MAX4063 MAXIM [Maxim Integrated Products], MAX4063 Datasheet - Page 8

• Manufacturer Part Number: MAX4063
• Description: Differential Microphone Preamplifier with Internal Bias and Complete Shutdown
• Manufacturer: MAXIM [Maxim Integrated Products]

book PCs or PDAs. Used correctly, the advantages
over a single-ended solution are:
• Better power-supply noise rejection.
• Less degradation from noise in PC board ground
• The microphone and preamplifier may be placed
The MAX4063 allows the user to alter the differential
gain to optimize the signal-to-noise ratio (SNR) of their
system. The gain is set by a single external resistor
(R
where A
Differential Microphone Preamplifier with
Internal Bias and Complete Shutdown
8
G
planes.
physically further apart, easing PC board layout
restrictions.
) connected between the G1 and G2 pins:
_______________________________________________________________________________________
V
is the required voltage gain.
R
G
=
Differential-Gain Adjustment
A
200k
VD
−
Ω
2
BIAS
BIAS
R
G
V
CC
12
14
10
1
9
3
AUX_IN
G1
G2
IN+
IN-
SHDN
Hence, an 11.11kΩ resistor yields a gain of 20V/V, or
26dB. Leaving the pins unconnected results in a gain of
2V/V. Gain is defined as:
For differential out:
The resistor can be either fixed or variable, allowing the
use of a digitally controlled potentiometer to alter the
gain under software control.
The MAX4063 provides an option to increase the
AUX_IN (see Figure 3). To increase the gain, connect
resistor R
calculated from the following formula:
SHDN
2.4V TO 5.5V
V
CC
6
GND
R
11
MAX4063
ADJ
ADJ
V
=
between the ADJ and AUX_IN pins. R
BIAS
INT/AUX
AV
OUT
OUT
ADJ
A
AUX
2M
VD
2
7
4
8
5
Ω
Auxiliary Input-Gain Adjustment
−
BIAS
=
20
Functional Diagram
V
OUT
V
(
IN+
to increase the gain
−
−
V
V
OUT
IN-
)
ADJ
is