Linear LTC6400-20高速放大器应用方案

Linear公司的LTC6400-20高速放大器应用方案的-3dB带宽为1.8GHz,具有低噪音和低失真性能,特别设计用来驱动12位,14位或16位ADC,目标应用在DC到300MHz的信号处理,以及通用的宽带增益放大电路.本文介绍了LTC6400-20的主要性能特性,方框图以及典型的应用电路图.

The LTC 6400-20 is a high-speed differential amplifier targeted at processing signals from DC to 300MHz. The part has been specifically designed to drive 12-, 14- and 16-bit ADCs with low noise and low distortion, but can also be used as a general-purpose broadband gain block.

The LTC6400-20 is easy to use, with minimal support circuitry required. The output common mode voltage is set using an external pin, independent of the inputs, which eliminates the need for transformers or AC-coupling capacitors in many applications. The gain is internally fixed at 20dB (10V/V).

The LTC6400 is a low noise and low distortion fully differential op amp/ADC driver with:
• Operation from DC to 1.8GHz (–3dB bandwidth)
• Fixed gain of 10V/V (20dB)
• Differential input impedance 200Ω
• Differential output impedance 25Ω
• On-Chip 590MHz output filter

The LTC6400-20 saves space and power compared to alternative solutions using IF gain blocks and transformers. The LTC6400-20 is packaged in a compact 16-lead 3mm × 3mm QFN package and operates over the –40°C to 85°C temperature range.
Frequency

■ 1.8GHz –3dB Bandwidth
■ Fixed Gain of 10V/V (20dB)
■ –94dBc IMD3 at 70MHz (Equivalent OIP3 = 51dBm)
■ –65dBc IMD3 at 300MHz (Equivalent OIP3 = 36.5dBm)
■ 1nV/√Hz Internal Op Amp Noise
■ 2.1nV/√Hz Total Input Noise
■ 6.2dB Noise Figure
■ Differential Inputs and Outputs
■ 200Ω Input Impedance
■ 2.85V to 3.5V Supply Voltage
■ 90mA Supply Current (270mW)
■ 1V to 1.6V Output Common Mode Voltage, Adjustable
■ DC- or AC-Coupled Operation
■ Max Differential Output Swing 4.4VP-P
■ Small 16-Lead 3mm × 3mm × 0.75mm QFN Package

应用:
■ Differential ADC Driver
■ Differential Driver/Receiver
■ Single Ended to Differential Conversion
■ IF Sampling Receivers
■ SAW Filter Interfacing

方框图:



典型应用电路图(Test Circuit A):