Abstract: A circuit model of electronically tunable operational transconductance amplifier（EOTA） based on bipolar technology is described.Multi-input and single-output universal filter used by EOTA and grounded capacitors has been designed.The proposed circuit provides lowpass,highpass,bandpass,bandstop voltage responses at a high impedance input terminal.The arbitrary high order filters are easy to generate by cascading the filter.The circuit parameters ω₀ and Q can be set orthogonally by adjusting the bias current or voltage.The filter has high sensitivity,wide linearity and the circuit parameters matching are eliminated.The working principle of Biquadratic Filters and the method of generating high order filters with EOTA are analyzed.The two filter functions are discussed.The theoretical analyses are verified by experiments.