Analog Devices Inc. AD8138AARZ-RL

Overview

AD8138AARZ-RL from Analog Devices is a high-speed, low-distortion differential ADC driver IC designed for single-ended-to-differential signal conversion in precision data acquisition systems. It delivers −94 dBc SFDR at 5 MHz, 320 MHz −3 dB bandwidth (G = +1), 1150 V/µs slew rate, and adjustable output common-mode voltage via VOCM pin - enabling direct interface with single-supply, high-resolution ADCs.

For engineers reviewing the AD8138AARZ-RL datasheet, AD8138AARZ-RL pinout, AD8138AARZ-RL application, or AD8138AARZ-RL equivalent, key selection criteria include differential output balance error (−66 dB), fast 4 ns overdrive recovery, 5 nV/√Hz input voltage noise, and SOIC-8 package compatibility with industrial temperature range (−40°C to +85°C).

Technical Context

The AD8138AARZ-RL employs a dual-feedback architecture: one loop controls differential output voltage using external resistors (RG/RF), while an internal common-mode feedback loop forces output common-mode voltage to precisely track the VOCM input voltage (1:1 ratio). This eliminates gain error from resistor mismatch and suppresses even-order harmonics via balanced phase/amplitude matching.

It operates on ±1.4 V to ±5.5 V or +2.7 V to +11 V supplies, supports both single-ended and differential inputs, and maintains 0.1 dB gain flatness to 40 MHz. Its XFCB bipolar process enables low input bias current (3.5–7 µA), high CMRR (−77 dB), and robust drive capability into 500 Ω differential loads.

Key Specifications

Pinout & Package

AD8138AARZ-RL is housed in an 8-lead SOIC package (body width 3.9 mm, JEDEC MS-012), RoHS-compliant, rated for −40°C to +85°C operation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar differential ADC driver applications.

Compared with THS4561IRGET and LMH5401RTVT, the AD8138AARZ-RL uniquely combines VOCM adjustability, −94 dBc SFDR at 5 MHz, and SOIC-8 manufacturability - making it optimal for cost-sensitive, high-SNR industrial and communications data acquisition where DC accuracy and flexible level-shifting are mandatory.

Availability

AD8138AARZ-RL is available at Aetrix Electronics and suitable for high-speed data acquisition, communications IF amplification, digital imaging signal chains, and test & measurement instrumentation requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for AD8138AARZ-RL includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Analog Devices, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, headquartered in Norwood, MA.

The AD8138 belongs to Analog Devices' precision high-speed amplifier product line, engineered specifically for demanding differential signal conditioning in data converters, communications infrastructure, and instrumentation - emphasizing distortion performance, common-mode control, and ease of use.

FAQ

What is the maximum differential output voltage swing of the AD8138AARZ-RL at ±5 V supply?

The AD8138AARZ-RL delivers a maximum differential output voltage swing of 7.75 V p-p under ±5 V supply conditions, corresponding to ±3.875 V per output relative to ground. This is specified with RL,dm = 500 Ω and accounts for headroom limitations of the internal output stage. The actual usable swing depends on load impedance and VOCM setting, but the 7.75 V p-p value represents the guaranteed minimum under standard test conditions defined in the Rev. G datasheet.

Can the AD8138AARZ-RL operate from a single +5 V supply?

Yes, the AD8138AARZ-RL supports single-supply operation from +2.7 V to +11 V. At +5 V, it achieves 2.9 V p-p single-ended output swing and maintains −90 dBc SFDR at 5 MHz. The VOCM pin must be biased within the valid input common-mode range (1.0 V to 3.8 V), typically at 2.5 V, to center the differential outputs for optimal ADC interface. Quiescent current drops to 20 mA typical, reducing power dissipation versus dual-supply mode.

How does the VOCM pin function in the AD8138AARZ-RL?

The VOCM pin on the AD8138AARZ-RL directly sets the common-mode voltage of both +OUT and −OUT terminals with a 1:1 ratio - a 2.5 V input produces 2.5 V dc on each output. This internal common-mode feedback loop operates independently of the differential gain path, enabling precise level-shifting without affecting gain accuracy or introducing resistor-matching errors. It is essential for interfacing with single-supply ADCs whose input common-mode range is fixed (e.g., AVDD/2).

What is the recommended minimum load impedance for the AD8138AARZ-RL to maintain specified distortion performance?

To maintain the −94 dBc SFDR at 5 MHz and other distortion specifications, the AD8138AARZ-RL should drive a minimum differential load of 500 Ω (250 Ω per output to ground). Lower impedances increase harmonic distortion - Figure 17 shows SFDR degrading by ~6 dB when RLOAD decreases from 800 Ω to 200 Ω. For 50 Ω systems, external termination or a buffer stage is required to avoid violating the specified AC performance.

Does the AD8138AARZ-RL require external compensation capacitors for stability?

The AD8138AARZ-RL is unity-gain stable and does not require external compensation capacitors for basic configurations. However, the datasheet recommends adding small feedback capacitors (CF = 0–1 pF) to optimize bandwidth flatness and reduce peaking - especially when driving capacitive loads >1 pF or operating at gains >+2. Figure 6 and Figure 9 confirm stable response with CF = 0 pF at G = +1, but CF = 1 pF improves 0.1 dB flatness bandwidth by ~10 MHz.