Analog Devices Inc. AD8138AARMZ

Overview

AD8138AARMZ 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), and 1150 V/µs slew rate under ±5 V supply, enabling direct drive of high-resolution (10–16-bit) analog-to-digital converters in communications and instrumentation.

For engineers reviewing the AD8138AARMZ datasheet, AD8138AARMZ pinout, AD8138AARMZ application, or AD8138AARMZ equivalent, this page provides verified specifications, validated MSOP-8 package mapping, confirmed VOCM-controlled common-mode level shifting, real-world settling time (16 ns to 0.01%), and two documented alternative drivers with quantified harmonic and bandwidth trade-offs.

Technical Context

The AD8138AARMZ employs a dual-feedback architecture: one loop controls differential output voltage via external resistors (RG/RF), while a separate internal common-mode feedback loop forces output common-mode voltage to precisely track the VOCM input pin voltage (1:1 ratio). This eliminates reliance on external resistor matching for balance.

Its proprietary XFCB bipolar process enables simultaneous high bandwidth (320 MHz), ultra-low distortion (−94 dBc HD2 at 5 MHz), and fast overdrive recovery (4 ns), making it suitable for wideband IF/baseband gain blocks where even-order harmonic suppression and dc-coupled level shifting are critical.

Key Specifications

Pinout & Package

AD8138AARMZ is housed in an 8-lead MSOP package (3 mm × 3 mm, 0.65 mm pitch), optimized for high-frequency layout with low parasitic inductance and thermal resistance (θJA = 145°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with THS4561IDGKT and LMH5401RTVT, the AD8138AARMZ uniquely combines VOCM-based common-mode control, −94 dBc SFDR at 5 MHz, and 320 MHz bandwidth in a low-power (90 mW), MSOP-8 package-making it the only option among the three qualified for precision, dc-coupled, transformerless ADC driving across industrial and communications platforms.

Availability

AD8138AARMZ is available at Aetrix Electronics and suitable for high-speed data acquisition, communications IF amplification, medical imaging signal chains, and industrial sensor interfaces requiring stable component supply across extended temperature ranges (−40°C to +85°C).

Supply support for AD8138AARMZ 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 transformerless differential signal conditioning in data converter interfaces, communications infrastructure, and test & measurement equipment.

FAQ

What is the maximum recommended supply voltage for AD8138AARMZ?

The AD8138AARMZ has an absolute maximum supply rating of ±5.5 V. For reliable long-term operation, Analog Devices specifies a recommended operating range of ±5 V (dual supply) or +3 V to +5 V (single supply). Exceeding ±5.5 V risks permanent damage per the Absolute Maximum Ratings table in Rev. G datasheet. The AD8138AARMZ achieves optimal distortion performance at ±5 V, with −94 dBc SFDR at 5 MHz confirmed under those conditions.

Can AD8138AARMZ operate from a single +5 V supply?

Yes, the AD8138AARMZ supports single +5 V operation with V− tied to ground. In this configuration, the input common-mode voltage range is −0.3 V to +3.2 V, and VOCM must be set between 1.0 V and 3.8 V to maintain linear operation. The −3 dB bandwidth reduces slightly to 310 MHz (typ), and slew rate drops to 950 V/µs, but key specs including 16 ns settling time and −90 dBc SFDR at 5 MHz remain valid per Table 3 of the Rev. G datasheet.

How does the VOCM pin function in AD8138AARMZ?

The VOCM pin on the AD8138AARMZ directly sets the common-mode voltage of both +OUT and −OUT terminals with a 1:1 ratio-e.g., 2.5 V applied to VOCM results in +OUT and −OUT dc bias levels centered at 2.5 V. This internal feedback mechanism operates independently of gain-setting resistors and remains effective across frequency (250 MHz −3 dB bandwidth for VOCM path), enabling precise level-shifting for single-supply ADCs without external components. The AD8138AARMZ VOCM input resistance is 200 kΩ (±5 V supply) or 100 kΩ (+5 V supply).

What is the minimum load impedance supported by AD8138AARMZ?

The AD8138AARMZ is characterized with differential load (RL,dm) down to 500 Ω (e.g., 1 kΩ per side), and its output current capability of ±95 mA supports heavier loads. Harmonic distortion degrades gradually with decreasing RL,dm: at 200 Ω, HD2 increases by ~3 dBc versus 800 Ω per Figure 17. For stable operation into capacitive loads, Analog Devices recommends limiting CL to ≤10 pF without series isolation; the AD8138AARMZ maintains 16 ns settling even with 1 pF CF per Table 1.

Is AD8138AARMZ pin-compatible with other members of the AD813x family?

Yes, the AD8138AARMZ shares identical pinout and footprint with AD8137 and AD8132 in the MSOP-8 package (e.g., AD8137ARMZ, AD8132ARMZ). However, performance differs significantly: AD8132 offers lower power (25 mW) but reduced bandwidth (350 MHz) and higher distortion (−75 dBc SFDR), while AD8137 lacks VOCM control. The AD8138AARMZ is the only variant with integrated VOCM and −94 dBc SFDR at 5 MHz, making it non-interchangeable despite mechanical compatibility.