Low Distortion, 3.2 GHz, RF DGA

Data Sheet

ADA4961

Rev. C

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FEATURES

High speed

−3 dB bandwidth: 3.2 GHz

−1 dB bandwidth: 1.8 GHz

Slew rate: 12,000 V/μs

Digitally adjustable gain

Voltage gain: −6 dB to +15 dB

Power gain: −3 dB to +18 dB

5-bit parallel or SPI bus gain control with fast attack

IMD3/HD3 distortion, maximum gain, 5 V, high performance

(HP) mode

IMD3/HD3 at 1 GHz: −90 dBc/−83 dBc

IMD3/HD3 at 1.5 GHz: −85 dBc/−75 dBc

IMD3/HD3 at 2 GHz: −70 dBc/−70 dBc

Low noise

Noise density referred to output (RTO): −154 dBm/Hz

Noise figure: 5.5 dB at AV = 15 dB, 1 GHz

Differential impedances: 100 Ω input, 50 Ω output

Low power mode operation, power-down control

Single 3.3 V or 5 V supply operation

Available in 24-lead, 4 mm × 4 mm LFCSP

APPLICATIONS

ADC driver for 10-bit to 14-bit GSPS converters

RF/IF gain blocks

Line drivers

Instrumentation

Satellite communications

Data acquisition

Military systems

FUNCTIONAL BLOCK DIAGRAM

0dB TO 21dB

ATTEN

EXPOSED

PAD

2

3

18

14

15

17

16

4

5

1

7

8

9

10

11

24

23

22

21

20

19

12

13

6

VIN+

VIN–

VOUT+

VOUT–

DNC

DNC

DNC

GND

GND

+15dB

ADA4961

NOTES

1. DNC = DO NOT CONNECT. DO NOT CONNECT TO THIS PIN.

Figure 1.

GENERAL DESCRIPTION

The ADA4961 is a high performance, BiCMOS RF digital gain

amplifier (DGA), optimized for driving heavy loads out to

2.0 GHz and beyond. The device typically achieves −90 dBc

IMD3 performance at 500 MHz and −85 dBc at 1.5 GHz. This

RF performance allows GHz converters to achieve their optimum

performance with minimal limitations of the driver amplifier or

constraints on overall power that typically result from GaAs

amplifiers. This device can easily drive 10-bit to16-bit HS

converters.

For many receiver applications, antialias filter (AAF) designs

can be simplified or not required.

The ADA4961 has an internal differential input impedance of

100 Ω and a differential dynamic output impedance of 50 Ω,

eliminating the need for external termination resistors. The

digital adjustability provides for 1 dB resolution, thus optimizing

the signal-to-noise ratio (SNR) for input levels spanning 21 dB.

The ADA4961 is optimized for wideband, low distortion

performance at frequencies up to 2 GHz. These attributes,

together with wide gain adjustment and relatively low power,

make the ADA4961 the amplifier of choice for many high speed

applications, including IF, RF, and broadband applications

where dynamic range at very high frequencies is critical.

The ADA4961 is ideally suited for driving not only analog-to-

digital converters (ADCs), but also mixers, pin diode attenuators,

SAW filters, and multielement discrete devices. It is available in

a 4 mm × 4 mm, 24-lead LFCSP and operates over a

temperature range of −40°C to +85°C.