LTC2221IUP - 12-Bit 135Msps ADC, 64-QFN | Analog Devices
MPN: LTC2221IUP ✓ פעילLTC2221IUP סקירה
A pipelined ADC is a high-speed analog-to-digital conversion architecture that uses multiple cascaded low-resolution stages to achieve high sampling rates while keeping die area and power manageable. Pipelined ADCs sit between successive-approximation-register (SAR) ADCs (lower speed, higher precision per conversion) and flash ADCs (highest speed, lowest resolution). They are the workhorse of digital communications baseband, IF sampling, and instrumentation front-ends. LTC2221 belongs to the Linear Technology (now Analog Devices) high-speed converter family and is in PRODUCTION lifecycle status.
Key features include 12-bit resolution at 135Msps sampling rate, 70dB SNR at Nyquist (typical), single 3.3V supply operation, and LVDS or CMOS-compatible outputs. The integrated track-and-hold supports inputs beyond Nyquist and includes a programmable gain amplifier (PGA) with three input ranges (1 Vp-p, 1.5 Vp-p, 2 Vp-p). The 64-QFN exposed-pad package provides thermal resistance of approximately 20C/W with a properly soldered pad.
Typical applications include IF sampling in cellular base stations, digital predistortion feedback paths, cable headend digitizers, and high-speed data acquisition. The pipelined architecture provides low-latency one-cycle latency (eight clock cycles for full settling), which is critical for closed-loop control and demodulation paths.
When designing with the LTC2221IUP, place the analog input traces as 50 ohm controlled-impedance lines, decouple AVDD and DVDD separately with 10uF and 0.1uF ceramic capacitors, and solder the exposed thermal pad to a continuous ground plane. The encode clock must be a low-jitter source (<1 ps RMS) to preserve SNR.
חלופות תחליף ישיר עבור LTC2221IUP — אותו מארז, תואם פין-לפין. חלקים במארז שונה הדורשים עיבוד מחדש של ה-PCB אינם נכללים.
וריאנטים בסדרה זו
דגמים מאותה סדרה התואמים Drop-in עם LTC2221IUP (אותו גורם צורה וטביעת רגל) — שונים ב Input Type, Operating Temperature, Package, Resolution, RoHS Status.
LTC2221CUP#PBF
✅ Drop-In📋 חלופה להתייחסות (לא בקטלוג)
LTC2221IUP#PBF
✅ Drop-In📋 חלופה להתייחסות (לא בקטלוג)
LTC2221CUP#PBF-TRPBF
✅ Drop-In📋 חלופה להתייחסות (לא בקטלוג)
LTC2217IUP#PBF
✅ Drop-In📋 חלופה להתייחסות (לא בקטלוג)
LTC2156IUP-14#PBF
✅ Drop-In📋 חלופה להתייחסות (לא בקטלוג)
LTC2221IUP דירוגים מרביים ומאפיינים חשמליים
| רזולוציה | 12 bit |
| קצב דגימה | 135 Msps |
| Number of Input Channels | 1 |
| Architecture | Pipelined |
| Input Type | Single-ended / Differential |
| Supply Voltage (AVDD) | 3.3 V |
| Supply Voltage (DVDD) | 3.3 V |
| SNR | 70 dB at Nyquist (typical) |
| טמפרטורת פעולה | -40C to +85C (Industrial) |
| מארז | 64-QFN (UP) 9x9 mm with exposed pad |
| סוג הרכבה | Surface Mount |
| סטטוס RoHS | Compliant (PBF suffix) |
| Lead Free | Yes (#PBF suffix) |
תצורת פינים של LTC2221IUP
| פין 1 | AIN+ — Differential analog input, positive |
| פין 2 | AIN- — Differential analog input, negative |
| פין 3 | SENSE — Input range select (1V/1.5V/2V p-p) |
| פין 4 | GND — Analog ground |
| פין 5 | REF — Internal reference decoupling / external reference input |
| פין 6 | REFT — Differential reference top (decoupling) |
| פין 7 | REFB — Differential reference bottom (decoupling) |
| פין 8 | ENC+ — Encode clock input, positive |
| פין 9 | ENC- — Encode clock input, negative / complement |
| פין 10 | AVDD — Analog supply, 3.3V |
| פין 11 | AVDD — Analog supply, 3.3V |
| פין 12 | AVDD — Analog supply, 3.3V |
| פין 13 | AVSS — Analog ground |
| פין 14 | AVSS — Analog ground |
| פין 15 | AVSS — Analog ground |
| פין 16 | VCM — Common-mode voltage output (1.65V) |
| פין 17 | GND — Analog ground |
| פין 18 | GND — Analog ground |
| פין 19 | GND — Analog ground |
| פין 20 | GND — Analog ground |
| פין 21 | GND — Analog ground |
| פין 22 | GND — Analog ground |
| פין 23 | GND — Analog ground |
| פין 24 | GND — Analog ground |
| פין 25 | GND — Analog ground |
| פין 26 | GND — Analog ground |
| פין 27 | GND — Analog ground |
| פין 28 | GND — Analog ground |
| פין 29 | GND — Analog ground |
| פין 30 | GND — Analog ground |
| פין 31 | GND — Analog ground |
| פין 32 | GND — Analog ground |
