مدار مجتمع (آی سی) آی سی‌کاربرد ویژه

Product Attributes

Introduction

The AD880 is a monolithic integrated circuit designed for applications in optical disc drive servo/read systems. The AD880 consists of four matched transimpedance amplifiers (A, B, C, D) with selectable transimpedance values of 36 kΩ or 120 kΩ. Each basic transimpedance stage comprises a 10 kΩ transimpedance amplifier driving a programmable X1 or X3.3 buffer. Each stage is configured to minimize noise and noise peaking. To further improve overall SNR performance, an external capacitor can be added between the transimpedance amplifier and the programmable buffer to implement a first-order low-pass filter. The AD880 is stable across the full range of input source capacitance. To ensure stability and maximize bandwidth, internal compensation capacitors in the programmable buffers are appropriately modified in both transimpedance modes. Fast write recovery is achieved through the transimpedance sampling function. The "sample" function prevents channel saturation during write operations. The "sampling capacitor" also serves the dual purpose of providing low-pass filtering. In addition, the device contains three offset-trimming summing amplifiers with a bandwidth of 30 MHz. One amplifier provides a four-input summing output that can be low-pass filtered prior to driving a normalization divider. The other two summing amplifiers generate tracking and focus outputs.

Applications

• Servo/read system applications for optical disc drives