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Analog Devices Inc. LTC6955IUKG#PBF
- Part No.:
- LTC6955IUKG#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 52-WFQFN Exposed Pad
- Datasheet:
-
LTC6955IUKG#PBF.pdf
- Description:
- IC FANOUT BUFFER 52QFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,871
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Product details
Overview
LTC6955IUKG#PBF from Analog Devices is an ultralow-jitter, 7.5 GHz, 11-output CML clock buffer with parallel control for output enable/inversion and full shutdown. It delivers 45 fs RMS additive jitter (ADC SNR method), ±25 ps max skew across outputs, and operates from –40°C to 125°C. It is used in high-speed data converter clocking where phase noise directly limits effective resolution.
For engineers reviewing the LTC6955IUKG#PBF datasheet, LTC6955IUKG#PBF pinout, LTC6955IUKG#PBF application, or LTC6955IUKG#PBF equivalent, key selection criteria include its 7.5 GHz bandwidth, 45 fs RMS jitter at 7.5 GHz, 11 differential CML outputs with programmable polarity, 52-lead QFN package, and support for JESD204B subclass 1 SYSREF when paired with LTC6955-1.
Technical Context
The LTC6955IUKG#PBF implements a low-noise, fully buffered distribution path with self-biased 250 Ω differential input impedance and eleven independent 2.5 V CML output drivers. Each output supports DC-to-7.5 GHz operation with 320–550 mVP-P swing into 100 Ω differential termination.
Its 4-bit parallel SEL port enables dynamic configuration of 3–11 active outputs and per-output polarity inversion without requiring serial interface logic. The FILT pin selects internal broadband filtering for low-slew-rate inputs (<2 V/ns), improving phase noise floor by up to 8.8 dBc/Hz at 10 kHz offset.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Max Output Frequency | 7.5 GHz - supports direct clocking of 16-bit+ ADCs sampling at ≥3 GSPS without external frequency multiplication. |
| Additive RMS Jitter (ADC SNR) | 45 fs - translates to theoretical SNR limit of ~72.5 dBFS for a 1 GHz full-scale sine wave sampled at 7.5 GHz. |
| Output Skew (All Outputs) | ±25 ps (max, same part) - ensures sub-0.1° phase alignment error across all 11 outputs at 7.5 GHz for coherent multi-channel sampling. |
| Input Frequency Range | DC to 7.5 GHz - accepts direct RF oscillator inputs (e.g., Crystek CCHD-575-25-100) without intermediate buffering or level shifting. |
| Supply Voltage Range | 3.15 V to 3.45 V - tight 3.3 V ±4.5% tolerance enables stable operation with standard LDOs and reduces supply-induced jitter coupling. |
| Operating Temperature | –40°C to 125°C - qualified for industrial and base station RF front-end timing where ambient temperature exceeds 85°C. |
| Package | 52-lead 7 mm × 8 mm plastic QFN - exposed pad provides <2°C/W thermal resistance for continuous 420 mA output-stage current dissipation. |
Pinout & Package
52-lead plastic QFN (7 mm × 8 mm), exposed ground pad (Pin 53). Requires soldering of exposed pad to PCB ground plane with ≥9 thermal vias for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| IN+, IN– (37, 38) | Differential Clock Input | Self-biased 250 Ω differential input; accepts LVPECL/CML/LVDS or AC-coupled RF sine up to 7.5 GHz. |
| OUT0+ to OUT10+ / – (3–4, 6–7, 9–10, 12–13, 15–16, 18–19, 21–22, 24–25, 27–28, 30–31, 33–34) | Differential CML Outputs | Eleven 2.5 V CML drivers; each requires 100 Ω differential termination; supports polarity inversion via SEL bits. |
| SEL0–SEL3 (50–52, 1) | Parallel Output Control | 4-bit code selects 3–11 active outputs and enables inversion on odd-numbered outputs (OUT1, OUT3, etc.). |
| FILT (40) | Input Noise Filter Enable | Tie to V+ for <2 V/ns inputs to suppress broadband noise; tie to GND for ≥2 V/ns to avoid degrading phase noise. |
| VIN+, VD+, VOUT+ (39, 2, 5/8/11/14/17/20/23/26/29/32/35) | Separate Supply Rails | Independent 3.3 V supplies for input stage, control logic, and each output bank-minimizes crosstalk and improves PSRR. |
| GND (41, 53) | Signal & Thermal Ground | Pin 41 is signal ground; Pin 53 is exposed thermal pad-both must connect to low-inductance ground plane. |