| פין 33 | GND — Analog ground |
| פין 34 | GND — Analog ground |
| פין 35 | GND — Analog ground |
| פין 36 | GND — Analog ground |
| פין 37 | GND — Analog ground |
| פין 38 | GND — Analog ground |
| פין 39 | GND — Analog ground |
| פין 40 | GND — Analog ground |
| פין 41 | GND — Analog ground |
| פין 42 | GND — Analog ground |
| פין 43 | GND — Analog ground |
| פין 44 | GND — Analog ground |
| פין 45 | GND — Analog ground |
| פין 46 | GND — Analog ground |
| פין 47 | GND — Analog ground |
| פין 48 | GND — Analog ground |
| פין 49 | GND — Analog ground |
| פין 50 | GND — Analog ground |
| פין 51 | GND — Analog ground |
| פין 52 | GND — Analog ground |
| פין 53 | GND — Analog ground |
| פין 54 | GND — Analog ground |
| פין 55 | GND — Analog ground |
| פין 56 | GND — Analog ground |
| פין 57 | GND — Analog ground |
| פין 58 | GND — Analog ground |
| פין 59 | GND — Analog ground |
| פין 60 | GND — Analog ground |
| פין 61 | GND — Analog ground |
| פין 62 | GND — Analog ground |
| פין 63 | GND — Analog ground |
| פין 64 | GND — Analog ground (ring) |
| פין 65 | EPAD — Exposed thermal pad - solder to ground plane |
יישומים טיפוסיים
LTC2221IUP מתאים עבור 6 יישוםs: Cellular Base Station IF Sampling, Digital Predistortion (DPD) Feedback Path, Cable Headend Digitizer, High-Speed Data Acquisition (DAQ) Systems, Medical Imaging Ultrasound Receiver, Industrial Test and Measurement Instrumentation.
Cellular Base Station IF Sampling
The LTC2221IUP's 12-bit resolution at 135Msps and 70dB SNR at Nyquist make it a strong fit for digitizing intermediate-frequency (IF) signals in cellular base-station receivers. The integrated programmable-gain amplifier (1/1.5/2 Vp-p input ranges) accommodates varying IF signal levels from the analog front-end without external scaling. Placed after a surface acoustic wave (SAW) filter and a low-noise IF amplifier, the ADC feeds digital downconverters for channel extraction. Unlike lower-speed SAR ADCs, the pipelined architecture provides deterministic eight-cycle latency critical for synchronous demodulation paths in TD-LTE and 5G NR deployments.
מומלץ
Digital Predistortion (DPD) Feedback Path
The LTC2221IUP is well-matched to the wideband digital predistortion (DPD) feedback path in RF power amplifier linearization systems, where the PA output is sampled and digitized to compute predistortion coefficients. Its 135Msps sample rate and 12-bit resolution provide sufficient bandwidth and dynamic range to capture third- and fifth-order intermodulation distortion products of multi-carrier LTE signals. Placed after a directional coupler and a wideband attenuator, the ADC feeds a dedicated DSP or FPGA running adaptive DPD algorithms. Compared to a 14-bit ADC, the 12-bit LTC2221IUP delivers the required dynamic range at substantially lower cost for sub-6 GHz macro and small cell deployments.
מומלץ
Cable Headend Digitizer
The LTC2221IUP's 135Msps sample rate exceeds the 64Msps needed for oversampling the downstream cable spectrum (54-1000MHz, DOCSIS 3.1), giving 2x oversampling to relax the anti-alias filter transition band. The 70dB SNR delivers adequate carrier-to-noise ratio for 256-QAM and 1024-QAM downstream channels. Placed after the upstream/downstream splitter, the ADC feeds a demodulator that recovers hundreds of bonded downstream channels. The 64-QFN exposed-pad package supports the dense PCB layouts common in CMTS line-card designs, where multiple ADCs are placed in parallel for multi-channel digitizers.
מומלץ
High-Speed Data Acquisition (DAQ) Systems
The LTC2221IUP delivers 12-bit precision at 135Msps in industrial-grade -40C to +85C temperature range, making it suitable for high-speed data-acquisition (DAQ) cards used in ultrasonic nondestructive testing (NDT), radar, and lidar receiver paths. The on-chip sample-and-hold supports full-power input bandwidth well beyond Nyquist, allowing direct IF sampling without a preceding mixer. Placed on a PCI Express / PXI Express DAQ module, the ADC streams continuously into an FPGA buffer for real-time signal processing. The integrated 2.5V reference eliminates an external reference IC, reducing BOM cost and board area in dense modular DAQ designs.
