The switched-resistor (S-R) approach is becoming more and more popular among integrated circuits designers because it allows the implementation of very high equivalent resistances in CMOS circuits. When using this technique, the value of a reference poly resistor is multiplied by a factor dependent on the duty cycle of the clock signal. To achieve resistance multiplication factors higher than 100, the value of the duty cycle has to be reduced below 0.01, but in this case the effects of parasitic components are not negligible anymore and the value of the equivalent resistance tends to saturate at a maximum value. In this paper, we present a distributed switched-resistor approach that aims to strongly mitigate the effect of parasitic capacitances on the value of the equivalent resistance even when exploiting very small values for the duty cycle, thus allowing resistance multiplication factors up to a few thousands. As a validation of this approach, we consider the implementation of a high Q biquad filter for neural recording applications and compare the conventional S-R technique against the proposed distributed S-R approach in terms of the maximum achievable Q factor.

开关电阻器 (SR) 方法在集成电路设计人员中变得越来越流行，因为它允许在 CMOS 电路中实现非常高的等效电阻。使用这种技术时，参考多晶硅电阻的值乘以一个取决于时钟信号占空比的因子。为了实现高于 100 的电阻倍增系数，占空比值必须降低到 0.01 以下，但在这种情况下，寄生元件的影响不再可忽略，等效电阻值趋于饱和在最大值。在本文中，我们提出了一种分布式开关电阻器方法，旨在强烈减轻寄生电容对等效电阻值的影响，即使在使用非常小的占空比值时，从而允许电阻倍增系数高达几千。作为对这种方法的验证，我们考虑为神经记录应用实施高 Q 双二阶滤波器，并在最大可实现 Q 因子方面将传统 SR 技术与提议的分布式 SR 方法进行比较。