Key Features
| Feature | Design Value |
|---|---|
| Ultralow additive jitter | 45 fs RMS (ADC SNR method) at 7.5 GHz input - preserves ENOB in high-resolution ADCs beyond 14 bits. |
| Programmable output count & polarity | 3–11 outputs enabled via 4-bit SEL port; odd outputs invert automatically - eliminates need for external inverters in top/bottom board routing. |
| Independent supply domains | VIN+, VD+, and 11× VOUT+ pins - isolates input, logic, and output noise sources to prevent supply coupling into clock paths. |
| Input slew-rate adaptive filtering | FILT pin toggles internal broadband filter - improves phase noise floor by >8 dBc/Hz at 10 kHz offset for low-slew inputs (<2 V/ns). |
| Industrial temperature range | –40°C to 125°C junction - enables deployment in outdoor wireless infrastructure and radar systems without derating. |
Applications
| High-Speed Data Acquisition | JESD204B Subclass 1 Timing |
|---|---|
Use Scenario: Eight-channel 16-bit ADC system sampling at 3.2 GSPS with synchronized capture across all channels. IC Role / Device Role / Timing Role: Primary clock fanout buffer distributing identical low-jitter 7.5 GHz clocks to all ADC sampling inputs while enabling polarity inversion for bottom-layer routing. Use Value: 45 fs RMS jitter maintains >72 dBFS SNR; ±25 ps skew ensures <0.1° inter-channel phase error at Nyquist. | Use Scenario: FPGA-based digital downconverter receiving JESD204B lanes from multiple ADCs requiring deterministic SYSREF alignment. IC Role / Device Role / Timing Role: Clock source for LTC6955-1's ÷2 output (OUT10), generating precise SYSREF pulses aligned to device clock edges. Use Value: Enables subclass 1 deterministic latency with <100 ps SYSREF-to-clock edge uncertainty across temperature. |
| Satellite Communication Modems | Millimeter-Wave Test Equipment |
Use Scenario: Multi-carrier DVB-S2X modulator using 12-bit DACs operating at 6.4 GSPS with I/Q channel matching. IC Role / Device Role / Timing Role: Single-point clock distribution to DAC clock inputs and FPGA interpolation logic with matched trace lengths. Use Value: 7.5 GHz bandwidth supports direct DAC clocking; 45 fs jitter prevents EVM degradation below –45 dB at 28 GHz carrier. | Use Scenario: Vector signal analyzer requiring ultra-stable local oscillator synthesis from 10 MHz reference up to 40 GHz. IC Role / Device Role / Timing Role: Low-noise buffer stage between ADF4371 synthesizer and mixer LO inputs, reducing integrated phase noise contribution. Use Value: 5 fs RMS additive jitter (12 kHz–20 MHz) adds <0.02° RMS phase error to 40 GHz LO, preserving measurement dynamic range. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar ultralow-jitter clock buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LMK04832RHAT | Integrated dual-loop PLL + 14-output JESD204B-compliant buffer; higher power (1.2 W), larger 40-pin WQFN; 50 fs RMS jitter at 2.5 GHz. | Requires external VCO for >3.2 GHz outputs; supports deterministic delay calibration; not rated for >105°C. | Select when system needs on-chip PLL re-synthesis and JESD204B subclass 1/2 support; avoid if only fanout is required or ambient >105°C. |
| ADCLK948BCPZ | 8-output CML buffer; 42 fs RMS jitter at 3.2 GHz; 32-pin LFCSP; no parallel control; fixed 8 outputs. | No output enable/disable or polarity inversion; limited to 3.2 GHz max output; lacks FILT-controlled noise filtering. | Select for space-constrained designs needing lowest possible jitter below 3.2 GHz; avoid when >8 outputs, >3.2 GHz, or programmable polarity is required. |
Compared with LMK04832RHAT, LTC6955IUKG#PBF offers lower jitter at 7.5 GHz and wider temperature rating but lacks PLL functionality. Compared with ADCLK948BCPZ, it provides more outputs, higher frequency capability, and flexible control-making it superior for scalable high-frequency fanout where PLL integration is unnecessary.
Availability
LTC6955IUKG#PBF is available at Aetrix Electronics and suitable for high-speed data acquisition, millimeter-wave test equipment, satellite communication modems, and JESD204B subclass 1 timing systems requiring stable component supply across extended temperature ranges.
