The LMX2347SLEX is a high-performance, low-power dual frequency synthesizer from National Semiconductor (now Texas Instruments). Designed for a wide range of wireless applications, this device integrates two independent frequency synthesizers into a single chip. Each synthesizer features a phase-locked loop (PLL) with a high-resolution fractional-N divider, enabling precise frequency control and low phase noise. The device also includes integrated voltage controlled oscillators (VCOs), simplifying system design and reducing external component count.

Applications

• Wireless LAN (WLAN)
• Cordless Phones
• Cellular and PCS Handsets
• Satellite Communication Systems
• Wireless Data Transmission

Features

• Dual Frequency Synthesizers
• Fractional-N Architecture
• Integrated VCOs
• Frequency Range: Up to 2.4 GHz
• Low Phase Noise
• Low Supply Voltage: 2.7V to 3.3V
• Power-Down Mode
• Serial Interface for Programming

Benefits

• Precise Frequency Control: Fractional-N architecture allows for fine-grained frequency adjustment and channel spacing.
• Dual Synthesizers: Enables simultaneous operation at two different frequencies, simplifying dual-band system design.
• Low Phase Noise: Minimizes unwanted spurious signals and improves signal quality in wireless communication.
• Integrated VCOs: Reduces external component count and simplifies PCB layout.
• Low Power Consumption: Extends battery life in portable applications.

The LMX2347SLEX is designed for ease of use, featuring a serial interface for programming the PLL parameters. The power-down mode reduces current consumption when the device is not actively synthesizing frequencies. The small package size is ideal for space-constrained applications. Proper power supply decoupling is crucial for minimizing noise and ensuring stable operation. The fractional-N architecture allows for fine frequency steps, essential for meeting the requirements of modern wireless standards. Careful consideration of the loop filter design is necessary to optimize the PLL performance for a given application. Application notes and design tools are available from Texas Instruments to assist with the design process.