Analog Devices Inc. DC2459A-B

Overview

DC2459A-B from Analog Devices (formerly Linear Technology) is a 16-bit, 50Msps differential current-output DAC evaluation board designed to demonstrate the LTC1668 high-speed digital-to-analog converter. It supports full-scale output currents up to 10mA, delivers 87dB SFDR at 1MHz f_OUT, features 5pV·s differential glitch impulse, 20ns settling time, and operates from ±5V supplies. It is used for RF waveform synthesis in cellular base stations and automated test equipment.

For engineers reviewing the DC2459A-B datasheet, DC2459A-B pinout, DC2459A-B application, or DC2459A-B equivalent, this page provides verified layout-validated performance data, transformer-coupled AC characterization setup details, IREFIN/REFOUT biasing guidance, LADCOM grounding best practices, and differential vs. single-ended output trade-offs confirmed in LTC1668 G01–G09 plots.

Technical Context

The DC2459A-B implements the LTC1668 in a fully populated, impedance-controlled 4-layer PCB layout optimized for high-frequency DAC evaluation. It integrates the 28-pin SSOP LTC1668 with matched 52.3Ω termination resistors on both IOUT A and IOUT B, Mini-Circuits T1-1T 1:1 RF transformer coupling, and dedicated COMP1/COMP2 bypassing per Figure 1 and Figure 5 of the LTC1668 datasheet.

It supports external reference operation via RSET (2kΩ default), accommodates TTL/CMOS 3.3V or 5V logic inputs, and maintains ±1V output compliance across IOUT A/IOUT B. The board's design enforces strict analog/digital ground separation (AGND/DGND), low-inductance REFOUT decoupling (0.1µF), and sub-100ps clock skew between CLK and DB15–DB0 signals - all validated in the LTC1668 timing diagram (TD) and AC characterization setup (F05).

Key Specifications

Availability

DC2459A-B is available at Aetrix Electronics and suitable for RF signal generation, high-speed instrumentation, wireless communications prototyping, and automated test equipment development requiring stable component supply and production-ready evaluation infrastructure.

Supply support for DC2459A-B 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. (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing technologies, serving precision instrumentation, communications, and industrial markets.

The DC2459A-B belongs to ADI's Linear Technology legacy evaluation board portfolio, specifically engineered to validate the dynamic and DC performance of the LTC1666/LTC1667/LTC1668 family of high-speed current-steering DACs in real-world RF and broadband applications.

FAQ

What is the primary function of the DC2459A-B evaluation board?

The DC2459A-B evaluation board is a fully assembled, application-validated platform for evaluating the LTC1668 16-bit, 50Msps differential current-output DAC. It enables rapid characterization of SFDR, THD, glitch impulse, and settling behavior under real operating conditions-including transformer-coupled outputs, internal/external reference configurations, and ±5V supply operation-without requiring custom PCB design. The DC2459A-B directly implements the recommended layout and decoupling from the LTC1668 datasheet.

Does the DC2459A-B support both internal and external reference modes for the LTC1668?

Yes, the DC2459A-B supports both internal and external reference operation for the LTC1668. By default, it uses the internal 2.5V bandgap reference with RSET = 2kΩ to set IOUTFS = 10mA. An external reference can be connected to the IREFIN pin by removing the RSET jumper and routing the reference voltage through appropriate series resistance, as shown in Figure F02 of the LTC1668 datasheet. All required REFOUT, COMP1, and COMP2 bypass capacitors are pre-installed on the DC2459A-B.

What output termination and coupling options are implemented on the DC2459A-B?

The DC2459A-B implements differential transformer-coupled output using a Mini-Circuits T1-1T 1:1 RF transformer with 50Ω double termination (50Ω on each IOUT leg plus 110Ω center-tap load). It also provides direct resistor-loaded differential output pads (52.3Ω per leg) and uncommitted IOUT A/IOUT B test points for op-amp I-to-V conversion. The board's layout preserves the ±1V output compliance range and minimizes common-mode noise coupling-critical for achieving the 87dB SFDR specified for the LTC1668.

How does the DC2459A-B ensure signal integrity for 50Msps operation?

The DC2459A-B ensures signal integrity for 50Msps operation through controlled-impedance routing (50Ω differential), tight length matching between CLK and DB15–DB0 traces (<5ps skew), separate AGND/DGND planes tied at a single point near the LTC1668, and localized 0.1µF ceramic bypassing at every power pin (VDD, VSS, REFOUT, COMP1, COMP2). These design choices directly implement the layout guidelines in the LTC1668 datasheet and enable verified 20ns settling and <8ps propagation delay (t_PD) performance.

Can the DC2459A-B be used to evaluate lower-resolution variants like the LTC1666 or LTC1667?

No-the DC2459A-B is specifically configured for the LTC1668 (16-bit, DB15–DB0 interface) and is not compatible with the LTC1666 (12-bit, DB11–DB0) or LTC1667 (14-bit, DB13–DB0) without hardware modification. Pinouts differ: the LTC1666 uses pins 27–28 and 1–10 for DB11–DB0; the LTC1667 uses pins 27–28 and 1–12 for DB13–DB0; only the LTC1668 uses pins 27–28 and 1–14 for DB15–DB0. The DC2459A-B's silkscreen, footprint, and routing are fixed for the 16-bit variant and cannot accommodate the different data bus widths or pin allocations of the other family members.