Supply support for LTC6955IUKG#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, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving precision instrumentation, communications, and industrial markets since 1965.
The LTC6955IUKG#PBF belongs to Analog Devices' ultralow-jitter clock buffer family, designed specifically for high-resolution data converter clocking, wireless infrastructure, and test & measurement systems demanding sub-50 fs additive jitter and multi-GHz bandwidth.
FAQ
What is the maximum input frequency supported by the LTC6955IUKG#PBF?
The LTC6955IUKG#PBF supports differential input frequencies from DC to 7.5 GHz. This is confirmed in the Electrical Characteristics table (fIN = 7500 MHz, min/max unspecified but typ. 7.5 GHz). Operation at 7.5 GHz enables direct clocking of high-speed ADCs and DACs without frequency multiplication stages, preserving jitter performance.
Does the LTC6955IUKG#PBF support single-ended input drive?
Yes, the LTC6955IUKG#PBF supports single-ended input drive using AC-coupled configurations with external matching networks, as shown in Figure 3 of the datasheet. Its self-biased 250 Ω differential input impedance allows flexible interfacing to RF oscillators, LVPECL, or CML sources-even when driven single-ended-provided common-mode voltage remains within 1.6 V to 2.7 V.
How does the FILT pin affect jitter performance of the LTC6955IUKG#PBF?
The FILT pin enables an internal broadband noise filter in the input buffer. When set to V+, it improves phase noise floor by up to 8.8 dBc/Hz at 10 kHz offset for low-slew-rate inputs (<2 V/ns), reducing additive jitter. However, setting FILT = V+ for inputs with slew rate ≥2 V/ns degrades overall phase noise-so FILT must be selected based on measured input slew rate, not frequency alone.
Can the LTC6955IUKG#PBF drive 50 Ω single-ended loads directly?
No, the LTC6955IUKG#PBF outputs are optimized for 100 Ω differential termination. Driving a 50 Ω single-ended load directly violates the specified 100 Ω differential output resistance and causes signal reflection and amplitude loss. To interface to single-ended systems, use one side of the CML pair AC-coupled into 50 Ω, with the complementary side terminated to VCC or grounded per Figure 2 in the datasheet.
What is the purpose of the separate VOUT+ pins on the LTC6955IUKG#PBF?
The LTC6955IUKG#PBF has 11 dedicated VOUT+ pins (Pins 5, 8, 11, 14, 17, 20, 23, 26, 29, 32, 35) to isolate power delivery to each CML output driver. This separation minimizes supply-induced crosstalk between outputs, maintains consistent output swing across all 11 channels, and improves PSRR-critical for maintaining <45 fs RMS jitter when multiple outputs switch simultaneously.
LTC6955IUKG#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 52-WFQFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Last Time Buy
- Programmable:
- Not Verified
- Type:
- Fanout Buffer (Distribution)
- PLL:
- No
- Input:
- Differential
- Output:
- CML
- Number of Circuits:
- 1
- Ratio - Input:Output:
- 1:11
- Differential - Input:Output:
- Yes/Yes
- Frequency - Max:
- 7.5GHz
- Divider/Multiplier:
- Yes/No
- Voltage - Supply:
- 3.15V ~ 3.45V
- Operating Temperature:
- -40°C ~ 125°C
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
- Supplier Device Package:
- 52-QFN (7x8)
LTC6955IUKG#PBF FAQ
1.How can I place an order for LTC6955IUKG#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC6955IUKG#PBF on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for LTC6955IUKG#PBF reliable?
The price and inventory of LTC6955IUKG#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC6955IUKG#PBF is usually 5 days.
3.What payment methods are accepted for LTC6955IUKG#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC6955IUKG#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC6955IUKG#PBF?
LTC6955IUKG#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC6955IUKG#PBF order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for LTC6955IUKG#PBF?
For technical support, including LTC6955IUKG#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC6955IUKG#PBF requirements.
6.How does Aetrix verify that LTC6955IUKG#PBF is sourced from the original manufacturer or authorized distributors?
All LTC6955IUKG#PBF products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LTC6955IUKG#PBF meets industry standards.
7.What is the process for return or replacement of LTC6955IUKG#PBF?
All LTC6955IUKG#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC6955IUKG#PBF, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The LTC6955IUKG#PBF part is unused and in its original packaging.
Return procedure for LTC6955IUKG#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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