MAX4146EEE Maxim Integrated, MAX4146EEE Datasheet - Page 12

• Manufacturer Part Number: MAX4146EEE
• Description: Special Purpose Amplifiers
• Manufacturer: Maxim Integrated
• Series: MAX4144, MAX4145, MAX4146r

Specifications of MAX4146EEE

• Number Of Channels: Single
• Common Mode Rejection Ratio (min): 80 dB
• Input Offset Voltage: 0.6 mV
• Maximum Power Dissipation: 667 mW
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C

Figure 2 shows the connection for R
be a resistor, or it can be a complex pole-zero pair for
filter and shaping applications (Figure 9). Use surface-
mount gain-setting components to ensure stability.
The MAX4144/MAX4145/MAX4146 have a REF pin (nor-
mally connected to ground) and a SENSE pin (normally
connected to OUT). In some long-line applications, it
may be desirable to connect SENSE and OUT together
at the load, instead of the typical connection at the part
(Figure 3). This compensates for the long line’s resis-
tance, which otherwise leads to an IR voltage error.
When using this technique, keep the sense lines’
impedance low to minimize gain errors. Also, keep
capacitance low to maximize frequency response. The
gain of the MAX4144/MAX4145/MAX4146 output stage
is approximated by the following equation:
where ΔR
trace impedances, respectively. R is 700Ω for the
MAX4144 and MAX4145, and 100Ω for the MAX4146.
High-Speed, Low-Distortion,
Differential Line Receivers
Figure 2. Connection of R
12
A =
V
______________________________________________________________________________________
+
1
2
R
⎡
⎢
⎣
SENSE
700
G = A = 1 +
G = A = 10 +
700
+
IN+
IN-
Ω
700
Ω
R
+
G
and ΔR
V
V
Ω
R
+
Δ
R
Δ
+
SENSE
R
G
Δ
REF
MAX4145
MAX4146
R
in MAX4146
REF
REF
1.4k
Using REF and SENSE
⎛
⎜
⎝
14k
R
1
R
⎤
⎥
⎦
G
are the SENSE and REF
G
+
Ω
Ω
R
(MAX4145)
(MAX4146)
700
+
G
. R
700
Ω
G
Ω
+
might simply
Δ
+
R
Δ
REF
R
REF
⎞
⎟
⎠
Additionally, mismatches in the SENSE and REF traces
lead to common-mode gain errors. Common-mode
gain is approximated by the following equation:
Substituting numbers for ΔR
equation, we can see that if changes in ΔR
ΔR
The MAX4144/MAX4145/MAX4146 provide maximum
AC performance when not driving an output load
capacitance. This is the case when driving a correctly
terminated transmission line (i.e., a back-terminated
cable). In most amplifier circuits, driving large load
capacitance increases the chance of oscillations. The
amplifier’s output impedance and the load capacitor
combine to add a pole and excess phase to the loop
response. If the pole’s frequency is low enough and
phase margin is degraded sufficiently, oscillations may
occur. A second concern when driving capacitive
loads results from the amplifier’s output impedance,
Figure 4. MAX4144 Small-Signal Response with Capacitive
Load
Figure 3. Connection of SENSE and REF to a Remote Load
SENSE
MAX4144
MAX4145
MAX4146
are equal, CMR is not degraded.
-1
-2
-3
-4
-5
5
4
3
2
1
0
100k
A
VCM
=
1M
Driving Capacitive Loads
Δ
R
FREQUENCY (Hz)
C
SENSE
OUT
REF
C
L
REF
L
= 10pF
R + 700
= 5pF
REF
10M
-
Δ
and ΔR
R
SENSE
100M
Ω
C
L
= 15pF
SENSE
1G
REF
into this
R
L
and