Linear LTM9003数字预失真(DPD)接收方案
Linear公司的LTM9003是12位数字预失真接收器子系统,包括了下变换混频器(频率范围从400MHz到3.8GHz),宽带滤波器和模数转换器(ADC).12位的ADC取样速率高达250Msps,中频(IF)为184MHz,信号带宽高达125MHz. LTM9003带通滤波器125Mz,通带波纹小于0.5dB.输入噪音–145.5dBm/Hz,IIP3为25.8dB,单端RF和LO端口阻抗为50欧姆.主要用于宽带接收器,宽带仪表, 数字预失真(DPD)接收器,发送观测通路接收器.本文介绍了LTM9003的主要特性, 简化方框图, 典型应用电路以及RF输入电路图.
LTM9003 12-Bit Digital Pre-Distortion Receiver Subsystem
The LTM9003 is a 12-bit digital pre-distortion receiver subsystem for the transmit path of cellular basestations. Utilizing an integrated system in a package (SiP) technology, it includes a downconverting mixer, wideband filter and analog-to-digital converter (ADC). The system is tuned for an intermediate frequency (IF) of 184MHz and a signal bandwidth of up to 125MHz. The 12-bit ADC samples at rates up to 250Msps. Contact Linear Technology regarding customization.
The high signal level downconverting active mixer is optimized for high linearity, wide dynamic range IF sampling applications. It includes a differential LO buffer amplifier driving a double-balanced mixer. Broadband, integrated transformers on the RF and LO inputs provide single ended 50Ω interfaces. The RF and LO inputs are internally matched to 50Ω from 1.1GHz to 1.8GHz.
The CLK input controls converter operation and may be driven differentially or single-ended. An optional clock duty cycle stabilizer allows high performance at full speed for a wide range of clock duty cycles.
LTM9003主要特性:
Fully Integrated Receiver Subsystem for Digital Pre-Distortion Applications
Down-Converting Mixer with Wide RF Frequency Range: 400MHz to 3.8GHz
125MHz Wide Bandpass Filter, <0.5dB Passband Ripple
Low Power ADC with Up to 12-Bit Resolution, 250Msps Sample Rate
–145.5dBm/Hz Input Noise Floor, 25.8dBm IIP3
1.5W Total Power Consumption
50Ω Single-Ended RF and LO Ports
Internal Bypass Capacitance, No External Components
ADC Clock Duty Cycle Stabilizer
11.25mmx15mm LGA package
LTM9003应用:
Transmit Observation Path Receivers
Digital Pre-Distortion (DPD) Receivers
Wideband Receiver
Wideband Instrumentation
图1.LTM9003简化方框图
图2.LTM9003典型应用电路
图3.LTM9003 RF输入电路图
图4.LTM9003变压器驱动ENC+/ENC-电路图