Rainbow Electronics MAX2684 - Manual (Page 15)

MAX2683/MAX2684
3.5GHz Downconverter Mixers
with Selectable LO Doubler
______________________________________________________________________________________ 15
as well as an output matching network for optimum per-
formance. See Typical Operating Circuit for recommend-
ed component values. See Tables 4 and 5 for IFOUT
port S-parameters.
Bias Circuitry
The linearity and supply current of the MAX2683/
MAX2684 are externally programmable with a single
resistor, R
BIAS , from BIAS to GND. A nominal resistor
value of 1.2k
Ω will set an IIP3 of +9dBm and a supply
current of 55mA. Decreasing the resistor value
improves linearity at the cost of increased supply cur-
rent. Increasing the resistor value decreases supply
current while degrading linearity. Use resistor values in
the range of 820k
Ω to 2kΩ.
___________Applications Information
Layout Considerations
A properly designed PC board is an essential part of
any RF/microwave circuit. Keep RF signal lines as short
as possible to reduce losses, radiation, and induc-
tance. Use separate, low-inductance vias to the ground
plane for each ground pin. For best performance, sol-
der the exposed pad on the bottom of the device pack-
age evenly to the board ground plane.
Power-Supply and
ENX2
Bypassing
Proper voltage-supply bypassing is essential for high-
frequency circuit stability. Bypass V
CC with a 10µF
capacitor in parallel with a 100pF capacitor located as
close to the V
CC
pin as possible.
Bypass ENX2 with a 100pF capacitor to ground to mini-
mize noise injected into the LO doubler cell. Use a
series resistor (typically 1.2k
Ω) to further reduce cou-
pling of high-frequency signals into the ENX2 pin.
R BIAS = 1.2k Ω
S11 PHASE
(degrees)
-10.9
-23.5
-20.3
-17.2
-14.2
R BIAS = 1.2k Ω
S11 MAG
S11 PHASE
(degrees)
S11 MAG
0.914 -11.2 0.930
0.893 -24.5 0.907
0.900 -21.3 0.911
0.905 -17.8 0.917
0.905 -14.7 0.920
R BIAS = 820 Ω
RF
FREQUENCY
(MHz)
S11 MAG
S11 PHASE
(degrees)
150 0.915 -11.3
350 0.894 -24.5
300 0.899 -21.3
250 0.904 -17.7
200 0.907 -14.8
R
BIAS
= 1.2k Ω
S11 PHASE
(degrees)
-49.7
-53.3
-52.3
-51.4
-50.6
960
R
BIAS
= 1.2k Ω
S11 MAG
S11 PHASE
(degrees)
S11 MAG
0.955 -49.6 0.955
0.940 -53.1 0.937
0.944 -52.3 0.941
0.948 -51.4 0.946
0.952 -50.5 0.950
R
BIAS
= 820 Ω
RF
FREQUENCY
(MHz) S11 MAG
S11 PHASE
(degrees)
860 0.955 -49.4
940 0.943 -53.0
920 0.946 -52.0
900 0.950 -51.1
880 0.952 -50.3
0.941 -53.6 0.936 -54.0 0.935 -53.8
Table 5. MAX2684 IFOUT Port S-Parameters (V CC = +5V, T A = +25°C)
Table 4. MAX2683 IFOUT Port S-Parameters (V CC = +5V, T A = +25°C)