公开(公告)号：WO1998023071A1

公开(公告)日：1998-05-28

申请号：PCT/US1997021469

申请日：1997-11-21

Applicant: ADVANCED MICRO DEVICES, INC.

Inventor： ADVANCED MICRO DEVICES, INC. ,  JANESCH, Stephen, T. ,  SCHINZLEIN, Paul

IPC: H04L27/227

CPC classification number: H04L27/2275 ,  H03L7/093 ,  H03L7/0991 ,  H03L7/107 ,  H03L7/146 ,  H04B1/707 ,  H04L1/24 ,  H04L7/0334 ,  H04L27/22 ,  H04L27/2273 ,  H04L27/2277 ,  H04L2027/0028 ,  H04L2027/0046 ,  H04L2027/0067 ,  H04L2027/0069

Abstract: A digital loop filter in the carrier-recovery loop of a digital communications receiver. The recovery loop is a PLL that keeps the receiver oscillator locked to the carrier wave, and the loop filter provides control over the PLL's frequency response by conditioning an error signal that is fed back to the receiver oscillator. In the present invention, the error signal is a digital signal, and the loop filter is implemented in digital hardward. With this implementation the characteristics of the loop filter are determined by logic design rather than by physical features of analog components, thereby giving this filter a more precise function than one with analog integrators. This implementation is also immune to the low tolerances typical of the manufacturing process for analog devices (especially on monolithic circuits), and is more easily adjusted than its analog counterparts. Two gain coefficients characterize the loop filter in the present invention. These gain coefficients are chosen to be powers of two, simplifying the process of multiplying them with the digital error signal. The gain coefficients are read from a memory, making the loop filter easily programmable. By changing the gain coefficients during operation of the receiver, the carrier-recovery loop can be placed in one of the several operating modes, including acquisition, tracking, and hold. The receiver can be configured with the appropriate values of the gain coefficients for each operating mode during the initial assembly and during subsequent reconfigurations.

Abstract translation: 数字通信接收机的载波恢复回路中的数字环路滤波器。 恢复环路是将接收器振荡器锁定到载波的PLL，环路滤波器通过调节反馈到接收机振荡器的误差信号来提供对PLL频率响应的控制。 在本发明中，误差信号是数字信号，环路滤波器以数字硬件方式实现。 通过这种实现，环路滤波器的特性由逻辑设计而不是模拟组件的物理特性决定，从而使得该滤波器比具有模拟积分器的功能更精确。 该实现也不受模拟器件（特别是单片电路）的制造工艺典型的低容差的影响，并且比其模拟器件更容易调整。 两个增益系数表征本发明中的环路滤波器。 这些增益系数被选为2的幂，简化了与数字误差信号相乘的过程。 从存储器读取增益系数，使得环路滤波器易于编程。 通过在接收机操作期间改变增益系数，载波恢复回路可以放置在几种操作模式之一，包括采集，跟踪和保持。 可以在初始组装期间和随后的重新配置期间，为每个操作模式的接收机配置适当的增益系数值。