Linear LTC5598 5-1600MHz高线性正交调制方案

Linear 公司的LTC5598是5-1600MHz高线性正交I/Q调制器,允许采用差分基带I和Q信号的RF信号进行直接调制. LTC5598支持点对点微波连接, GSM, EDGE, CDMA, 700MHz 波段LTE,CDMA2000, CATV应用和其它系统应用,140MHz的IP3为+27.7dBm, 900MHz的IP3为+22.9dBm.本文介绍了LTC5598的主要特性,方框图,典型应用电路和评估板电路.

The LTC5598 is a direct I/Q modulator designed for high performance wireless applications, including wireless infrastructure. It allows direct modulation of an RF signal
using differential baseband I and Q signals. It supports point-to-point microwave link, GSM, EDGE, CDMA, 700MHz band LTE, CDMA2000, CATV applications and other systems. It may also be confi gured as an image reject upconverting mixer, by applying 90°phase-shifted signals to the I and Q inputs.

The I/Q baseband inputs consist of voltage-to-current converters that in turn drive double-balanced mixers. The outputs of these mixers are summed and applied to a buffer, which converts the differential mixer signals to a 50Ω single-ended buffered RF output. The four balanced I and Q baseband input ports are intended for DC coupling from a source with a common-mode voltage level of about 0.5V. The LO path consists of an LO buffer with single-ended or differential inputs, and precision quadrature generators that produce the LO drive for the mixers. The supply voltage range is 4.5V to 5.25V, with about 168mA current.

主要特性:

Frequency Range: 5MHz to 1600MHz

High Output IP3: +27.7dBm at 140MHz +22.9dBm at 900MHz

Low Output Noise Floor at 6MHz Offset: No Baseband AC Input: –161.2dBm/Hz

POUT = 5.5dBm: –160dBm/Hz

Low LO Feedthrough:–55dBm at 140MHz

High Image Rejection:–50.4dBc at 140MHz

Integrated LO Buffer and LO Quadrature Phase Generator

50Ω Single-Ended LO and RF Ports

>400MHz Baseband Bandwidth

24-Lead QFN 4mm.4mm Package

Pin-Compatible with Industry Standard Pin-Out

Shut-down Mode

主要应用 :

Point-to-Point Microwave Link

Military Radio

Basestation Transmitter GSM/EDGE/CDMA2K

700MHz LTE Basestation Transmitter

Satellite Communication

CATV/Cable Broadband Modulators

13.56MHz/UHF RFID Modulator



图1.LTC5598方框图



图2. LTC5598典型应用电路



图3. LTC5598评估板电路图