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.