LMH6505 Datasheet, PDF (1/18 Pages) National Semiconductor (TI) – Wideband, Low Power, Linear-in-dB, Variable Gain Amplifier

December 14, 2007
LMH6505
Wideband, Low Power, Linear-in-dB, Variable Gain
Amplifier
General Description
The LMH6505 is a wideband DC coupled voltage controlled
gain stage followed by a high speed current feedback opera-
tional 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 voltage,
V_G.
Maximum gain is set by external components, and the gain
can be reduced all the way to cutoff. Power consumption is
110 mW with a speed of 150 MHz and a gain control band-
width (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 guaranteed over a wide
range. The output current feedback op amp allows high fre-
quency large signals (Slew Rate = 1500 V/μs) and can also
drive a heavy load current (60 mA) guaranteed. Near ideal
input characteristics (i.e. low input bias current, low offset, low
pin 3 resistance) enable the device to be easily configured as
an inverting amplifier as well.
To provide ease of use when working with a single supply, the
V_G range is set to be from 0V to +2V relative to the ground pin
potential (pin 4). V_G input impedance is high in order to ease
drive requirement. In single supply operation, the ground pin
is tied to a "virtual" half supply.
The LMH6505’s gain control is linear in dB for a large portion
of the total gain control range from 0 dB down to −85 dB at
25°C, as shown below. This makes the device suitable for
AGC applications. For linear gain control applications, see the
LMH6503 datasheet.
The LMH6505 is available in either the 8-Pin SOIC or the 8-
Pin MSOP package. The combination of minimal external
components and small outline packages allows the LMH6505
to be used in space-constrained applications.
Features
V_S = ±5V, T_A = 25°C, R_F = 1 kΩ, R_G = 100Ω, R_L = 100Ω,
A_V = A_VMAX = 9.4 V/V, Typical values unless specified.
■ ^{−3 dB BW}
150 MHz
■ ^{Gain control BW}
100 MHz
■ ^{Adjustment range (<10 MHz)}
80 dB
■ ^{Gain matching (limit)}
±0.50 dB
■ ^{Supply voltage range}
7V to 12V
■ ^{Slew rate (inverting)}
1500 V/μs
■ ^{Supply current (no load)}
11 mA
■ ^{Linear output current}
±60 mA
■ ^{Output voltage swing}
±2.4V
■ ^{Input noise voltage}
4.4 nV/√Hz
■ ^{Input noise current}
2.6 pA/√Hz
■ ^{THD (20 MHz, R}_L ^{= 100Ω, V}_O ^{= 2 V}_PP⁾
−45 dBc
Applications
■ ^{Variable attenuator}
■ ^AGC
■ ^{Voltage controlled filter}
■ ^{Video imaging processing}
Typical Application
Gain vs. V_G
20171011
© 2007 National Semiconductor Corporation 201710
A_VMAX = 9.4 V/V
20171002
www.national.com