A fully integrated high-pass filter for very low frequency applications

Author

De Lima, Jader A. ; Pimenta, Wallace A.

Author_Institution

Freescale Semicond., Brazil Semicond. Technol. Center, Campinas, Brazil

fYear

2009

fDate

24-27 May 2009

Firstpage

257

Lastpage

260

Abstract

A fully-integrated high-pass CMOS filter with Hertz/sub-Hertz break frequencies is presented. The new common-mode voltage is set by a simple feedback loop comprising a servo-amplifier and two common-drain transistors. No bulky resistors are required, making the approach compact and fully integrated. Since the input current is limited to tens of pA, the filter equivalent input-resistance reaches GOmega-range, whereas demanding relatively small layout area. The circuit was designed according to a 0.35 mum CMOS process and 1.5 V-supply. For a 33 pF-coupling capacitor, the simulated cut-off frequency varies from 0.085 Hz to 1.55 Hz, so that the AC-coupler emulates an equivalent resistor of 3.1 GOmega @ 85degC. THD is -72 dB and SNR= 89.2 dB for a 300 mV-amplitude signal. Filter consumption is below 1.05 muW.

Keywords

CMOS integrated circuits; high-pass filters; AC-coupler; CMOS filter; amplitude signal; capacitance 33 pF; common-drain transistor; common-mode voltage; coupling capacitor; feedback loop; filter equivalent input-resistance; frequency 0.085 Hz to 1.55 Hz; fully integrated high-pass filter; power 1.05 muW; resistance 3.1 Gohm; resistor; servo-amplifier; size 0.35 mum; temperature 85 degC; very low frequency application; voltage 1.5 V; voltage 300 mV; Capacitors; Circuits; Distortion; Feedback loop; Filters; Frequency; MOSFETs; Resistors; Signal processing; Voltage;

fLanguage

English

Publisher

ieee

Conference_Titel

Circuits and Systems, 2009. ISCAS 2009. IEEE International Symposium on

Conference_Location

Taipei

Print_ISBN

978-1-4244-3827-3

Electronic_ISBN

978-1-4244-3828-0

Type

conf

DOI

10.1109/ISCAS.2009.5117734

Filename

5117734