LTC6420-20_15 Datasheet, PDF (7/14 Pages) Linear Technology – Dual Matched 1.8GHz Differential Amplifi ers/ADC Drivers

LTC6420-20
PIN FUNCTIONS
+INA, –INA, –INB, +INB (Pins 1, 2, 5, 6): Differential
Inputs of A and B channel respectively.
V^– (Pins 3, 4, 13, 14, 21): Negative Power Supply. All
four pins, as well as the exposed back, must be connected
to same voltage/ground.
ENABLEA, ENABLEB (Pins 9, 18): Logic inputs. If low,
the amplifier is enabled. If high, the amplifier is disabled
and placed in a low power shutdown mode, making
the amplifier outputs high impedance. These pins are
internally separate. These pins should not be left floating.
V⁺ A , V⁺ B (Pins 15, 20, 7, 12 ): Positive Power Supply
(Normally tied to 3V or 3.3V). Supply pins of A and B channels
are internally separate. Bypass each pin with 1000pF and
0.1μF capacitors as close to the pins as possible.
–OUTA, +OUTA, –OUTB, +OUTB (Pins 16, 17, 11, 10):
Differential Outputs of channels A and B respectively.
V_OCMA, V_OCMB (Pins 19, 8): These pins set the output
common mode voltage for the respective channel. They
are internally separate. A 0.1μF external bypass capacitor
is recommended.
Exposed Pad (Pin 21): V^–. The Exposed Pad must be
connected to same voltage/ground as pins 3, 4, 13, 14.
BLOCK DIAGRAM
+INA 1
–INA 2
V– ³
V– ⁴
–INB 5
+INB 6
V⁺ A
20
R_G
100Ω
R_G
100Ω
R_G
100Ω
R_G
100Ω
7
V⁺ B
V_OCMA
19
ENABLEA
18
+ OUTA
17
R_F
1000Ω
–– ++
++ ––
R_F
1000Ω
R_F
1000Ω
+–
–+
R_F
1000Ω
R_OUT
12.5Ω
R_OUT
12.5Ω
R_OUT
12.5Ω
R_OUT
12.5Ω
16 –OUTA
15 V ⁺ A
14 _V–
13 V–
12 V ⁺ B
11 –OUTB
8
V_OCMB
9
ENABLEB
10
640020 BD
+ OUTB
642020fb
7