Design of odd nth-order elliptic high-pass filters employing OTRAs

Two new analytical synthesis methods are proposed for synthesising an nth odd-order elliptic high-pass (HP) filter using operational trans-resistance amplifiers (OTRAs). The analytical synthesis scheme is based on the assumption of infinite trans-resistance Rm for the OTRA. The H-spice simulations of the realised elliptic third-order HP filters show that the realisation using less number of OTRAs has a performance better than that which uses more number of OTRAs, as is to be expected in view of the assumption that Rm is infinite, when in fact it is finite in practice. However, it is shown that by slightly adjusting a single resistor, the amplitude–frequency response can be made close to the theoretical response.