Rainbow Electronics MAX2130 - Manual (Page 7)

Dynamic Linearity Adjustment
The LNA and loop-out amplifier linearity can be dynam-
ically adjusted by varying the amount of current
sourced by the BIAS port. The BIAS port is internally
biased to 1.2V. A resistor, R
BIAS , connected from BIAS
to ground sets the bias current. An additional resistor,
R
ADJ , placed from the BIAS port to an external voltage
source, such as a digital-to-analog converter (DAC),
varies the current sourced by the BIAS port. Choosing
R
ADJ = R BIAS = 20k Ω and varying the voltage of the
DAC from ground to 2.4V effectively varies the resis-
tance seen from the BIAS port from 10k
Ω to an open
circuit. See Typical Application Circuit.
The DAC output voltage, V ADJ , required to set an equiv-
alent resistance to ground, R EQ , seen by the BIAS port,
can be calculated with the following equation:
V ADJ = 2.4V - (R BIAS
✕ V BIAS ) / R EQ
where R ADJ = R BIAS , V BIAS = 1.2V, R EQ
≥ 10kΩ.
Power-Supply Bypassing
Proper voltage-supply bypassing is essential for high-
frequency circuit stability. Bypass the V
CC pin with a
1000pF capacitor in parallel with a 47pF capacitor,
located as close to the V
CC pin as possible. Refer to
the MAX2130 EV kit for additional information.
MAX2130
Broadband, Two-Output, Low-Noise
Amplifier for TV Tuner Applications
_______________________________________________________________________________________ 7
GND
OUT2 GND
1
2
8
7
OUT1
GND IN
BIAS
V
CC
µMAX-EP
TOP VIEW
3
4
6
5
MAX2130
Pin Configuration Chip Information
TRANSISTOR COUNT: 167