A Realization of Low-Frequency Active RC Second-Order Band-Pass Circuit with Stable High Q

Nobuyuki MASUMI
Masataka NAKAMURA

Publication
IEICE TRANSACTIONS on Electronics   Vol.E88-C    No.6    pp.1172-1179
Publication Date: 2005/06/01
Online ISSN: 
DOI: 10.1093/ietele/e88-c.6.1172
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Analog Circuit and Device Technologies)
Category: Active Filter
Keyword: 
active RC filter,  ultralow/low-frequency signal,  analog signal processing,  capacitance multiplier,  high Q,  

Full Text: PDF(552.4KB)>>
Buy this Article


Summary: 
In this paper, we propose a circuit configuration for the low-frequency second-order active RC BPF (band pass filter) which has stable high Q. This proposed circuit is a high Q low-frequency one with a small capacitance, which is realized by applying an output capacitance multiplier to the circuit. Then a detailed circuit analysis is performed for the proposed circuit. From the simulation results of fo and Q for various combinations of circuit element values, we can confirm that the circuit realization of a center frequency of several Hz is possible by employing chip condensers of dozens of nF. The bread-board circuit of this configuration is confirmed to have small temperature dependences of fo and Q by the experiment. It is also clarified from detailed noise analysis and noise measurement that the circuit noise is sufficiently maintained at a low level.