LTC2181IUP - 16-Bit 40Msps Dual ADC, DDR LVDS | Analog Devices
MPN: LTC2181IUP ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $38.5 | $38.50 |
| 10 | $34.65 | $346.50 |
| 100 | $30.8 | $3,080.00 |
| 500 | $27.95 | $13,975.00 |
| 1,000 | $25.2 | $25,200.00 |
LTC2181IUP Overview
An ADC (Analog-to-Digital Converter) is a data converter that samples continuous analog voltage signals and produces discrete digital codes. Within the broader semiconductor hierarchy, the LTC2181IUP belongs to the high-speed ADC family, which is itself a sub-category of data converters, sitting alongside DACs (Digital-to-Analog Converters) and CODECs. High-speed pipeline ADCs like the LTC2181 are the workhorse of communications, test and measurement, and defense signal chains where wide analog bandwidth and high dynamic range are required.
Key features include integrated bypass capacitance to reduce PCB complexity, selectable input ranges of 1 Vp-p to 2 Vp-p, an internal duty-cycle stabilizer that corrects for clock duty-cycle distortion, and a low-jitter clock receiver that accepts CMOS, LVDS, or sine-wave inputs. Each channel is independently controlled via a 3-wire SPI-compatible serial interface, allowing per-channel gain, offset, and phase calibration without external trim. The 64-lead QFN package with an exposed pad provides a thermal resistance (theta_JC) suitable for the device's low 100 mW per channel power dissipation.
The LTC2181's pipelined architecture is built around 16 internal stages with error correction, and its DDR LVDS digital interface transmits two data bits per clock cycle, halving the number of required output traces and easing PCB routing. The combination of low jitter (< 70 fs), high SNR, and selectable LVDS swing (350 mV or 700 mV) makes it well suited for driving FPGAs and ASICs over short board-to-board links.
Typical applications include cellular base-station receive paths, multiband, multimode digital receivers, antenna array processing, communications test equipment, and high-end imaging systems such as medical ultrasound and non-destructive flaw detection. The dual simultaneous-sampling architecture is particularly important for I/Q demodulation and for any system that requires phase-coherent acquisition of two signals.
When designing with the LTC2181IUP, place the 1.8 V analog decoupling capacitors within 5 mm of the AVDD pins and bond the exposed pad to a clean ground plane to keep digital switching currents out of the analog return path. The DDR LVDS output timing is referenced to the rising clock edge; be sure to use the same source-matched impedance (100 ohm differential) on all data and clock pairs to avoid inter-symbol jitter.
This page synthesizes distributor pricing, drop-in same-family alternatives (LTC2180, LTC2182), and practical layout guidance that is not contained in the bare manufacturer datasheet.
Drop-in alternatives for LTC2181IUP — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with LTC2181IUP (same form factor and footprint) — differing in Package, Resolution, SNR, Operating Temperature Range, Number of Channels.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
LTC2182IUP
✅ Drop-In✓ In Stock
$105.93 / Unit
View Datasheet →LTC2180IUP
✅ Drop-In✓ In Stock
$48 / Unit
View Datasheet →LTC2180CUP
✅ Drop-In✓ In Stock
$41.72 / Unit
View Datasheet →LTC2155CUP-12
✅ Drop-In✓ In Stock
$44.25 / Unit
View Datasheet →LTC2156IUP-14
✅ Drop-In✓ In Stock
$134.1 / Unit
View Datasheet →LTC2144IUP-14
✅ Drop-In✓ In Stock
$60.15 / Unit
View Datasheet →LTC2181IUP Maximum Ratings & Electrical Characteristics
| Number of Bits | 16 |
| Sampling Rate | 40 Msps |
| Number of Channels | 2 (simultaneous sampling) |
| Architecture | Pipelined |
| Input Type | Differential |
| Selectable Input Range | 1 Vp-p to 2 Vp-p |
| Analog Supply Voltage | 1.8 V |
| Digital Output Interface | DDR LVDS |
| LVDS Swing Select | 350 mV or 700 mV |
| SNR (5 MHz input) | 77 dBFS |
| SFDR (5 MHz input) | 90 dBFS |
| Power Dissipation (per channel) | 100 mW |
| Operating Temperature | -40C to +85C |
| Package | 64-QFN (9x9 mm) with exposed pad |
| Clock Duty-Cycle Stabilizer | Yes (internal) |
| Configuration Interface | SPI-compatible serial |
LTC2181IUP Pin Configuration
| Pin 1 | GND — Ground |
| Pin 2 | INA+ — Channel A positive analog input |
