Analog Devices Inc. LTC2157CUP-12#PBF

Overview

LTC2157CUP-12#PBF from Analog Devices (formerly Linear Technology) is a dual-channel, 12-bit, 250Msps analog-to-digital converter optimized for high-frequency undersampling in communications and instrumentation systems. It delivers 68.5dB SNR, 90dB SFDR, 1.25GHz full-power bandwidth, DDR LVDS outputs, and operates from a single 1.8V supply. It is used in cellular basestations for wideband RF digitization.

For engineers reviewing the LTC2157CUP-12#PBF datasheet, LTC2157CUP-12#PBF pinout, LTC2157CUP-12#PBF application, or LTC2157CUP-12#PBF equivalent, key selection criteria include sampling rate tolerance at 250Msps, 1.5VP-P differential input drive compatibility, DDR LVDS output current programmability (1.75mA/3.5mA), and support for clock duty cycle stabilization in demanding RF front-end designs.

Technical Context

The LTC2157CUP-12#PBF implements a pipelined ADC architecture with integrated sample-and-hold (S/H) and correction logic per channel, enabling 6-cycle pipeline latency and <0.15psRMS acquisition jitter. Its 1.25GHz S/H bandwidth supports high-IF and direct-RF sampling up to 907MHz while maintaining >67dB SNR.

Dual independent 12-bit conversion paths feed DDR LVDS output drivers with on-chip 100Ω termination, configurable output current (1.75mA or 3.5mA), and programmable CLKOUT phase delay. Serial SPI interface (CS/SCK/SDI/SDO) enables runtime configuration of sleep/nap modes, duty cycle stabilizer, and LVDS drive strength.

Key Specifications

Pinout & Package

64-lead (9mm × 9mm) plastic QFN package with exposed thermal pad (Pin 65 = 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 12-bit high-speed ADC applications.

Compared with AD9233BCPZ-250 and LTC2267IUJ-12#PBF, the LTC2157CUP-12#PBF uniquely integrates dual 250Msps channels with 1.25GHz bandwidth and DDR LVDS in a single QFN, eliminating inter-device skew and simplifying layout for RF-sampling systems requiring >200MHz instantaneous bandwidth.

Availability

LTC2157CUP-12#PBF is available at Aetrix Electronics and suitable for cellular basestation receiver design, software-defined radio development, medical ultrasound beamforming, and high-speed test equipment requiring stable component supply across production lifecycles.

Supply support for LTC2157CUP-12#PBF 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 acquired Linear Technology in 2017 and maintains its high-performance signal chain portfolio, emphasizing precision, speed, and power efficiency in data converters and RF components.

The LTC2157 family belongs to Linear's ultra-high-speed ADC product line, designed specifically for demanding communications infrastructure and instrumentation applications requiring wide input bandwidth, low distortion, and deterministic latency.

FAQ

What is the operating temperature range for the LTC2157CUP-12#PBF?

The LTC2157CUP-12#PBF is specified for commercial-grade operation from 0°C to 70°C. This is indicated by the "C" suffix in the part number and confirmed in the Absolute Maximum Ratings table, where LTC2157C denotes the 0°C to 70°C range. The device uses internal thermal protection and is rated for continuous operation within this ambient range under recommended supply and load conditions.

Does the LTC2157CUP-12#PBF support both internal and external voltage references?

Yes, the LTC2157CUP-12#PBF supports both reference modes. Connecting the SENSE pin to VDD selects the internal 1.25V reference and a ±0.75V input range. Applying an external reference between 1.2V and 1.3V to SENSE configures a ±0.6 × VSENSE input range. The VREF pin outputs the internal reference voltage and must be bypassed with a 2.2µF ceramic capacitor.

How is the DDR LVDS output data organized on the LTC2157CUP-12#PBF?

The LTC2157CUP-12#PBF organizes DDR LVDS output per channel using six differential pairs: DA0_1 through DA10_11 for Channel A and DB0_1 through DB10_11 for Channel B. Each pair carries two time-multiplexed bits - even-indexed bits (e.g., DA0, DA2) appear when CLKOUT+ is low, and odd-indexed bits (e.g., DA1, DA3) appear when CLKOUT+ is high - achieving double-data-rate transmission.

Can the LTC2157CUP-12#PBF operate with an asymmetric encode clock?

Yes, the LTC2157CUP-12#PBF includes an optional clock duty cycle stabilizer that corrects duty cycle errors in the ENC+/ENC– input. When enabled via SPI register, it allows high-performance operation even with clocks exhibiting 40%–60% duty cycle variation, which is critical when using non-50% clocks from PLLs or crystal oscillators at 250Msps.

What power-saving modes does the LTC2157CUP-12#PBF offer, and how much power do they consume?

The LTC2157CUP-12#PBF offers Nap mode (181mW at 250Msps) and Sleep mode (<5mW with clock disabled). Nap mode retains configuration and bias states for fast wake-up; Sleep mode shuts down most circuitry except basic control logic. Both are controlled via SPI or parallel pins (CS/SCK in PAR/SER = VDD mode), enabling dynamic power scaling in portable or thermally constrained instruments.