Analog Devices Inc. DC996B-B

Overview

LTC2208 from Analog Devices (acquired Linear Technology) is a 16-bit, 130Msps analog-to-digital converter optimized for high-frequency, wide-dynamic-range signal digitization up to 700MHz full-power bandwidth. It features a programmable gain amplifier (PGA) front end, 70fsRMS aperture jitter, 78dBFS noise floor, and 100dB spurious-free dynamic range (SFDR), making it suitable for cellular base station receivers and spectrum analysis equipment.

For engineers reviewing the LTC2208 datasheet, LTC2208 pinout, LTC2208 application, or LTC2208 equivalent, key selection considerations include its dual LVDS/CMOS output flexibility, internal clock duty cycle stabilizer, PGA-selectable input ranges (1.5VP-P or 2.25VP-P), and compatibility with undersampling architectures requiring ultra-low jitter timing performance.

Technical Context

The LTC2208 employs a 16-bit pipelined ADC core with integrated sample-and-hold and PGA front end, supporting differential analog inputs up to 700MHz. Its architecture enables undersampling of RF signals while maintaining 78dBFS SNR at 5MHz and >83dB SFDR at 250MHz with 1.5VP-P input range.

Digital outputs are configurable as standard or low-power LVDS (100Ω terminated) or single-ended CMOS (full-rate or demultiplexed), with separate OVDD supply (0.5V–3.6V) enabling voltage-level adaptation. Clock interface accepts differential (LVDS/PECL) or single-ended (TTL/CMOS) inputs, and optional internal dither improves SFDR by up to 10dB at –25dBFS.

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 high-speed ADC applications.

Compared with AD9653BCPZ-125 and LTC2268IUP-14, the LTC2208 delivers superior SFDR (100dB vs 85–90dB) and integrated PGA flexibility, justifying its use in demanding communications and instrumentation where signal fidelity and input dynamic range are critical.

Availability

LTC2208 is available at Aetrix Electronics and suitable for cellular infrastructure, spectrum analysis, and high-speed ATE requiring stable component supply with guaranteed long-term availability and traceable sourcing.

Supply support for LTC2208 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 LTC2208 belongs to ADI's high-speed ADC product line, designed specifically for RF/IF digitization in wireless infrastructure, defense electronics, and automated test equipment where wide bandwidth, low jitter, and high linearity are mandatory.

FAQ

What is the maximum analog input frequency supported by the LTC2208?

The LTC2208 supports a full-power analog input bandwidth of 700MHz, enabling direct RF sampling of signals up to this frequency. This specification is measured with RS < 25Ω source impedance and applies across the device's operating temperature range. The LTC2208 maintains usable SNR and SFDR performance well into the UHF band, making it suitable for undersampling architectures in cellular and radar applications.

Does the LTC2208 require an external reference voltage?

No, the LTC2208 includes an internal 2.5V bandgap reference. The SENSE pin (Pin 1) can be tied to VDD to activate it, setting a full-scale ADC range of 2.25VP-P (PGA = 0). Alternatively, an external 2.5V or 1.25V reference may be applied to SENSE for improved stability or system-level reference synchronization - both yield identical full-scale ranges.

How does the PGA pin affect the LTC2208's input range and performance?

The PGA pin (Pin 64) selects between two differential input ranges: logic low configures 2.25VP-P (1× gain), and logic high configures 1.5VP-P (1.5× gain). This adjusts front-end scaling to match signal amplitude - higher gain improves SNR for small signals but reduces headroom. Performance metrics like SNR and SFDR are specified for both settings, with 1.5VP-P mode showing slightly better SFDR at high input frequencies.

Can the LTC2208 operate with a single 3.3V supply?

Yes, the LTC2208 operates from a single 3.3V analog supply (VDD = 3.135V to 3.465V) and supports independent output supply (OVDD) from 0.5V to 3.6V. This allows interfacing with diverse logic families (e.g., 1.8V or 2.5V FPGAs) without level shifters. Total power dissipation is 1.25W in CMOS mode and ~1.5W in standard LVDS mode.

What is the purpose of the RAND pin on the LTC2208?

The RAND pin (Pin 63) enables digital output randomization: when asserted high, it XORs D1–D15 with D0 (LSB), scrambling the output pattern to reduce deterministic electromagnetic interference (EMI) from repetitive digital waveforms. The original data can be recovered by reapplying the same XOR operation at the receiver, preserving data integrity while lowering radiated emissions.