基于MAX19994A設計的雙路RF下變換方案

Maxim公司的MAX19994A是雙路RF下變換器,RF范圍從1200MHz到2000MHz,LO范圍從1450MHz 到 2050MHz,IF范圍從50MHz到500MHz,典型的轉換增益為8.4dB,典型的噪音為9.8dB,輸入IP3典型值為+25dBm,輸入1dB壓縮點為+14dBm,單電源5.0V 或3.3V工作,主要用在WCDMA/LTE,TD-SCDMA,GSM/EDGE和cdma2000M 無線基站,無線本地回路(WLL),固定寬帶無線接入,私人移動電臺和軍用系統.本文介紹MAX19994A主要特性,功能方框圖,以及典型應用電路圖和所用元件表.

The MAX19994A dual-channel downconverter is designed to provide 8.4dB of conversion gain, +25dBm input IP3, +14dBm 1dB input compression point, and a noise figure of 9.8dB for 1200MHz to 2000MHz diversity receiver applications. With an optimized LO frequency range of 1450MHz to 2050MHz, this mixer supports both high- and low-side LO injection architectures for the 1200MHz to 1700MHz and 1700MHz to 2000MHz RF bands, respectively.

In addition to offering excellent linearity and noise performance, the device also yields a high level of component integration. This device includes two double-balanced passive mixer cores, two LO buffers, a dual-input LO selectable switch, and a pair of differential IF output amplifiers. Integrated on-chip baluns allow for singleended RF and LO inputs. The MAX19994A requires a nominal LO drive of 0dBm and a typical supply current of 330mA at VCC = 5.0V, or 264mA at VCC = 3.3V.

The MAX19994A is pin compatible with the MAX9985/ MAX9995/MAX19985A/MAX19993/MAX19995/ MAX19995A series of 700MHz to 2500MHz mixers and pin similar with the MAX19997A/MAX19999 series of 1850MHz to 4000MHz mixers, making this entire family of downconverters ideal for applications where a common PCB layout is used across multiple frequency bands.

The device is available in a 6mm x 6mm, 36-pin thin QFN package with an exposed pad. Electrical performance is guaranteed over the extended temperature range, from TC = -40NC to +85NC.

MAX19994A主要特性:

1200MHz to 2000MHz RF Frequency Range

1450MHz to 2050MHz LO Frequency Range

50MHz to 500MHz IF Frequency Range

8.4dB Typical Conversion Gain

9.8dB Typical Noise Figure

+25dBm Typical Input IP3

+14dBm Typical Input 1dB Compression Point

68dBc Typical 2LO - 2RF Spurious Rejection at PRF = -10dBm

Dual Channels Ideal for Diversity Receiver application

47dB Typical Channel-to-Channel Isolation

Low -6dBm to +3dBm LO Drive

Integrated LO Buffer

Internal RF and LO Baluns for Single-Ended Inputs

Built-In SPDT LO Switch with 48dB LO-to-LO Isolation and 50ns Switching Time

Pin Compatible with the MAX9985/MAX9995/MAX19985A/MAX19993/MAX19995/MAX19995A Series of 700MHz to 2200MHz Mixers

Pin Similar to the MAX19997A/MAX19999 Series of 1850MHz to 4000MHz Mixers
Single 5.0V or 3.3V Supply

External Current-Setting Resistors Provide Option for Operating Device in Reduced-Power/Reduced-Performance Mode

MAX19994A應用:

WCDMA/LTE Base Stations

TD-SCDMA Base Stations

GSM/EDGE Base Stations

cdma2000M Base Stations

Wireless Local Loop

Fixed Broadband Wireless Access

Private Mobile Radios

Military Systems


圖1.MAX19994A功能方框圖

圖2.MAX19994A典型應用電路圖

所用元件值: