HFA1405 Datasheet, PDF (6/13 Pages) Intersil Corporation – Quad, 560MHz, Low Power, Video Operational Amplifier

HFA1405
Figure 1 details starting points for the selection of this
resistor. The points on the curve indicate the R_S and C_L
combinations for the optimum bandwidth, stability, and
settling time, but experimental fine tuning is recommended.
Picking a point above or to the right of the curve yields an
overdamped response, while points below or left of the curve
indicate areas of underdamped performance.
R_S and C_L form a low pass network at the output, thus limiting
system bandwidth well below the amplifier bandwidth of
560MHz. By decreasing R_S as C_L increases (as illustrated in
the curve), the maximum bandwidth is obtained without
sacrificing stability. In spite of this, bandwidth still decreases
as the load capacitance increases.
R_S
50Ω
OUT
1
R_G R_F
2
-
IN
3
+
50Ω
4
+5V
10µF
5
0.1µF ⁶
7
14
13
12
11
-5V
10
0.1µF
10µF
9
8
GND
GND
FIGURE 2. EVALUATION BOARD SCHEMATIC
50
TOP LAYOUT
40
30
20
A_V = +2
10
0
0 50 100 150 200 250 300 350 400
LOAD CAPACITANCE (pF)
FIGURE 1. RECOMMENDED SERIES OUTPUT RESISTOR vs
LOAD CAPACITANCE
Evaluation Board
The performance of the HFA1405 (PDIP) may be evaluated
using the HA5025 Evaluation Board.
The schematic for amplifier 1 and the board layout are
shown in Figure 2 and Figure 3. Resistors R_F, R_G, and R_S
may require a change to values applicable to the HFA1405.
To order evaluation boards (part number HA5025EVAL),
please contact your local sales office.
BOTTOM LAYOUT
FIGURE 3. EVALUATION BOARD LAYOUT
6