KAD2708L-21Q68 - 8-bit 210MSPS LVCMOS ADC, 68-QFN | Renesas
MPN： KAD2708L-21Q68 ✓ 啟用中KAD2708L-21Q68 概覽
A pipelined ADC is a high-speed sampling architecture that converts an analog input through a cascade of low-resolution flash stages, each stage producing a residue passed to the next. Pipelined ADCs sit within the broader ADC hierarchy as the dominant solution for sampling rates from ~10 MSPS to ~1 GSPS where successive-approximation (SAR) converters become too slow and flash converters become impractical due to comparator count. The KAD2708L family is one of the industry's lowest-power 8-bit high-performance ADC families, designed for communications, oscilloscope, and imaging front-ends.
Key features of the KAD2708L-21Q68 include 8-bit resolution, 210 MSPS maximum sampling rate, single-channel LVCMOS output, an over-range indicator for out-of-range detection, a selectable divide-by-2 input clock divider for flexible clocking, and pin compatibility across the broader KAD2708L/KAD2710C 68-QFN family offering 8- and 10-bit resolutions at 105 to 350 MSPS. The device operates from AVDD2 = 1.8 V and AVDD3 = 3.3 V supplies, providing easy interfacing to modern FPGA and ASIC LVCMOS receivers.
From an architecture standpoint, FemtoCharge™ technology uses a small switched-capacitor charge-redistribution front-end combined with a pipelined core to achieve wide input bandwidth and low aperture jitter. The LVCMOS output drivers ease board-level integration with FPGAs and ASICs that do not support LVDS, removing the need for external level-translation buffers. The 68-QFN package exposes the die pad for thermal dissipation, and the part consumes under 330 mW in operation.
Typical applications include digital oscilloscopes, communication test equipment, radar and lidar front-ends, IF signal digitisation in software-defined radio, medical imaging subsystems, and high-speed data-acquisition cards. The combination of low power, small footprint, and pin-compatible family scalability makes the KAD2708L-21Q68 a strong fit where multiple sampling rates or resolutions are needed across product variants.
When designing with this part, ensure the analog input network is designed for the ADC's full-power input bandwidth and that the LVCMOS outputs are properly terminated at the receiver. The selectable divide-by-2 input clock divider allows use of an external clock oscillator up to 420 MHz while presenting a clean 210 MHz internal sampling clock. Decoupling must follow the datasheet reference layout, particularly the exposed pad connection to the analog ground plane.
This page synthesizes distributor pricing, drop-in same-package alternatives, comparison parameters, and practical design notes not aggregated on the manufacturer datasheet, providing a single reference for sourcing, selection, and PCB-level integration decisions.
直接替換替代品，適用於 KAD2708L-21Q68 — 相同封裝，腳位對腳位相容。需重新設計 PCB 的不同封裝零件不列入。
此系列的變體
與下列產品可直接替換的同系列型號： KAD2708L-21Q68 （相同外形與佔位） — 差異在於 Architecture, Package, Operating Temperature Range, Number of Channels, Resolution.
KAD2708L-17Q68
✅ 直接替換聯絡詢價
查看資料表 →KAD2708L-27Q68
✅ 直接替換聯絡詢價
查看資料表 →KAD2708L-35Q68
✅ 直接替換聯絡詢價
查看資料表 →KAD2710C-21Q68
✅ 直接替換聯絡詢價
查看資料表 →KAD2710C-17Q68
✅ 直接替換聯絡詢價
查看資料表 →KAD2708L-21Q68 最大額定值與電氣特性
| 解析度 | 8 bit |
| 取樣率 | 210 MSPS |
| Number of Channels | 1 |
| Architecture | Pipelined (FemtoCharge™ technology) |
| Digital Output Type | LVCMOS |
| Input Clock Divider | Selectable divide-by-2 |
| Analog Supply Voltage (AVDD2) | 1.8 V |
| Digital Supply Voltage (AVDD3) | 3.3 V |
| SNR at fIN = 175 MHz | 48.8 dBFS |
| Over-Range Indicator | Yes |
| 封裝 | 68-QFN (10x10 mm) |
| 安裝類型 | Surface Mount |
| RoHS 狀態 | Compliant |
| Family Pin-Compatibility | Pin-compatible with KAD2708L (8-bit) and KAD2710C (10-bit) at 105-350 MSPS |
| Process Technology | Standard CMOS with FemtoCharge™ |
KAD2708L-21Q68 68-qfn (10x10 mm) 腳位配置指南
KAD2708L-21Q68（68-qfn (10x10 mm) 封裝）的腳位配置。 此類比元件具有輸入、輸出與電源腳位。偏移歸零、補償與致能腳位配置請參閱製造商資料表。適用於訊號調理與放大器電路。
無詳細腳位定義資料： KAD2708L-21Q68.