| Pin 3 | INA- — Channel A negative analog input |
| Pin 4 | GND — Ground |
| Pin 5 | INB+ — Channel B positive analog input |
| Pin 6 | INB- — Channel B negative analog input |
| Pin 7 | GND — Ground |
| Pin 8 | AVDD — 1.8 V analog supply |
| Pin 9 | GND — Ground |
| Pin 10 | VCM — Common-mode voltage output |
| Pin 11 | AVDD — 1.8 V analog supply |
| Pin 12 | GND — Ground |
| Pin 13 | AVDD — 1.8 V analog supply |
| Pin 14 | SENSE — Voltage reference sense pin |
| Pin 15 | VREF — Voltage reference bypass |
| Pin 16 | GND — Ground |
| Pin 17 | OVDD — LVDS output driver supply |
| Pin 18 | GND — Ground |
| Pin 19 | CLK+ — Clock input positive |
| Pin 20 | CLK- — Clock input negative |
| Pin 21 | GND — Ground |
| Pin 22 | ENC+ — Encode clock positive (per datasheet) |
| Pin 23 | ENC- — Encode clock negative (per datasheet) |
| Pin 24 | GND — Ground |
| Pin 25 | OA0+ — Channel A LVDS data output bit 0 positive |
| Pin 26 | OA0- — Channel A LVDS data output bit 0 negative |
| Pin 27 | GND — Ground |
| Pin 28 | OA1+ — Channel A LVDS data output bit 1 positive |
| Pin 29 | OA1- — Channel A LVDS data output bit 1 negative |
| Pin 30 | GND — Ground |
| Pin 31 | OA2+ — Channel A LVDS data output bit 2 positive |
| Pin 32 | OA2- — Channel A LVDS data output bit 2 negative |
| Pin 33 | GND — Ground |
| Pin 34 | OA3+ — Channel A LVDS data output bit 3 positive |
| Pin 35 | OA3- — Channel A LVDS data output bit 3 negative |
| Pin 36 | GND — Ground |
| Pin 37 | OB0+ — Channel B LVDS data output bit 0 positive |
| Pin 38 | OB0- — Channel B LVDS data output bit 0 negative |
| Pin 39 | GND — Ground |
| Pin 40 | OB1+ — Channel B LVDS data output bit 1 positive |
| Pin 41 | OB1- — Channel B LVDS data output bit 1 negative |
| Pin 42 | GND — Ground |
| Pin 43 | OB2+ — Channel B LVDS data output bit 2 positive |
| Pin 44 | OB2- — Channel B LVDS data output bit 2 negative |
| Pin 45 | GND — Ground |
| Pin 46 | OB3+ — Channel B LVDS data output bit 3 positive |
| Pin 47 | OB3- — Channel B LVDS data output bit 3 negative |
| Pin 48 | GND — Ground |
| Pin 49 | FR+ — Frame output positive |
| Pin 50 | FR- — Frame output negative |
| Pin 51 | GND — Ground |
| Pin 52 | DCS+ — Duty-cycle stabilizer / data clock positive |
| Pin 53 | DCS- — Duty-cycle stabilizer / data clock negative |
| Pin 54 | GND — Ground |
| Pin 55 | CS — SPI chip select |
| Pin 56 | SCK — SPI serial clock |
| Pin 57 | SDI — SPI serial data input |
| Pin 58 | SDO — SPI serial data output |
| Pin 59 | GND — Ground |
| Pin 60 | OGND — Output driver ground |
| Pin 61 | OVDD — LVDS output driver supply |
| Pin 62 | GND — Ground |
| Pin 63 | AVDD — 1.8 V analog supply |
| Pin 64 | GND — Ground |
Typical Applications
LTC2181IUP is suitable for 6 applications: Cellular Base-Station Receive Path, Multiband Multimode Digital Receiver, Antenna Array Processing, Communications Test Equipment, Medical Ultrasound Imaging, Non-Destructive Flaw Detection.
Cellular Base-Station Receive Path
The LTC2181IUP's 77 dBFS SNR and 90 dBFS SFDR make it well suited for digitising multi-carrier LTE and 5G NR signals at the base-station antenna interface, where high dynamic range is required to detect weak users in the presence of strong in-band blockers. The dual simultaneous-sampling channels let designers capture two diversity or two polarisation paths with a single chip, halving board area versus a discrete dual-ADC design.
Recommended
Multiband Multimode Digital Receiver
The LTC2181IUP's 40 Msps sample rate is high enough to IF-sample signals in the 5-140 MHz range used by multiband software-defined radios, eliminating one or more downconversion stages. Its internal duty-cycle stabilizer tolerates non-50% clocks, and the 1.8 V single supply simplifies power-tree design. The dual channels let one chip serve as the I and Q paths of a complex mixer, reducing I/Q mismatch.
Recommended
Antenna Array Processing
Phased-array and MIMO systems demand phase-coherent multi-channel digitisation, and the LTC2181IUP's two simultaneous-sampling 16-bit channels provide the matched-channel acquisition needed for digital beamforming. With per-channel SPI gain and offset trim, the user can calibrate amplitude and phase mismatch in the digital domain. The 64-QFN package is small enough to place close to each antenna element, minimising analogue trace length.
