Analog Devices Inc. AD9238BST-65

Overview

AD9238BST-65 from Analog Devices is a dual-channel, 12-bit, 65 MSPS analog-to-digital converter (ADC) with differential input architecture, integrated voltage reference, and clock duty cycle stabilizer. It delivers 70 dB SNR and 80.5 dBc SFDR at 32.5 MHz input, operates from a single 3 V supply (2.7–3.6 V), and consumes 600 mW total power. It is used in ultrasound front-ends and IF-sampling receivers requiring high channel isolation and low-power wideband digitization.

For engineers reviewing the AD9238BST-65 datasheet, AD9238BST-65 pinout, AD9238BST-65 application, or AD9238BST-65 equivalent, this page provides verified specifications, LQFP-64 pin mapping, dual-channel timing roles, crosstalk immunity (>85 dB), and validated alternatives for direct-conversion radio and battery-powered test equipment design.

Technical Context

The AD9238BST-65 implements a multistage differential pipelined ADC architecture with output error correction logic to guarantee no missing codes across −40°C to +85°C. Each channel features independent sample-and-hold amplifiers with 500 MHz 3 dB input bandwidth and configurable 1 V_p-p or 2 V_p-p full-scale range.

It supports dual single-ended clock inputs (CLK_A/CLK_B), clock duty cycle stabilization (DCS), flexible data formatting (offset binary or twos complement), and multiplexed output mode via MUX_SELECT. Channel isolation exceeds 85 dB at 10 MHz, and pipeline latency is fixed at 7 clock cycles.

Key Specifications

Pinout & Package

AD9238BST-65 is packaged in a Pb-free, 64-lead LQFP (10 mm × 10 mm, 0.5 mm pitch) with exposed pad connected to AGND. Pinout conforms to Figure 3 and Table 6 of Rev. D datasheet.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-channel ADC applications.

Compared with AD9238BCP-65, AD9238BST-65 offers identical electrical performance but simplified thermal management via LQFP's larger copper area; versus AD9248BST-65, it trades 2 bits of resolution for 150 mW lower power and 3.5 dB better SFDR-critical for communication receiver selectivity.

Availability

AD9238BST-65 is available at Aetrix Electronics and suitable for ultrasound equipment, IF-sampling receivers, and battery-powered test instruments requiring stable component supply and long-term industrial temperature support (−40°C to +85°C).

Supply support for AD9238BST-65 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 AD9238 product line delivers dual-channel, high-speed ADCs optimized for communications infrastructure, medical imaging, and portable instrumentation where channel matching, low power, and wide analog bandwidth are critical.

FAQ

What is the maximum analog input frequency supported by the AD9238BST-65?

The AD9238BST-65 has a 500 MHz (3 dB) differential analog input bandwidth, enabling undersampling of RF/IF signals far above its 65 MSPS Nyquist limit. At f_IN = 100 MHz, SNR remains 67.6 dB, confirming usability for first- or second-Nyquist zone sampling in direct-conversion receivers. The input structure uses 7 pF effective capacitance per pin, requiring impedance-matched layout for optimal HF performance.

Does the AD9238BST-65 require external voltage reference components?

No, the AD9238BST-65 integrates a precision 1.0 V voltage reference with ±35 mV output error over temperature and load regulation of 0.8 mV at 1.0 mA. It supports both internal reference mode (via SENSE pin) and external reference mode (using REFT/REFB pins). This eliminates external reference ICs, reducing BOM count and board area while maintaining 12-bit accuracy across −40°C to +85°C.

How does the clock duty cycle stabilizer (DCS) function in the AD9238BST-65?

The DCS circuit in the AD9238BST-65 actively corrects clock duty cycle deviations from 50%, maintaining SNR/SFDR performance across 30%–70% duty cycles. When enabled (DCS pin tied high), it eliminates need for precise clock buffer tuning-critical in FPGA-generated clock systems. Performance data (Figure 24) shows <0.5 dB SINAD degradation even at 35%/65% duty cycle, unlike DCS-disabled operation which degrades >3 dB.

Can the AD9238BST-65 operate with only one channel active?

Yes, the AD9238BST-65 supports independent channel power-down via PDWN_A and PDWN_B pins. Setting PDWN_A = 1 powers down Channel A (outputs held static), reducing total power from 600 mW to ~300 mW. This preserves full performance on the active channel-including SNR, SFDR, and crosstalk-making it ideal for applications like single-channel scopemeters or reconfigurable test equipment.

What is the pipeline latency of the AD9238BST-65 and how is it used in system timing?

The AD9238BST-65 has a fixed pipeline latency of 7 clock cycles from CLK edge to valid output data. This deterministic delay enables precise synchronization in time-critical systems such as ultrasound beamforming or digital predistortion loops. Latency is unaffected by input frequency, data format, or power-down state-allowing reliable timing budget allocation in FPGA-based controllers interfacing to AD9238BST-65.