MAX4060ETA-T Maxim Integrated, MAX4060ETA-T Datasheet - Page 9

• Manufacturer Part Number: MAX4060ETA-T
• Description: Microphone Preamplifiers
• Manufacturer: Maxim Integrated

The MAX4060 has an internal fixed gain of 10V/V for its
differential input. This feature simplifies design, reduces
pin count, footprint, and eliminates external gain-setting
resistors.
The MAX4061/MAX4062 allow the user to alter the gain
to optimize the signal-to-noise ratio (SNR) of their sys-
tem. The gain is set by a single external resistor (R
connected between the G1 and G2 pins, where:
where A
Hence, an 11.11kΩ resistor yields a gain of 10V/V, or
20dB. Leaving the pins unconnected results in a gain
of 1V/V. Gain for the MAX4061/MAX4062 is defined as:
The resistor can be either fixed or variable, allowing the
use of a digitally controlled potentiometer to alter the
gain under software control.
V
is the required voltage gain.
Differential Microphone Preamplifiers with
A
R
V
Adjustable Differential-Gain Setting
_______________________________________________________________________________________
G
= V
Fixed Differential Gain (MAX4060)
= 100kΩ / (A
OUT
Internal Bias and Complete Shutdown
/ (V
IN+
V
- V
- 1)
IN-
BIAS
)
BIAS
8 AUX_IN
5
6
IN+
IN-
G
)
x10
x10
The two differential microphone inputs and the single-
ended auxiliary input of the MAX4060/MAX4061/
MAX4062 have on-chip bias components, allowing the
user to AC-couple any signals onto the input. The input
resistance is 100kΩ (typ), so the capacitor size may be
chosen accordingly to define the LF rolloff desired. This
can be calculated as:
A further consideration for the differential input is the
effect of these series input capacitors on low-frequency,
common-mode rejection. Any mismatch in the values of
these two capacitors degrades the CMRR at frequen-
cies where the impedance of the capacitor is significant
compared to the input resistance of the amplifier—this is
usually most noticeable at low frequencies. One way to
avoid the need for matched or tight tolerance capaci-
tors is to deliberately oversize the values on the differ-
V
2.4V TO 5.5V
This assumes a low source impedance driving the inputs.
BIAS
GND
4
V
CC
7
MAX4060
INT/AUX 1
BIAS
OUT 2
C
3
IN
BIAS
= 1 / (2πf
Functional Diagram
CUT
R
IN
)
Input Capacitors
9