Analog Devices Inc. DC1532A-H

Overview

LTC2268-12 from Analog Devices (formerly Linear Technology) is a 12-bit, dual-channel, simultaneous-sampling analog-to-digital converter optimized for high-frequency communications signal digitization. It delivers 70.6dB SNR, 88dB SFDR, and ultralow 0.15ps_RMS aperture jitter at 125Msps sampling rate, with full-power bandwidth of 800MHz and single 1.8V supply operation - enabling direct IF sampling in cellular base stations and software-defined radios.

For engineers reviewing the LTC2268-12 datasheet, LTC2268-12 pinout, LTC2268-12 application, or LTC2268-12 equivalent, key selection considerations include its serial LVDS output architecture (1- or 2-lane mode), differential encode input flexibility (LVDS/PECL/TTL/CMOS), internal clock duty cycle stabilizer, and QFN-40 package thermal performance for high-density RF front-end designs.

Technical Context

The LTC2268-12 integrates two independent 12-bit ADC cores with shared PLL-based sampling clock generation and a digital serializer that outputs serialized LVDS data per channel. Its sample-and-hold stage supports 800MHz full-power bandwidth and operates with <0.3LSB_RMS transition noise and ±0.3LSB typical INL over temperature.

Digital interface includes SPI-configurable modes via CS/SCK/SDI/SDO pins and parallel programming via PAR/SER-selectable logic inputs. The device supports shutdown and nap modes (1mW and 70mW power states), selectable 1VP–P to 2VP–P input range, and internal/external reference configuration via SENSE pin.

Key Specifications

Pinout & Package

40-lead (6mm × 6mm) plastic QFN package with exposed thermal pad (Pin 41 = GND). Requires soldering of exposed pad to PCB ground plane for thermal and electrical integrity.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD9233-125 and LTC2267-12, the LTC2268-12 uniquely delivers guaranteed simultaneous dual-channel sampling at 125Msps in a single QFN-40 package - eliminating interleave calibration overhead while maintaining 70.6dB SNR and 0.15ps_RMS jitter critical for coherent RF systems.

Availability

LTC2268-12 is available at Aetrix Electronics and suitable for cellular infrastructure, software-defined radio development, and portable medical imaging systems requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for LTC2268-12 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 communications, industrial, automotive, and healthcare markets.

The LTC2268-12 belongs to ADI's high-speed precision ADC product line, designed specifically for demanding RF and IF digitization applications where dynamic range, jitter, and power efficiency must coexist in compact form factors.

FAQ

What is the maximum sampling rate supported by the LTC2268-12?

The LTC2268-12 supports a maximum sampling rate of 125Msps, validated across temperature and process corners. This rate is achievable in both 1-lane and 2-lane LVDS output modes, with serial data rates constrained to ≤1000Mbps - meaning tSER ≥ 1ns. At 125Msps, the device maintains 70.6dB SNR and 88dB SFDR with 0.15ps_RMS aperture jitter, making it suitable for direct IF sampling in LTE and 5G NR sub-6GHz front ends.

Does the LTC2268-12 support external reference configuration?

Yes, the LTC2268-12 supports both internal and external reference modes via the SENSE pin. When SENSE is tied to GND, the device operates with an external reference applied to the REFH/REFL pins, enabling user-defined input ranges from ±0.625V to ±1.3V. In this mode, the device achieves ±0.3LSB typical INL and 0.3LSB_RMS transition noise, preserving accuracy across the selected range.

How does the PAR/SER pin affect the functionality of CS, SCK, SDI, and SDO on the LTC2268-12?

When PAR/SER = GND, the LTC2268-12 enters serial programming mode: CS, SCK, SDI, and SDO form a standard 4-wire SPI interface for configuring registers. When PAR/SER = VDD, it enters parallel programming mode: CS selects 1-/2-lane output, SCK selects LVDS current (1.75mA/3.5mA), SDI enables shutdown, and SDO enables internal 100Ω termination - all controlled by static logic levels, not clocked sequences.

What thermal management guidance applies to the LTC2268-12 QFN package?

The LTC2268-12 uses a 40-lead 6mm × 6mm QFN with exposed thermal pad (Pin 41). This pad must be soldered directly to a solid PCB ground plane using ≥6 thermal vias (0.3mm diameter, spaced ≤1mm apart) to achieve θ_JA = 32°C/W. Failure to properly thermally attach the pad risks junction temperature exceeding 150°C at full 292mW dissipation, potentially degrading SNR and accelerating parametric drift.

Can the LTC2268-12 interface directly with Xilinx or Intel FPGAs without level-shifting?

Yes, the LTC2268-12's LVDS outputs (OUT1A+/–, OUT1B+/–, OUT2A+/–, OUT2B+/–) are fully compliant with ANSI TIA/EIA-644-A LVDS standards and operate at 1.8V OVDD. They interface natively with Xilinx Artix-7/Kintex-7 and Intel Cyclone V/Arria 10 FPGA LVDS I/O banks configured for 1.8V VCCIO, requiring no external level shifters or terminations beyond the FPGA's internal 100Ω differential termination.