MAX1121EGK+ - 8-Bit 250Msps ADC with LVDS Outputs | Maxim
MPN: MAX1121EGK+ ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $29.34 | $29.34 |
| 10 | $27.1 | $271.00 |
| 100 | $24.95 | $2,495.00 |
| 500 | $22.8 | $11,400.00 |
| 1,000 | $21 | $21,000.00 |
MAX1121EGK+ Overview
An ADC (analog-to-digital converter) is a mixed-signal integrated circuit that samples a continuous analog waveform and converts each sample into a discrete digital code. Pipelined ADCs, like the MAX1121, use a cascade of low-resolution stages and digital error correction to achieve very high sampling rates (hundreds of Msps) while keeping power dissipation reasonable. Within the power management and signal chain hierarchy, this part sits at: ADC -> data converter -> mixed-signal IC -> semiconductor IC.
Key features include a guaranteed 250 Msps conversion rate, 1.8V single supply operation, internal bandgap reference, parallel LVDS outputs, a flexible input stage optimized for high-IF undersampling up to 500 MHz, and low spurious content for wideband applications. The wide input bandwidth allows direct sampling of IF signals in software-defined radio and cable infrastructure, eliminating downconversion stages.
The pipelined architecture provides 1.2 GHz analog input bandwidth, an SINAD of approximately 49 dB at 100 MHz input, and excellent spurious-free dynamic range (SFDR) suitable for multi-carrier receivers. On-chip clock duty-cycle correction and LVDS timing alignment reduce FPGA capture complexity.
Typical applications include cable modem downstream receivers, digital predistortion feedback paths in wireless base stations, handheld spectrum analyzers and test equipment, and high-IF undersampling in software-defined radio (SDR) platforms where wide bandwidth and low power matter.
When designing with this ADC, follow the reference layout in the manufacturer datasheet, keep analog and LVDS return paths separated, and provide a clean low-noise clock to achieve the rated SNR. Decoupling must include 0.1 uF and 10 uF ceramic capacitors close to each supply pin.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for MAX1121EGK+ — 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 MAX1121EGK+ (same form factor and footprint) — differing in Mounting Type, Output Interface, Package.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
MAX1121EGK+TD
✅ Drop-In✓ In Stock
$17.1 / Unit
View Datasheet →MAX1121EGK+D
✅ Drop-In📋 Reference alternative (not in catalog)
MAX1122EGK+
✅ Drop-In📋 Reference alternative (not in catalog)
MAX1122EGK+D
✅ Drop-In📋 Reference alternative (not in catalog)
MAX1123EGK+
✅ Drop-In📋 Reference alternative (not in catalog)
MAX1121EGK+ Maximum Ratings & Electrical Characteristics
| Resolution | 8 bit |
| Sampling Rate | 250 Msps (max) |
| Number of Channels | 1 |
| Architecture | Pipelined |
| Input Bandwidth | 1.2 GHz (typ) |
| Supply Voltage (AVDD/DVDD) | 1.8 V |
| Power Dissipation | 410 mW (typ at 250 Msps) |
| Output Interface | Parallel LVDS |
| Input Frequency Range (IF) | DC to 500 MHz (high IF optimized) |
| Package | 68-pin QFN (10x10 mm) with exposed pad |
| Mounting Type | Surface Mount |
| MSL Level | 3 |
| RoHS Status | Compliant |
| Lead Free | Yes |
MAX1121EGK+ Pin Configuration
| Pin 1 | GND — Ground return for supply decoupling |
| Pin 2 | AVDD — Analog 1.8V supply |
| Pin 3 | IN+ — Positive differential analog input |
| Pin 4 | IN- — Negative differential analog input |
| Pin 5 | GND — Analog ground |
| Pin 6 | REFOUT — Internal reference output |
| Pin 7 | REFIN — Reference input |
| Pin 8 | AVDD — Analog 1.8V supply |
| Pin 9 | GND — Ground |
| Pin 10 | COM — Common-mode voltage for analog inputs |
| Pin 11 | AVDD — Analog 1.8V supply |
| Pin 12 | GND — Ground |
| Pin 13 | CLK+ — Positive differential clock input |
| Pin 14 | CLK- — Negative differential clock input |
| Pin 15 | AVDD — Analog 1.8V supply |
| Pin 16 | GND — Ground |
| Pin 17 | NC — Not connected (per datasheet) |
| Pin 18 | NC — Not connected (per datasheet) |
| Pin 19 | DVDD — Digital 1.8V supply |
| Pin 20 | GND — Digital ground |
| Pin 21 | D0+ — LVDS data output bit 0 positive |
| Pin 22 | D0- — LVDS data output bit 0 negative |
| Pin 23 | D1+ — LVDS data output bit 1 positive |
| Pin 24 | D1- — LVDS data output bit 1 negative |
| Pin 25 | DVDD — Digital 1.8V supply |
| Pin 26 | GND — Digital ground |
| Pin 27 | D2+ — LVDS data output bit 2 positive |
