ADA4938-2 Ultralow Distortion Differential ADC Driver (Dual)

The ADA4938-1 / ADA4938-2 are low noise, ultralow distortion, high speed differential amplifiers. It is an ideal choice for driving high performance ADCs with resolutions up to 16 bits from dc to 27 MHz, or up to 12 bits from dc to 74 MHz. The output common-mode voltage is adjustable over a wide range, allowing the ADA4938-1/ADA4938-2 to match the input of the ADC. The internal common-mode feedback loop also provides exceptional output balance as well as suppression of even-order harmonic distortion products.

Full differential and single-ended-to-differential gain configurations are easily realized with the ADA4938-1/ADA4938-2. A simple external feedback network of four resistors determines the closed-loop gain of the amplifier.

The ADA4938-1 / ADA4938-2 are fabricated using the Analog Devices, Inc., proprietary third generation, high voltage XFCB process, enabling it to achieve very low levels of distortion with an input voltage noise of only 2.6 nV/√Hz. The low dc offset and excellent dynamic performance of the ADA4938-1/ADA4938-2 makes them well-suited for a wide variety of data acquisition and signal processing applications.

The ADA4938-1 (single amplifier) is available in a Pb-free, 3 mm × 3 mm, 16-lead LFCSP. The ADA4938-2 (dual amplifier) is available in a Pb-free, 4 mm × 4 mm, 24-lead LFCSP. The pinouts have been optimized to facilitate layout and minimize distortion. The devices are specified to operate over the extended industrial temperature range of −40°C to +85°C.

Applications

Features and Benefits

Extremely low harmonic distortion (HD)

−106 dBc HD2 at 10 MHz

−82 dBc HD2 at 50 MHz

−109 dBc HD3 at 10 MHz

−82 dBc HD3 at 50 MHz

Low input voltage noise: 2.6 nV/√Hz

High speed

−3 dB bandwidth of 1000 MHz, G = +1

Slew rate: 4700 V/μs

0.1 dB gain flatness to 150 MHz

Fast overdrive recovery of 4 ns

1 mV typical offset voltage

Externally adjustable gain

Differential-to-differential or single-ended-to-differential operation

Adjustable output common-mode voltage

Wide supply voltage range: +5 V to ±5 V

Single or dual amplifier configuration available

Amplifiers

SPICE Models

ADA4938 SPICE Macro Model .CIR

Data Sheets

Document	note
ADA4938-1/ADA4938-2: Ultralow Distortion Differential ADC Driver Data Sheet (Rev. B)	PDF 591.24 K

Application Notes

Document	note
AN-1363: Meeting Biasing Requirements of Externally Biased RF/Microwave Amplifiers with Active Bias Controllers (Rev. 0)	PDF 804.11 K
AN-282: Fundamentals of Sampled Data Systems	PDF 2131 kB
AN-0990: Terminating a Differential Amplifier in Single-Ended Input Applications (Rev. 0)	PDF 181 kB
AN-0992: Active Filter Evaluation Board for Differential Amplifiers (Rev. 0)	PDF 85 kB
AN-1026: High Speed Differential ADC Driver Design Considerations (Rev. A)	PDF 355 kB
AN-649: Using the Analog Devices Active Filter Design Tool (Rev. 0)	PDF 5.3 M
AN-584: Using the AD813X Differential Amplifier (Rev. 0)	PDF 174 kB
AN-589: Ways to Optimize the Performance of a Difference Amplifier (Rev. B)	PDF 115 kB

User Guides

Document	note
UG-018: Evaluation Board for Dual High Speed Differential Amplifiers	PDF 314 kB

Order Information

Part Number	Package	Packing Qty	Temp Range	Price 100-499	Price 1000+	RoHS
ADA4938-2ACPZ-R2 Production	24 ld LFCSP (4x4x.75mm w/2.10mm EP)	REEL 250	-40 to 85C	7.69	7.69	Y
ADA4938-2ACPZ-R7 Production	24 ld LFCSP (4x4x.75mm w/2.10mm EP)	REEL 1500	-40 to 85C	0	5.69	Y
ADA4938-2ACPZ-RL Production	24 ld LFCSP (4x4x.75mm w/2.10mm EP)	REEL 5000	-40 to 85C	0	5.69	Y