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Analog Devices Inc. AD6644AST-40
- Part No.:
- AD6644AST-40
- Manufacturer:
- Analog Devices Inc.
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 52-LQFP
- Datasheet:
-
AD6644AST-40.pdf
- Description:
- IC ADC 14BIT 40MSPS 52-LQFP
- Quantity:
- Payment:
- Shipping:
Inventory:37,757
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Product details
Overview
AD6644AST-40 from Analog Devices is a 14-bit, 40 MSPS monolithic analog-to-digital converter (ADC) with differential analog inputs, 100 dB two-tone SFDR, 74 dB SNR at 2.2 MHz, and 250 MHz analog input bandwidth. It integrates on-chip track-and-hold and 2.4 V reference, and targets IF sampling in multichannel digital receivers.
For engineers reviewing the AD6644AST-40 datasheet, AD6644AST-40 pinout, AD6644AST-40 application, or AD6644AST-40 equivalent, this page delivers verified specifications, validated pin functions, confirmed LQFP-52 package mapping, real-world communication receiver use cases, and two technically documented alternative ADCs for multimode baseband and IF digitization.
Technical Context
The AD6644AST-40 employs a three-stage subrange architecture with pipelined track-and-hold stages (TH1–TH5), 5-bit coarse ADC1 + DAC1 (laser-trimmed), 5-bit ADC2 + DAC2, and final 6-bit ADC3 - all coordinated by digital error correction logic to deliver 14-bit twos complement output. Its differential ENCODE/ENCODE interface requires <300 fs sampling jitter for rated performance.
It operates with AVCC = 5 V (analog supply) and DVCC = 3.3 V (digital supply), supports 15–40 MSPS conversion rates, and features CMOS-compatible outputs with DRY (data-ready) and OVR (overrange) status signals. The analog input stage accepts ±0.55 V differential swing around 2.4 V common-mode, yielding 2.2 V p-p full-scale range.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 14-bit - guarantees monotonicity and no missing codes across full temperature range. |
| Sample Rate | 40 MSPS - maximum guaranteed conversion rate for parametric compliance at −25°C to +85°C. |
| Two-Tone SFDR | 100 dBFS - spurious-free dynamic range measured with 15 MHz / 15.5 MHz tones at −7 dBFS, enabling clean wideband signal capture. |
| Analog Input Bandwidth | 250 MHz - usable frequency range before −3 dB roll-off, supporting direct IF sampling up to cellular/WCDMA bands. |
| Power Dissipation | 1.3 W - total consumption (IAVCC = 276 mA @ 5 V, IDVCC = 36 mA @ 3.3 V), optimized for high-speed mixed-signal systems. |
| Aperture Jitter | 0.2 ps rms - enables >74 dB SNR at 30.5 MHz input without external clock conditioning. |
| Digital Output Format | Twos complement - simplifies FPGA/ASIC interface with standard signed integer arithmetic and no post-processing. |
Pinout & Package
AD6644AST-40 is housed in a 52-lead plastic low-profile quad flat package (LQFP), RoHS-compliant, rated for −25°C to +85°C ambient operation. Thermal resistance θJA = 33°C/W on a 6-layer PCB with solid ground plane.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| AIN / AIN | Differential analog input pair | Accepts ±0.55 V swing around 2.4 V common-mode; 1 kΩ differential resistance, 1.5 pF capacitance - requires matched layout and transformer/capacitive AC coupling. |
| ENCODE / ENCODE | Differential encode clock inputs | Trigger conversion on rising edge; require <300 fs jitter and 50% duty cycle for rated SFDR; internally biased, no external termination needed. |
| D0–D13 | Parallel digital output bus | 14-bit twos complement CMOS outputs (3.3 V compatible); D0 = LSB, D13 = MSB; timing-critical - must meet tE_FL ≤ 9.2 ns hold/setup windows. |
| DRY | Data-ready strobe | Inverted, delayed version of ENCODE; indicates valid data window - used for latching D0–D13 in synchronous logic. |
| OVR | Overrange flag | Active-high signal indicating analog input exceeded ±FS range; enables real-time clipping detection in receiver AGC loops. |
| VREF | 2.4 V analog reference output | Stable internal voltage source; must be bypassed with 0.1 µF microwave capacitor to GND for noise suppression. |
| DMID | Digital output midpoint reference | ≈DVCC/2 (1.65 V); provides common-mode level for interfacing to 3.3 V CMOS receivers. |
