Datasheet

V
IN
1
8
3
2
5
4
7
6
R
F
1 k:
R
L
100:
R
G
100:
V
-
V
+
V
G
-0.5
0 0.5 1 1.5
V
G
(V)
GAIN (dB)
2
-90
-70
-50
30
-30
-10
10
0
2
4
12
6
8
10
GAIN
(
V
/
V
)
11
9
7
5
3
1
dB
V/V
125°C
25°C
-55°C
125°C
25°C
-55°C
LMH6505
www.ti.com SNOSAT4E –DECEMBER 2005–REVISED APRIL 2013
LMH6505 Wideband, Low Power, Linear-in-dB, Variable Gain Amplifier
Check for Samples: LMH6505
Near ideal input characteristics (i.e. low input bias
1
FEATURES
current, low offset, low pin 3 resistance) enable the
2
• V
S
= ±5V, T
A
= 25°C, R
F
= 1 kΩ, R
G
= 100Ω, R
L
=
device to be easily configured as an inverting
100Ω, A
V
= A
VMAX
= 9.4 V/V, Typical Values
amplifier as well.
Unless Specified.
To provide ease of use when working with a single
• −3 dB BW 150 MHz
supply, the V
G
range is set to be from 0V to +2V
• Gain Control BW 100 MHz
relative to the ground pin potential (pin 4). V
G
input
impedance is high in order to ease drive requirement.
• Adjustment Range (<10 MHz) 80 dB
In single supply operation, the ground pin is tied to a
• Gain Matching (Limit) ±0.50 dB
"virtual" half supply.
• Supply Voltage Range 7V to 12V
The LMH6505’s gain control is linear in dB for a large
• Slew Rate (Inverting) 1500 V/μs
portion of the total gain control range from 0 dB down
• Supply Current (No Load) 11 mA
to −85 dB at 25°C, as shown below. This makes the
device suitable for AGC applications. For linear gain
• Linear Output Current ±60 mA
control applications, see the LMH6503 datasheet.
• Output Voltage Swing ±2.4V
The LMH6505 is available in either the 8-Pin SOIC or
• Input Noise Voltage 4.4 nV/√Hz
the 8-Pin VSSOP package. The combination of
• Input Noise Current 2.6 pA/√Hz
minimal external components and small outline
• THD (20 MHz, R
L
= 100Ω, V
O
= 2 V
PP
) −45 dBc
packages allows the LMH6505 to be used in space-
constrained applications.
APPLICATIONS
• Variable Attenuator
• AGC
• Voltage Controlled Filter
• Video Imaging Processing
DESCRIPTION
The LMH6505 is a wideband DC coupled voltage
controlled gain stage followed by a high speed
current feedback operational amplifier which can
directly drive a low impedance load. The gain
adjustment range is 80 dB for up to 10 MHz which is
accomplished by varying the gain control input
Figure 1. Gain vs. V
G
voltage, V
G
.
Maximum gain is set by external components, and
the gain can be reduced all the way to cutoff. Power
Typical Application
consumption is 110 mW with a speed of 150 MHz
and a gain control bandwidth (BW) of 100 MHz.
Output referred DC offset voltage is less than 55 mV
over the entire gain control voltage range. Device-to-
device gain matching is within ±0.5 dB at maximum
gain. Furthermore, gain is tested and ensured over a
wide range. The output current feedback op amp
allows high frequency large signals (Slew Rate =
1500 V/μs) and can also drive a heavy load current
(60 mA) ensured.
Figure 2. A
VMAX
= 9.4 V/V
1
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PRODUCTION DATA information is current as of publication date.
Copyright © 2005–2013, Texas Instruments Incorporated
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.