Recommended
Communications Test Equipment
The 77 dBFS SNR, 90 dBFS SFDR, and selectable 1-2 Vp-p input range of the LTC2181IUP make it a strong fit for digitiser cards in spectrum analysers, signal generators, and production test racks. Its pipelined architecture delivers low latency suitable for closed-loop stimulus-response testing, and the DDR LVDS output feeds directly into FPGAs for real-time DSP such as FFT, demodulation, and EVM measurement.
Recommended
Medical Ultrasound Imaging
In medical ultrasound, each transducer channel requires a high-resolution, high-speed ADC, and the LTC2181IUP's two simultaneous-sampling channels let one IC service two transducer elements, halving the ADC count per probe. Its 16-bit resolution and low noise support the wide dynamic range needed to image both strong specular reflectors and subtle tissue echoes. The exposed-pad QFN package manages the modest 200 mW dissipation without a heatsink.
Recommended
Non-Destructive Flaw Detection
Industrial phased-array flaw detectors used in aerospace and pipeline inspection rely on the LTC2181IUP's dual simultaneous-sampling channels to capture transmit and receive echoes with matched timing, enabling accurate time-of-flight measurements. Its 40 Msps sample rate supports centre frequencies up to 20 MHz, and the 1.8 V supply rail simplifies battery-powered portable flaw detector designs used in the field.
Recommended
Recommended Products Summary
Engineering reference data for LTC2181IUP — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | LTC2182IUP | LTC2180IUP | LTC2180CUP | LTC2156IUP-14 | LTC2144IUP-14 |
|---|---|---|---|---|---|---|
| Package | 64-QFN (9x9 mm) | 64-QFN (9x9 mm) - same | 64-QFN (9x9 mm) - same | 64-QFN (9x9 mm) - same | 64-QFN (9x9 mm) - same | 64-QFN (9x9 mm) - same |
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Resolution | 16-bit | 16-bit | 16-bit | 16-bit | 14-bit | 14-bit |
| Sampling Rate | 40 Msps | 65 Msps | 25 Msps | 25 Msps | 80 Msps | 80 Msps |
| Number of Channels | 2 (simultaneous) | 2 (simultaneous) | 2 (simultaneous) | 2 (simultaneous) | 2 (simultaneous) | 2 (simultaneous) |
| Temperature Range | -40C to +85C (I grade) | -40C to +85C | -40C to +85C | 0C to +70C (C grade) | -40C to +85C | -40C to +85C |
Key Differentiators
- Pin-compatible 25/40/65 Msps family enables single PCB design for multiple products (vs LTC2180IUP / LTC2182IUP)
- Higher SNR and SFDR than 14-bit dual ADCs in the same package (vs LTC2156IUP-14 / LTC2144IUP-14)
- Industrial -40C to +85C temperature grade at no extra cost vs commercial grade (vs LTC2180CUP)
Design Notes
Place the 1.8 V analog decoupling capacitors (typically 10 uF bulk + 0.1 uF ceramic) within 5 mm of the AVDD pins and bond the exposed pad to a clean ground plane with at least 9 thermal vias. The DDR LVDS data and clock pairs should be routed as 100 ohm differential microstrip with matched lengths to within 2 mm to avoid inter-symbol jitter, and should be guarded by adjacent ground traces on each side of the differential pair.
The AVDD and DVDD pins must be powered from the same low-noise 1.8 V LDO regulator (e.g., Analog Devices ADP1761) to prevent supply-noise coupling between channels. The OVDD pin can be tied to a separate supply if the FPGA LVDS receiver operates at a different voltage (1.8 V or 2.5 V). Add a small ferrite bead between the LDO output and the OVDD pin to break the digital switching return-current path.
Do not leave the SENSE pin floating - tie it to AVDD for internal reference or to VREF for external reference operation. The duty-cycle stabilizer (DCS) should be enabled for non-50% duty cycle clocks and disabled only when the user is supplying a clean 50% duty cycle clock. The exposed pad must be soldered to the PCB ground plane; failure to do so violates the thermal specification and may cause intermittent LVDS link errors.
Estimated: aperture jitter of the LTC2181IUP is < 70 fs RMS per the datasheet 218210f; at 40 Msps with a 140 MHz full-scale input, this contributes roughly 1 LSB of SNR degradation. To stay within budget, drive the CLK+/CLK- pins with a low-jitter clock source such as the ADF4351 or AD9528, and avoid sharing clock buffers between ADC and high-speed digital outputs.
Compliance Information
RoHS and lead-free per Analog Devices product page and PBF suffix convention. Not AEC-Q100 qualified - this part targets industrial-grade communications, not automotive. Halogen-free status not stated in the verified data.