| AVCC / DVCC / GND | Power and ground terminals | Separate 5 V analog (AVCC) and 3.3 V digital (DVCC) supplies; 24 dedicated GND pins minimize ground bounce and improve PSRR. |
Key Features
| Feature | Design Value |
|---|---|
| On-chip track-and-hold + reference | Eliminates need for external TH circuitry or precision voltage reference ICs - reduces BOM count and layout sensitivity. |
| Pin compatibility with AD6645 | Enables drop-in upgrade path to higher-speed 13-bit variant (65 MSPS) without PCB redesign or firmware changes. |
| Differential analog and encode interfaces | Rejects common-mode noise and EMI in RF front-ends; supports transformer-coupled IF inputs typical in GSM/CDMA base stations. |
| 100 dB two-tone SFDR | Supports simultaneous reception of multiple closely spaced carriers in software-defined radios without analog pre-filtering. |
| 3.3 V CMOS digital outputs | Direct interface to Xilinx Virtex FPGAs or ASICs without level-shifting - simplifies timing closure and reduces power. |
Applications
| AMPS/IS-136 Base Station Receiver | WCDMA Node B IF Digitizer |
|---|---|
Use Scenario: Digitizing 45 MHz IF signals from multi-carrier AMPS/IS-136 channelizers prior to digital downconversion and demodulation. IC Role / Device Role / Timing Role: High-linearity IF sampling ADC providing 14-bit resolution and 100 dB SFDR to preserve adjacent-channel interference margin. Use Value: Enables single-chip digitization of up to 4 simultaneous voice channels within 1.25 MHz bandwidth, reducing analog filter complexity and calibration overhead. |
Use Scenario: Capturing 190 MHz WCDMA IF output from quadrature mixer in macrocell Node B transceiver. IC Role / Device Role / Timing Role: Wideband ADC with 250 MHz analog bandwidth and low aperture jitter, synchronizing to 40 MSPS system clock for 5 MHz channel processing. Use Value: Maintains EVM < 8% under 64-QAM modulation by preserving SNR > 73 dB across 30.5 MHz input tone - critical for 3GPP R99 compliance. |
| Radar Pulse-Doppler Processor | Communications Test Instrumentation |
Use Scenario: Sampling intermediate frequency outputs from pulsed radar receivers operating at L-band (1–2 GHz) with 10–50 MHz IF bandwidth. IC Role / Device Role / Timing Role: High-SFDR ADC capturing short-duration pulses with minimal harmonic distortion to support accurate Doppler shift estimation. Use Value: 92 dBc worst-harmonic at 2.2 MHz and 85 dBc at 30.5 MHz ensures unambiguous target velocity resolution in clutter-limited environments. |
Use Scenario: Embedded digitizer in vector signal analyzer measuring spectral purity of LTE eNodeB transmitters. IC Role / Device Role / Timing Role: Reference-grade ADC validating transmitter ACLR and EVM by capturing 20 MHz LTE signals at baseband or IF. Use Value: 74.5 dB SNR and 100 dB two-tone SFDR provide measurement floor 15 dB below 3GPP conformance limits - eliminating need for external averaging. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-speed ADC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AD6644AST-65 | Same die, guaranteed 65 MSPS sample rate; identical pinout, timing, and analog specs except max conversion rate and associated AC performance at higher frequencies. | Required for systems needing >40 MSPS IF sampling (e.g., wideband CDMA2000 1xEV-DO). | Select AD6644AST-65 when Nyquist zone coverage beyond 20 MHz is mandatory; AD6644AST-40 suffices for 15 MHz WCDMA or dual-IF architectures. |
| AD9240AST-40 | 14-bit, 40 MSPS ADC with 72 dB SNR (typ), 88 dB SFDR, and 105 MHz analog bandwidth; uses different architecture (folded-cascade), no integrated reference. | Suitable for cost-sensitive industrial imaging or lower-dynamic-range instrumentation where 100 dB SFDR is not required. | Choose AD9240AST-40 only if system SFDR budget allows ≥12 dB degradation; AD6644AST-40 remains preferred for telecom infrastructure due to superior linearity and integrated reference. |
Compared with AD6644AST-65, the AD6644AST-40 trades maximum sample rate for tighter thermal/power constraints while retaining identical pinout and interface logic; versus AD9240AST-40, it delivers 12 dB higher SFDR and 145 MHz wider analog bandwidth at the cost of higher power and process-specific design maturity.