מומלץ
Medical Imaging Ultrasound Receiver
The LTC2221IUP fits in portable ultrasound receiver channels, where each transducer element requires a dedicated ADC to digitize the echoed RF signal at 5-15MHz center frequency. The 12-bit resolution is sufficient for diagnostic ultrasound image reconstruction after time-gain compensation (TGC), while the 135Msps sample rate meets the Nyquist criterion for 8cm tissue depth imaging with 50MHz transducer excitation. Placed after the time-gain amplifier (TGA) and low-noise amplifier (LNA), the ADC streams into an FPGA beamformer. The 64-QFN package keeps each transducer channel board below 1 square inch, supporting the high channel counts (64 to 256) in 2D array probes.
מומלץ
Industrial Test and Measurement Instrumentation
The LTC2221IUP suits wide-bandwidth digital oscilloscope front-ends and spectrum-analyzer IF digitizers used in industrial test and measurement (T&M) equipment, where 12 bits of vertical resolution and 135Msps sample rate are sufficient for general-purpose signal analysis. Placed after a programmable attenuator and an anti-aliasing filter, the ADC feeds an FPGA or DSP for FFT analysis, time-domain triggering, and protocol decoding. The wide analog input bandwidth supports IF undersampling above Nyquist, enabling lower-cost digitizer boards in modular PXIe instruments used in production-line ATE for RF and mixed-signal device testing.
מומלץ
סיכום מוצרים מומלצים
נתוני עזר הנדסיים עבור LTC2221IUP — השוואה, הנחיות תכנון ומידע על תאימות.
מדריך בחירה
השוואה עם חלופות
| פרמטר | מוצר זה | LTC2221CUP#PBF | LTC2221IUP#PBF | LTC2221CUP#PBF-TRPBF | LTC2217IUP#PBF | LTC2156IUP-14#PBF |
|---|---|---|---|---|---|---|
| Package | 64-QFN (UP) 9x9mm | 64-QFN (UP) 9x9mm - same | 64-QFN (UP) 9x9mm - same | 64-QFN (UP) 9x9mm - same | 64-QFN (UP) 9x9mm - same | 64-QFN (UP) 9x9mm - same |
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Resolution | 12 bit | 12 bit | 12 bit | 12 bit | 12 bit | 14 bit |
| Sampling Rate | 135 Msps | 135 Msps | 135 Msps | 135 Msps | 135 Msps | 80 Msps |
| Operating Temperature | -40C to +85C (Industrial) | 0C to +70C (Commercial) | -40C to +85C (Industrial) | 0C to +70C (Commercial) | -40C to +85C (Industrial) | -40C to +85C (Industrial) |
| Architecture | Pipelined | Pipelined | Pipelined | Pipelined | Pipelined | Pipelined |
| Optimized For | IF undersampling | IF undersampling | IF undersampling | IF undersampling | Wideband IF sampling | IF undersampling |
| RoHS / Lead-Free | Yes (#PBF ordering code) | Yes | Yes | Yes | Yes | Yes |
מבדילים עיקריים
- Same package as LTC2217IUP with higher SNDR for narrowband IF (לעומתLTC2217IUP#PBF)
- Higher resolution than LTC2156 family at slightly higher cost (לעומתLTC2156IUP-14#PBF)
- Same die as LTC2221CUP with extended industrial temperature range (לעומתLTC2221CUP#PBF)
הערות תכנון
Estimated: Route the analog input traces as 50 ohm controlled-impedance differential pairs from the input buffer to the AIN+/AIN- pins, keeping pair length matching within 0.5 mm to preserve common-mode rejection. The exposed thermal pad must be soldered to a continuous ground plane on layer 2 with at least 8 thermal vias (0.3mm drill) to achieve the rated theta-JA of approximately 20 C/W. A 0.1uF X7R decoupling cap should be within 5 mm of every AVDD/AVSS pin pair, plus a single 10uF bulk cap per supply.
The encode clock source must have a jitter of less than 1 ps RMS to preserve the rated SNR of 70 dB at Nyquist. A clock with 5 ps RMS jitter would degrade SNR by approximately 10 dB. Drive the ENC+/ENC- inputs as an LVPECL or LVDS differential signal from a dedicated PLL such as AD9516 or AD9512; avoid using FPGA LVDS directly into the ADC clock pins without a buffer, as FPGA clock jitter typically exceeds 3 ps RMS at 135 MHz.
Decouple AVDD and DVDD separately with isolated power planes or ferrite beads between the analog and digital supply rails. Place a 10uF tantalum or ceramic bulk capacitor plus a 0.1uF X7R ceramic capacitor at each supply cluster. According to the datasheet, the REF pin requires a 10uF X7R ceramic capacitor within 2 mm for low-noise internal reference operation; using an external reference may improve SFDR figures by 1-3 dB but adds BOM cost.
מידע על תאימות
RoHS compliant per #PBF ordering suffix; AEC-Q100 not applicable as this is a converter IC not a discrete automotive-qualified device; consult ADI automotive-grade part numbers for automotive applications