請參閱 資料表 以查看完整腳位配置。
典型應用
KAD2708L-21Q68 適用於 6 應用s: Digital Oscilloscope Front-End, Communications Test Equipment IF Sampling, Radar and Lidar Signal Acquisition, Software-Defined Radio Receiver, Medical Imaging Subsystems, High-Speed Data Acquisition Card.
Digital Oscilloscope Front-End
The KAD2708L-21Q68's 210 MSPS sampling rate and 48.8 dBFS SNR at 175 MHz input bandwidth make it well-suited for digitising repetitive and single-shot signals in mid-range digital oscilloscopes. Placed after the front-end attenuator and programmable-gain amplifier, the ADC captures waveforms with sufficient bandwidth for 100-200 MHz class instruments. The LVCMOS outputs connect directly to the FPGA acquisition memory without level translation. Compared with the LVDS variants, the LVCMOS output simplifies PCB routing but limits trace length to a few centimetres to avoid digital switching noise coupling back into the analog input.
推薦
Communications Test Equipment IF Sampling
The KAD2708L-21Q68 supports undersampling of intermediate-frequency (IF) signals in cable, wireless, and satellite test equipment, thanks to its wide input bandwidth and 48.8 dBFS SNR at 175 MHz. Placed after a bandpass filter and gain stage, the ADC digitises IF signals up to several hundred MHz, allowing digital demodulation in an FPGA or DSP. The selectable divide-by-2 input clock divider simplifies clocking with a 420 MHz crystal oscillator, while the 1.8 V analog and 3.3 V digital supplies align with modern low-power FPGA bank voltages.
推薦
Radar and Lidar Signal Acquisition
Automotive and industrial radar/lidar front-ends rely on fast ADCs to digitise wideband chirp or pulse returns. The KAD2708L-21Q68's 210 MSPS sample rate provides enough bandwidth for short-range FMCW chirp demodulation up to ~100 MHz instantaneous bandwidth, and the FemtoCharge™ pipeline delivers low aperture jitter for accurate phase measurement. Its 68-QFN package dissipates under 330 mW, helping meet thermal budgets in sealed outdoor enclosures. Pin compatibility with the KAD2710C 10-bit family allows tier upgrades without PCB changes.
推薦
Software-Defined Radio Receiver
The KAD2708L-21Q68 fits the ADC stage of a software-defined radio receiver where 8-bit dynamic range is acceptable and low power is critical. Placed at the IF or direct-conversion baseband output, the ADC samples I/Q signals into an FPGA for channelisation, demodulation, and protocol decoding. The 1.8 V/3.3 V supplies ease integration with battery-powered portable SDR platforms, and the 68-QFN footprint keeps the BOM compact. For higher dynamic range, the pin-compatible KAD2710C-21Q68 (10-bit) can be substituted.
推薦
Medical Imaging Subsystems
Ultrasound and optical-imaging subsystems use the KAD2708L-21Q68 to digitise transducer or photodiode arrays at rates up to 210 MSPS. The 48.8 dBFS SNR supports the dynamic-range needs of mid-tier ultrasound beamformers, while the LVCMOS outputs simplify fan-out to multiple FPGA banks. The FemtoCharge™ pipeline maintains low latency, important for time-of-flight and beam-steering calculations. Operating from 1.8 V analog and 3.3 V digital supplies helps meet patient-safety leakage budgets in medical devices.
推薦
High-Speed Data Acquisition Card
PCIe and PXIe data-acquisition cards use the KAD2708L-21Q68 to deliver 8-bit, 210 MSPS single-channel capture for general-purpose digitiser modules. The exposed-pad 68-QFN package simplifies thermal management in card-edge form factors, and the LVCMOS outputs allow direct connection to onboard FPGAs without external buffers. The selectable divide-by-2 clock divider relaxes front-panel clock-distribution design, while the over-range indicator provides the FPGA with a fast flag for gain-ranging control loops.
