1FEATURES
2• Adjustable Gain with a 31 dB Range
• Precise 1 dB Gain Steps
• Parallel 5-bit Gain Control
• On Chip Register Stores Gain Setting
• Fully Differential Signal Path
• Single Ended to Differential Capable
• 200Ω Input Impedance
• Small Footprint (4 mm x 4 mm) WQFN Package

APPLICATIONS
• Cellular Base Stations
• IF Sampling Receivers
• Instrumentation
• Modems
• Imaging
• Differential Line Receiver

KEY SPECIFICATIONS
• 600 MHz bandwidth @ 100Ω load
• 40 dBm OIP3 @ 75 MHz, 200Ω load
• 20 dB to 30 dB maximum gain
• Selectable output impedance of 200Ω or 400Ω
• 8.3 dB noise figure
• 5 ns gain step switching time
• 100 mA supply current

DESCRIPTION
The LMH6515 is a high performance, digitally
controlled variable gain amplifier (DVGA). It combines
precision gain control with a low noise, ultra-linear,
differential amplifier. Typically, the LMH6515 drives a
high performance ADC in a broad range of mixed
signal and digital communication applications such as mobile radio and cellular base stations where
automatic gain control (AGC) is required to increase
system dynamic range. When used in conjunction
with a high speed ADC, system dynamic range can
be extended by up to 32 dB.
The LMH6515 has a differential input and output
allowing large signal swings on a single 5V supply. It is designed to accept signals from RF elements and
maintain a terminated impedance environment. The
input impedance is 200Ω resistive. The output
impedance is either 200Ω or 400Ω and is user
selectable. A unique internal architecture allows use
with both single ended and differential input signals.
Input signals to the LMH6515 are scaled by a highly
linear, digitally controlled attenuator with 31 accurate
1 dB steps. The attenuator output provides the input
signal for a high gain, ultra linear differential
transconductor. The transconductor differential output current can be converted into a voltage by using the
on-chip 200Ω or 400Ω loads. The transconductance
gain is 0.1 Amp/Volt resulting in a maximum voltage
gain of +26 dB when driving a 200Ω load, or 32 dB
when driving the 400Ω load. On chip digital latches
are provided for local storage of the gain setting. The
gain step settling time is 5 ns and care has been
taken to reduce the sensitivity of bandwidth and
phase to gain setting.
The LMH6515 operates over the industrial
temperature range of −40°C to +85°C. The LMH6515
is available in a 16-Pin, thermally enhanced, WQFN
package.