New approach of tunable notch filter for blocker suppression of multi-mode wireless devices

Abstract

This In multi-mode multi-band wireless devices, the notch filter is necessary to avoid coexistence problem. N path switched RC networks will give precise notch frequency. Even though N path switched RC networks provide high linearity and high Q factor, they have some non idealities like switch resistance, clock rise-fall time, harmonic mixing, clock phase noise effect, etc. In order to overcome these limitations, a novel approach of notch filter is designed in CMOS 180nm technology by using G <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</sub> C cells with poly phase signalling. It will consume very less power as compared to N path frequency shifting notch filter(designed by using mixers and local oscillators). In this paper, The frequency shifting has done by using operational trans-conductance amplifier cells and with the first order high pass filter of in-phase and quadrature phase. Hence need of local oscillator is removed. The tuning range of this new filter is 1MHz-300MHz. The rejection at the notch frequency is 25-30 dB. The OTA used in this paper consumes 49 μ Watt and notch filter consume 432 μ Watt power.