High-frequency linear transformation elliptic filters employing minimum number of OTAs

High-frequency linear transformation (LT) elliptic filters employing a minimum number of operational transconductance amplifiers (OTAs) and capacitors are presented. Based on the LT, an OTA-C elliptic filter can be realised efficiently by adding capacitors to the relative all-pole filter as passive prototype counterparts. The canonical filter with all nodes having a desired capacitance, which is suitable for high-frequency operation, is developed. As an example, a new third-order elliptic lowpass filter is synthesised. Experimental results arc obtained to verify the theoretical analysis. Furthermore, the proposed circuit can be extended to higher-order filters.