Analog Devices Inc. AD9218BST-105

Overview

AD9218BST-105 from Analog Devices is a dual 10-bit, 105 MSPS analog-to-digital converter with on-chip track-and-hold and internal reference, designed for high-fidelity I/Q sampling in communications receivers and ultrasound front-ends. It delivers 57 dB SNR at 41 MHz input with 300 MHz analog bandwidth per channel, operates from a single 3.0 V supply (2.7–3.6 V), and supports 1 V_p-p or 2 V_p-p differential analog input ranges.

For engineers reviewing the AD9218BST-105 datasheet, AD9218BST-105 pinout, AD9218BST-105 application, or AD9218BST-105 equivalent, key selection considerations include its dual-channel interleaving capability, –75 dBc inter-channel crosstalk, user-selectable twos complement/offset binary output format, and compatibility with low-jitter 105 MSPS clock sources for direct IF sampling architectures.

Technical Context

The AD9218BST-105 implements a bit-per-stage pipeline ADC architecture with switch-capacitor techniques, delivering 7 MSBs per stage plus a 3-bit flash sub-converter. Each channel features independent differential analog inputs with self-biased common-mode voltage (V_D/3) and supports dc- or ac-coupled operation via external drivers like the AD8138.

Its digital interface uses TTL/CMOS-compatible outputs powered from a separate V_DD rail (2.5–3.6 V), enabling direct interfacing with 2.5 V or 3.3 V logic. User-selectable S1/S2 pins configure power-down modes (both channels or Channel B only) and data alignment-enabling synchronized dual-channel output on a single clock edge when enabled.

Key Specifications

Pinout & Package

AD9218BST-105 is housed in a 48-lead LQFP package (7 mm × 7 mm, 0.5 mm pitch), rated for industrial temperature range (–40°C to +85°C).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-channel, 10-bit, high-speed ADC applications.

Compared with AD9218BST-80 and AD9288BSTZ-100, the AD9218BST-105 uniquely delivers 10-bit resolution at 105 MSPS with guaranteed 57 dB SNR at 41 MHz-making it the sole option among these three for high-fidelity direct IF sampling where both speed and quantization accuracy are simultaneously critical.

Availability

AD9218BST-105 is available at Aetrix Electronics and suitable for ultrasound beamforming, I/Q communications receivers, handheld scopemeters, and battery-powered spectrum analyzers requiring stable component supply across industrial temperature ranges.

Supply support for AD9218BST-105 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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, founded in 1965 and headquartered in Wilmington, MA.

The AD9218 product line was engineered specifically for high-speed, dual-channel data acquisition in communications, medical imaging, and test equipment-emphasizing low power, integrated references, and pin-compatible scalability across speed grades.

FAQ

What is the maximum analog input frequency supported by the AD9218BST-105 without significant amplitude roll-off?

The AD9218BST-105 has a specified full-power analog bandwidth of 300 MHz, meaning it maintains ≥–3 dB response up to that frequency. This allows faithful digitization of wideband signals such as 51 MHz IF carriers in cable modems or broadband ultrasound echoes, provided the input driver (e.g., AD8138) and PCB layout preserve signal integrity through the 300 MHz range. The AD9218BST-105 achieves this using fully differential switched-capacitor front-end architecture with optimized input capacitance (3 pF) and resistance (10 kΩ).

Does the AD9218BST-105 require an external reference voltage, or can it operate using its internal reference?

The AD9218BST-105 can operate fully autonomously using its internal 1.24 V reference (pin REFOUT), which is routed to REFINA and REFINB to set the full-scale input range. No external reference is needed for standard operation. However, the reference inputs accept external sources (±5% tolerance) for custom scaling-e.g., adjusting full-scale range to match specific sensor output levels-without degrading SNR or linearity. The AD9218BST-105's internal reference exhibits 40 ppm/°C drift, ensuring stability over the industrial temperature range.

How does the data alignment mode work on the AD9218BST-105, and when should it be enabled?

Data alignment mode (enabled by setting S1=1, S2=1) delays Channel B's output by ½ clock cycle so both Channel A and Channel B data appear aligned on the rising edge of Clock A. This is essential when feeding dual-channel data into a single FIFO or DSP core that expects time-synchronized samples. It eliminates inter-channel timing skew in systems using a single clock source, avoiding post-processing interpolation. The AD9218BST-105 implements this via internal pipeline delay control-not external logic-ensuring deterministic 0.5-cycle alignment across temperature and voltage.

What power supply sequencing is required for reliable startup of the AD9218BST-105?

No strict power supply sequencing is mandated for the AD9218BST-105: VD (analog supply) and VDD (digital supply) may be ramped simultaneously or in either order within their specified ranges (2.7–3.6 V). The device incorporates internal power-on reset circuitry that holds outputs in high-impedance state until supplies stabilize. However, best practice is to ensure both rails reach nominal voltage before applying the ENCA/ENCB clock, as premature clocking during supply ramp-up may cause metastability. The AD9218BST-105 draws 175–188 mA from VD at 105 MSPS, requiring adequate decoupling (e.g., 10 µF bulk + 0.1 µF ceramic per supply pin).

Can the AD9218BST-105 be used in single-channel mode to reduce power consumption, and how is this configured?

Yes-the AD9218BST-105 supports true single-channel operation via its S1/S2 control pins. Setting S1=0, S2=1 powers down Channel B only, reducing total power by ~275 mW while keeping Channel A fully functional with all features (track-and-hold, reference, output drivers). In this mode, Channel B's analog inputs and digital outputs enter high-impedance states, eliminating switching noise coupling. Recovery from power-down takes exactly 10 clock cycles, as specified in the AD9218BST-105 datasheet, enabling rapid channel activation for burst-mode acquisition.