Analog Devices AD8375 Service Manual

24dB Range, 1dB Step Size Programmable

Preliminary Technical Data

FEATURES

-4 to 20dB Gain Range

1 dB Step Size ± 0.2 dB
Differential input and output

150 Ω Differential Input

Open Collector Differential Output
8dB noise figure @ maximum gain
OIP3 of ~50dBm at 140MHz

−3 dB bandwidth of 690 MHz
Parallel 5-bit Control Interface
Wide input dynamic range
Power-down feature
Single 5V Supply Operation
24 Lead LFCSP 4 x 4 mm Package

APPLICATIONS

Differential ADC drivers
High IF Sampling Receivers
High Output Power IF Amplification
Instrumentation

GENERAL DESCRIPTION

The AD8375 is a digitally controlled, variable gain wide
bandwidth amplifier that provides precise gain control, high IP3
and low noise figure. The excellent distortion performance and
high signal bandwidth makes the AD8375 an excellent gain
control device for a variety of receiver applications.

For wide input dynamic range applications, the AD8375 pro­vides a broad 24dB gain range with 1 dB resolution. The gain is
adjusted through a 5-pin control interface and can be driven
using standard TTL levels. The open-collector outputs provide a
flexible interface, allowing the overall signal gain to be set by
the loading resistance. The AD8375 offers a maximum trans­conductance gain of 67 mΩ
when driving a 150-Ohm load. The maximum signal gain
increases to ~24dB when driving a 250-Ohm differential load.

-1

’s, resulting in a signal gain of 20dB

VGA

AD8375

FUNCTIONAL BLOCK DIAGRAM

Figure 1.

Using a high speed SiGe process and incorporating proprietary
distortion cancellation techniques, the AD8375 achieves
50 dBm output IP3 at 140 MHz.

The AD8375 is powered on by applying the appropriate logic
level to the PWUP pin. The quiescent current of the AD8375 is
typically 130mA. When powered down, the AD8375 consumes
less than 5mA and offers excellent input to output isolation. The
gain setting is preserved when powered down.

Fabricated on an ADI’s high speed SiGe process, the AD8375
provides precise gain adjustment capabilities with good distortion
performance. The AD8375 amplifier comes in a compact,
thermally enhanced 4 x 4mm 24-lead LFCSP package and
operates over the temperature range of −40°C to +85°C.

Rev. PrB March 13, 2007

Information furnished by Analog Devices is believed to be accurate and reliable.
However, no responsibility is assumed by Analog Devices for its use, nor for any
infringements of patents or other rights of third parties that may result from its use.
Specifications subject to change without notice. No license is granted by implication
or otherwise under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective owners.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone] www.analog.com
Fax: [phone] © 2007 Analog Devices, Inc. All rights reserved.

AD8375 Preliminary Technical Data

SPECIFICATIONS

VS = 5 V, T = 25°C, ZS = ZL = 150Ω at 100MHz, 2 V p-p differential output unless otherwise noted.

Tabl e 1.

Parameter Conditions Min Typ Max Unit

DYNAMIC PERFORMANCE

−3 dB Bandwidth V
Slew Rate

INPUT STAGE

Maximum Input Swing For linear operation (AV = 0dB)
Differential Input Resistance Differential
Common-Mode Input Voltage
CMRR Gain Code = 00000

GAIN

Amplifier Transconductance

Maximum Voltage Gain Gain Code = 00000

Minimum Voltage Gain

Gain Step Size From Gain Code 00000 to 11000

Gain Flatness

Gain Temperature Sensitivity Gain Code = 00000

Gain Step Response For VIN = 0.2V, Gain Code 10100 to 00000

OUTPUT STAGE

Output Voltage Swing At P1dB, Gain Code = 00000
Output impedance Differential

NOISE/HARMONIC PERFORMANCE

46 MHz Gain Code = 00000

Noise Figure
Second Harmonic V
Third Harmonic V
Output IP3 2 MHz spacing, +3 dBm per tone

Output 1 dB Compression Point

70 MHz Gain Code = 00000

Noise Figure
Second Harmonic V
Third Harmonic V
Output IP3 2 MHz spacing, +3 dBm per tone
Output 1 dB Compression Point

140 MHz Gain Code = 00000

Noise Figure
Second Harmonic V
Third Harmonic V
Output IP3 2 MHz spacing, +3 dBm per tone
Output 1 dB Compression Point

< 2 V p-p (5.2dBm)

OUT

690
TBD

MHz
V/nsec

Pins VIN+ and VIN-

TBD
150
2
TBD

V p-p
Ω
V
dB

-1

Ω

dB

dB

dB

dB

mdB/°C

Gain Code ≥11000

Gain Code = 00000 over 20% fractional
bandwidth for f

< 200MHz

C

0.58

-5.5

0.8

0.067 0.076

20

−4

1.0

TBD

TBD

TBD

-2.5

1.2

ns

Pins OUT+ and OUT-

10
5k//1

V p-p
Ω/pF

= 2 V p-p

OUT

= 2 V p-p

OUT

8.5

-94

-92
50

19

dB
dBc
dBc
dBm

dBm

= 2 V p-p

OUT

= 2 V p-p

OUT

8.5

-94

-92
50

19

dB
dBc
dBc
dBm
dBm

= 2 V p-p

OUT

= 2 V p-p

OUT

8.5

-86

-91
50
19

dB
dBc
dBc
dBm
dBm

Rev. PrB | Page 2 of 6