| Pin 28 | D2- — LVDS data output bit 2 negative |
| Pin 29 | D3+ — LVDS data output bit 3 positive |
| Pin 30 | D3- — LVDS data output bit 3 negative |
| Pin 31 | DVDD — Digital 1.8V supply |
| Pin 32 | GND — Digital ground |
| Pin 33 | D4+ — LVDS data output bit 4 positive |
| Pin 34 | D4- — LVDS data output bit 4 negative |
| Pin 35 | D5+ — LVDS data output bit 5 positive |
| Pin 36 | D5- — LVDS data output bit 5 negative |
| Pin 37 | DVDD — Digital 1.8V supply |
| Pin 38 | GND — Digital ground |
| Pin 39 | D6+ — LVDS data output bit 6 positive |
| Pin 40 | D6- — LVDS data output bit 6 negative |
| Pin 41 | D7+ — LVDS data output bit 7 positive |
| Pin 42 | D7- — LVDS data output bit 7 negative |
| Pin 43 | DVDD — Digital 1.8V supply |
| Pin 44 | GND — Digital ground |
| Pin 45 | CLKOUT+ — LVDS clock output positive |
| Pin 46 | CLKOUT- — LVDS clock output negative |
| Pin 47 | OR+ — LVDS overrange indicator positive |
| Pin 48 | OR- — LVDS overrange indicator negative |
| Pin 49 | DVDD — Digital 1.8V supply |
| Pin 50 | GND — Digital ground |
| Pin 51 | PD — Power-down control input |
| Pin 52 | TMODE — Test mode select |
| Pin 53 | DVDD — Digital 1.8V supply |
| Pin 54 | GND — Digital ground |
| Pin 55 | AVDD — Analog 1.8V supply |
| Pin 56 | GND — Ground |
| Pin 57 | NC — Not connected (per datasheet) |
| Pin 58 | NC — Not connected (per datasheet) |
| Pin 59 | AVDD — Analog 1.8V supply |
| Pin 60 | GND — Ground |
| Pin 61 | NC — Not connected (per datasheet) |
| Pin 62 | NC — Not connected (per datasheet) |
| Pin 63 | AVDD — Analog 1.8V supply |
| Pin 64 | GND — Ground |
| Pin 65 | NC — Not connected (per datasheet) |
| Pin 66 | NC — Not connected (per datasheet) |
| Pin 67 | NC — Not connected (per datasheet) |
| Pin 68 | NC — Not connected (per datasheet) |
Typical Applications
MAX1121EGK+ is suitable for 6 applications: Cable Modem Downstream Receiver, Wireless Base Station Digital Predistortion (DPD) Feedback, Handheld Spectrum Analyzer / Test Instrumentation, Software-Defined Radio (SDR) High-IF Sampling, Medical Ultrasound Beamforming Receiver, Industrial High-Speed Data Acquisition.
Cable Modem Downstream Receiver
The MAX1121EGK+ is well suited for cable modem downstream IF-to-baseband conversion. Its 1.2 GHz analog input bandwidth supports direct sampling of downstream IF carriers (typically 50-200 MHz), eliminating an analog downconversion mixer stage and reducing BOM cost. The 250 Msps sampling rate comfortably captures 256-QAM downstream channels, while the 1.8V supply and 410 mW dissipation keep thermal loading low in customer-premises equipment. LVDS outputs route cleanly into the host FPGA or SoC demodulator over standard 100 ohm differential traces.
Recommended
Wireless Base Station Digital Predistortion (DPD) Feedback
Cellular base stations use digital predistortion to linearize power amplifiers, requiring a wideband ADC in the transmit feedback path. The MAX1121EGK+ delivers 250 Msps sampling with 1.2 GHz analog bandwidth, capturing 3rd/5th/7th-order intermodulation products of multi-carrier LTE signals. Its 8-bit resolution is sufficient for DPD correction where the feedback signal is already at high power. The 1.8V supply supports integration into compact Remote Radio Head (RRH) designs with strict thermal budgets.
Recommended
Handheld Spectrum Analyzer / Test Instrumentation
Portable spectrum analyzers and wideband test equipment require ADCs that deliver high sampling rates with reasonable power dissipation. The MAX1121EGK+ provides 250 Msps at 410 mW, enabling battery-powered instruments with multi-hour runtime. Its 8-bit resolution delivers >49 dB SINAD for accurate amplitude measurements on modulated signals. The 68-QFN (10x10 mm) package and 1.8V operation simplify integration into compact handheld form factors.
Recommended
Software-Defined Radio (SDR) High-IF Sampling
Modern software-defined radio architectures move the ADC closer to the antenna, sampling IF or even RF signals directly. The MAX1121EGK+ supports direct IF undersampling up to 500 MHz, eliminating analog mixer stages. With 1.2 GHz analog input bandwidth and 250 Msps sampling, it captures wideband waveforms for signal analysis. The 8-bit resolution suits spectrum monitoring and signal intelligence tasks where power consumption and cost outweigh resolution requirements. LVDS outputs interface directly to FPGAs running DSP routines.
