Image-rejection receiver using on-chip active notch filters for 2.4-GHz band wireless communication applications

A high image rejection SiGe low noise amplifier using passive notch filter

“…From (5) and (6), the zero is same as [2,3,4,5] and the pole is determined by notch components. It is interesting to find that C Extra is not located in (6); this is because this capacitor is used to attenuate the impact of source resistance, making the base terminal of Q 1 act like an ac ground at desired frequency.…”

“…[3] introduces active notch filter to compensate parasitic resistance of on-chip inductor to achieve a large Q notch filter. This is, however, not preferred because negative impedance means more power consumption.…”

“…Good IRR can ensure a good image rejection, but poor input match at operating frequency may degrade the useful signal injection performance [8,9]. Attentions should be made that [3] adopts an extra capacitor to tune the operating frequency without affecting the image frequency, this is, theoretically, can also be utilized in passive filters. In order to optimize the input match as well as save power [10], a new passive IR filter is introduced.…”