提高可编程增益放大器准确度的一种简单方法

A Simple Way to Improve the Gain Accuracy of Programmable Gain Amplifier

数字的可编程性已经成为复杂的混合信号系统里的一个非常必要的特征。可编程增益放大器已广泛应用于各种各样的系统中,它主要用于优化整个系统的动态范围。由于它是用数字信号控制并且有很大的增益范围,所以需要用开关来选择使动态范围最大的那个增益。这篇论文讲述了一个简单的方法来提高增益的准确度。这个方法采用开关的并联和电阻的组合作为一个单元,它能使可编程增益放大器的增益和开关的可变电阻无关。我设计了一个可编程增益放大器验证了这个方法的可行性。它用0.18umCMOS技术生产,增益范围是-28～35dB,步长是1dB,有6位数字信号控制,仿真结果表明了精度可达到0.05dB。

Digital programmability is becoming an essential feature for complex mixed - signal systems. Programmable Gain Amplifier （PGA） is used in a variety of applications to optimize the dynamic range of the overall system. Being controlled by digital bits and has a wide range of the gain, PGA needs the switches to select the gain which can get the best dynamic range. This paper presents a simple way to improve the gain accuracy of PGA. It uses the combination of the parallel connections of the switches with the resistance as a unit which can make the gain of the PGA independent of the variable resistances of the switches. An example of the PGA is used to verify the new method. Fabricated in a 0.18 um CMOS technology, the PGA provides 6 - bit resolution with large gain control range： -28 N 35dB. The gain step is 1 dB and the simulation results show the accuracy is less than 0. 05dB.