滤波器_(正负2.5V电源)_A_4-MHz_CMOS_Continuous-Time_Filter_with_On-Chip_Automatic_Tuning.pdfVIP

750 IEEE JOURNAL OF SOLID-STATE CIRCUITS, VOL. 23, NO. 3, JUNE 1988 A 4-MHz CMOS Continuous-Time Filter with On-Chip Automatic Tuning FRAN~OIS KRUMMENACHER AND NORBERT JOEHL ,4bstmct —This paper presents a third-order elliptic low-pass continu- this integrator configuration potentially achieves the best ous-time filter with a 4-MHz cutoff frequency, integrated in a 3- pm p-well high-frequency performance because it makes use of a CMOS process. The design procedure is based on the direct simulation of single source-coupled differential pair to implement the a doubly terminated LC ladder filter by means of capacitors and fully voltage-to-current converter function (as opposed to con- balanced, current-controlled transconductance amplifiers with extended linear range. The on-chip automatic toning circuit uses a phase-locked loop figurations with multistage operational amplifiers which implemented with an 8.5-MHz controlled oscillator that matches a specific suffer from large amounts of excess phase at high two-integrator loop of the filter. The complete circuit features 70-dB frequency, causing unacceptable