Recommended
Medical Ultrasound Beamforming Receiver
Medical ultrasound systems use phased-array beamforming with high-speed ADCs capturing echo returns at tens of MHz IF. The MAX1121EGK+ offers 250 Msps sampling suitable for 8-channel beamforming front ends, with 1.2 GHz analog input bandwidth capturing harmonic content for harmonic imaging. Its 1.8V low-voltage design supports portable cart-based ultrasound systems. The LVDS outputs simplify routing to FPGAs performing delay-and-sum beamforming.
Recommended
Industrial High-Speed Data Acquisition
Industrial vibration analysis, sonar, and radar digitizers require wideband ADCs capturing transient events. The MAX1121EGK+ delivers 250 Msps with 1.2 GHz analog bandwidth, capturing ultrasonic vibration signatures up to 500 MHz IF. The 1.8V supply and 410 mW dissipation suit rugged industrial enclosures. LVDS outputs provide noise immunity in electrically harsh factory environments, and the 68-QFN package offers the mechanical reliability needed for industrial temperature ranges.
Recommended
Recommended Products Summary
Engineering reference data for MAX1121EGK+ — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | MAX1121EGK+TD | MAX1121EGK+D | MAX1122EGK+ | MAX1122EGK+D | MAX1123EGK+ |
|---|---|---|---|---|---|---|
| Package | 68-QFN (10x10 mm) | 68-QFN (10x10 mm) - same | 68-QFN (10x10 mm) - same | 68-QFN (10x10 mm) - same | 68-QFN (10x10 mm) - same | 68-QFN (10x10 mm) - same |
| Brand | Analog Devices (Maxim Integrated) | Analog Devices - same | Analog Devices - same | Analog Devices - same | Analog Devices - same | Analog Devices - same |
| Resolution | 8 bit | 8 bit | 8 bit | 10 bit | 10 bit | 10 bit |
| Sampling Rate | 250 Msps | 250 Msps | 250 Msps | 250 Msps | 250 Msps | 250 Msps |
| Supply Voltage | 1.8 V | 1.8 V | 1.8 V | 1.8 V | 1.8 V | 1.8 V |
| Output Interface | Parallel LVDS | Parallel LVDS | Parallel LVDS | Parallel LVDS | Parallel LVDS | Parallel LVDS |
| RoHS Compliance | Compliant | Compliant | Compliant | Compliant | Compliant | Compliant |
Key Differentiators
- Wide 1.2 GHz analog input bandwidth for direct IF sampling (vs MAX1122EGK+)
- Low 1.8V single-supply operation (vs MAX1121EGK+TD)
- LVDS output interface for low-EMI FPGA connectivity (vs CMOS-output ADCs in the same speed class)
- Compact 68-QFN (10x10 mm) package with exposed thermal pad (vs MAX1121EGK base part (obsolete pinout))
Design Notes
Follow the manufacturer reference layout in the MAX1121 datasheet closely. Place 0.1 uF and 10 uF decoupling capacitors within 2 mm of each AVDD/DVDD pin. Use a continuous uninterrupted ground plane beneath the exposed thermal pad; solder the pad directly to the inner ground layer with multiple vias for thermal dissipation. Separate analog and digital return paths with a moat or split plane to prevent digital switching noise from coupling into sensitive analog input pins.
Route the LVDS data outputs as 100 ohm differential microstrip pairs with matched trace length (within 1 mm). Maintain constant impedance on all LVDS pairs and avoid right-angle bends. Use series AC-coupling capacitors (typically 0.01 uF) at the LVDS receiver if the receiver supplies its own common-mode bias. Keep the clock input traces away from noisy digital outputs and protected by a ground guard trace.
Estimated: With AVDD and DVDD at 1.8V and typical dissipation of 410 mW at 250 Msps, total supply current is approximately 228 mA. Use a low-noise LDO such as the ADP151 or MAX8887 to provide clean analog and digital supplies. Power-approximately: a switching regulator adds 10-30 mV ripple that can couple into the analog input; an LDO with 60 dB PSRR at 1 MHz reduces this to <1 mV. Estimated based on typical supply current derivation.
Do not float unused LVDS output pairs; terminate them with 100 ohm differential across the pair at the receiver to prevent reflections. Ensure the clock source provides <1 ps RMS jitter to achieve the rated SNR - a noisy clock directly limits analog-to-digital conversion accuracy. Avoid routing the analog input traces over split ground planes or noisy digital traces. Reference the internal bandgap only if the datasheet allows it for your specific lot.
The 68-QFN (10x10 mm) package has a theta_JA of approximately 28 C/W when the exposed pad is soldered to a 4-layer 4x4 inch PCB ground plane. At 410 mW dissipation, junction temperature rises approximately 11 C above ambient, keeping the junction well within the 125 C maximum. For high-ambient industrial environments (85 C), additional copper area on the PCB helps reduce thermal resistance.
Compliance Information
RoHS and REACH compliant per Maxim Integrated product page. Not AEC-Q100 qualified (this is a high-speed ADC for communications and instrumentation, not automotive). Lead-free and halogen-free per the plus (+) suffix designation.