Availability
AD6644AST-40 is available at Aetrix Electronics and suitable for multichannel base station receivers, WCDMA Node B IF digitizers, and radar pulse-Doppler processors requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for AD6644AST-40 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, headquartered in Norwood, MA, with design centers worldwide and ISO 9001-certified manufacturing.
The AD6644 belongs to Analog Devices' SoftCell® transceiver chipset family, engineered specifically for software-defined radio infrastructure - emphasizing wideband linearity, low jitter, and seamless integration with digital downconverters like the AD6620.
FAQ
What is the guaranteed maximum sample rate for AD6644AST-40?
The AD6644AST-40 is guaranteed to operate at 40 MSPS across its full temperature range (−25°C to +85°C). This is explicitly specified in Table 3 of the Rev. D datasheet under "Maximum Conversion Rate" for the AD6644AST-40 column. Performance at higher rates (e.g., 65 MSPS) applies only to the AD6644AST-65 variant.
Does AD6644AST-40 include an internal voltage reference?
Yes, the AD6644AST-40 integrates a precise 2.4 V internal reference (VREF pin), confirmed in the General Description and Pin Function Descriptions sections. It requires external 0.1 µF microwave capacitor bypassing to GND per Figure 3 and Table 8 - no external reference IC is needed for basic operation.
Is AD6644AST-40 pin-compatible with other members of the AD6644 family?
Yes, AD6644AST-40 is pin-compatible with AD6644AST-65 and functionally compatible with AD6645 per the Features section. All share identical 52-lead LQFP packaging, pin numbering, and I/O assignment - enabling hardware reuse across 40 MSPS and 65 MSPS configurations without layout changes.
What digital output format does AD6644AST-40 use?
The AD6644AST-40 outputs data in twos complement format, as stated in both the Features list and Digital Specifications table. D0 is the LSB and D13 is the MSB, with DMID providing a 1.65 V midpoint reference for interfacing to 3.3 V CMOS logic.
What is the analog input voltage range for AD6644AST-40?
The AD6644AST-40 accepts a differential analog input voltage span of 2.2 V p-p, with each input (AIN/AIN) centered at 2.4 V and swinging ±0.55 V. This is specified in Table 1 under "Differential Input Voltage Span" and confirmed in the Theory of Operation section.
AD6644AST-40 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 52-LQFP
- Packaging:
- Bag
- Product Status:
- Obsolete
- Number of Bits:
- 14
- Sampling Rate (Per Second):
- 40M
- Number of Inputs:
- -
- Input Type:
- -
- Data Interface:
- Parallel
- Configuration:
- -
- Ratio - S/H:ADC:
- -
- Number of A/D Converters:
- 4
- Architecture:
- -
- Reference Type:
- -
- Voltage - Supply, Analog:
- -
- Voltage - Supply, Digital:
- -
- Features:
- -
- Operating Temperature:
- -25°C ~ 85°C
- Supplier Device Package:
- 52-LQFP (10x10)
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
AD6644AST-40 FAQ
1.How can I place an order for AD6644AST-40 through Aetrix?
Please submit a Request for Quotation (RFQ) for AD6644AST-40 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 AD6644AST-40 reliable?
The price and inventory of AD6644AST-40 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AD6644AST-40 is usually 5 days.
3.What payment methods are accepted for AD6644AST-40?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AD6644AST-40 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AD6644AST-40?
AD6644AST-40 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AD6644AST-40 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 AD6644AST-40?
For technical support, including AD6644AST-40 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AD6644AST-40 requirements.
6.How does Aetrix verify that AD6644AST-40 is sourced from the original manufacturer or authorized distributors?
All AD6644AST-40 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 AD6644AST-40 meets industry standards.
7.What is the process for return or replacement of AD6644AST-40?
All AD6644AST-40 units undergo pre-shipment inspection (PSI). If there is an issue with AD6644AST-40, 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 AD6644AST-40 part is unused and in its original packaging.
Return procedure for AD6644AST-40:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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