________________________________________________________
PIN = -3dBm SMA
PIN = -3dBm SMA
FADJ
LO
LO
J2
J3
(REMOVE)
(REMOVE)
1k
R2
1k
47pF
R4
C28
47pF
C27
47nF
C26
Oscillator Tank
10k
R3
LO Overdrive
(REMOVE)
D1
ADD C27 AND C28 47pF CAPACITORS, J2 AND J3 SMA CONNECTORS.
REMOVE R2, R4, C5, AND D1. REPLACE C6 AND C7 WITH 0 SHORTS.
REPLACE L1 WITH A 100 RESISTOR.
(REPLACE WITH
(REPLACE WITH
0 SHORT)
0 SHORT)
C6
C7
C5, and D1. Add capacitors C27 and C28 (both 47pF
SMT capacitors). Add J2 and J3 (top-mount SMA con-
nectors). Replace C6 and C7 with 0Ω shorts and L1
with a 100Ω resistor. These modifications allow a differ-
ential LO source to be AC coupled into the TANK and
TANK pins. The circuit can then be driven from a differ-
ential LO source at LO and LO with a power level of
-3dBm per side (0dBm total). The external signal
source used can be split into LO and LO with an addi-
tional 180° balun of the same type as mentioned in the
Test Equipment Required section. For optimum LO
suppression and image rejection, a differential LO
source is recommended if overdriving LO.
A good PC board is an essential part of an RF circuit
design. The EV kit PC board can serve as a guide for
laying out a board using the MAX2511.
Remove the ground plane directly under LO tank com-
ponents, IF port coupling components, and limiter out-
puts (Figure 5).
The RXIN and RXIN input coupling network should be
symmetrical to provide the best input balance if used
as a differential input. The TXOUT and TXOUT biasing
networks should also be symmetrical to present an
equivalent load on each pin.
C5
(REMOVE)
L1
100
(REPLACE L1
WITH 100 )
Rx Inputs and Tx Outputs
6
9
TANK
TANK
MAX2511
Layout Issues