推薦
推薦產品摘要
工程參考資料，適用於 KAD2708L-21Q68 — 比較、設計指引及合規資訊。
選型指南
與替代品比較
| 參數 | 本產品 | KAD2708L-17Q68 | KAD2708L-27Q68 | KAD2708L-35Q68 | KAD2710C-21Q68 | KAD2710C-17Q68 |
|---|---|---|---|---|---|---|
| Brand | Renesas Electronics | Renesas Electronics | Renesas Electronics | Renesas Electronics | Renesas Electronics | Renesas Electronics |
| 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 |
| Resolution | 8 bit | 8 bit | 8 bit | 8 bit | 10 bit | 10 bit |
| Sampling Rate | 210 MSPS | 170 MSPS | 275 MSPS | 350 MSPS | 210 MSPS | 170 MSPS |
| Digital Output Type | LVCMOS | LVCMOS | LVCMOS | LVCMOS | LVCMOS | LVCMOS |
| Channels | 1 | 1 | 1 | 1 | 1 | 1 |
| Architecture | Pipelined FemtoCharge™ | Pipelined FemtoCharge™ | Pipelined FemtoCharge™ | Pipelined FemtoCharge™ | Pipelined FemtoCharge™ | Pipelined FemtoCharge™ |
| Pin-Compatible Family Member | Yes (8-bit, 210 MSPS) | Yes (8-bit, 170 MSPS) | Yes (8-bit, 275 MSPS) | Yes (8-bit, 350 MSPS) | Yes (10-bit, 210 MSPS) | Yes (10-bit, 170 MSPS) |
主要差異化特點
- Pin-compatible scalability across 105-350 MSPS and 8/10-bit resolutions (對比KAD2710C-21Q68 (10-bit, 210 MSPS))
- Lowest-power 8-bit 210 MSPS ADC in the family (對比KAD2708L-27Q68 (275 MSPS))
- FemtoCharge™ technology on standard CMOS process (對比Competitor SiGe or BiCMOS ADCs at 210 MSPS)
設計說明
The KAD2708L-21Q68 requires two supply rails: AVDD2 = 1.8 V for the analog core and AVDD3 = 3.3 V for the LVCMOS output drivers. Use a low-noise LDO (e.g., ADP7104 or TPS7A4701) for AVDD2 to achieve the rated 48.8 dBFS SNR. Place a ferrite bead or small resistor between AVDD2 and AVDD3 grounds if they are tied at a single point, and add 10 uF + 0.1 uF ceramic decoupling at each supply pin per the KAD2708L datasheet reference layout.
Route the analog input as a 50-ohm controlled-impedance trace with no stubs, and place the ADC within 5 cm of the front-end amplifier. The 68-QFN exposed pad must be soldered to a continuous analog ground plane for thermal dissipation and electrical performance. Keep LVCMOS output traces short (less than 5 cm) to minimise digital switching noise coupling; if longer runs are needed, add source-series termination resistors at the ADC output pins.
Do not assume that LVCMOS and LVDS output variants of the KAD2708L family share the same pinout; verify the datasheet pin map for the KAD2708L-21Q68 specifically. The selectable divide-by-2 input clock divider must be configured via the appropriate logic level at power-up, otherwise the ADC may operate at twice the expected sample rate and fail downstream timing. The over-range indicator pin should be monitored by the FPGA for automatic gain control.
FemtoCharge™ pipeline ADCs have low aperture jitter but the LVCMOS outputs can inject switching noise back into the analog input. Estimated: at 210 MSPS with 8 LVCMOS outputs switching simultaneously, ground-bounce noise can reach tens of millivolts unless the digital return current is isolated from the analog ground with a split-plane technique. Use a single-point ground tie near the ADC exposed pad, with separate analog and digital ground regions extending outward.
合規資訊
RoHS and lead-free compliance confirmed via Renesas/Intersil product page. Halogen-free status not stated in verified data. AEC-Q100 automotive qualification is not applicable to the KAD2708L family.
