LMH6505 Datasheet, PDF (1/20 Pages) National Semiconductor (TI) – Wideband, Low Power, Linear-in-dB, Variable Gain Amplifier

January 2006
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 op
amp which can directly drive a low impedance load. The gain
adjustment range is 80 dB for up to 10 MHz which is accom-
plished 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 cut-off. 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 maxi-
mum gain. Furthermore, gain is tested and guaranteed 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) 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 @
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 SOIC-8 or the
MSOP-8 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.
n −3 dB BW
150 MHz
n Gain control BW
100 MHz
n Adjustment range (<10 MHz)
80 dB
n Gain matching (limit)
±0.50 dB
n Supply voltage range
7V to 12V
n Slew rate (inverting)
1500 V/µs
n Supply current (no load)
11 mA
n Linear output current
±60 mA
n Output voltage swing
±2.4V
n Input noise voltage
4.4 nV/
n Input noise current
2.6 pA/
n THD (20 MHz, R_L = 100Ω, V_O = 2 V_PP)
−45 dBc
Applications
n Variable attenuator
n AGC
n Voltage controlled filter
n Video imaging processing
Typical Application
Gain vs. V_G
20171011
© 2006 National Semiconductor Corporation DS201710
A_VMAX = 9.4 V/V
20171002
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