Passive enhancement of resonator Q in microwave notch filters

Abstract

Abstruct -The lumped-element bridged-T notch fdterThe purpose of this paper is to extend Bode's Concept is extended to reciprocal distributed-element bridged-T notch filter concept to reciprocal circuits that fdter employing singlemode resonators is described that enhances the effective resonator Qu by a factor of 325, while ,a different microstrip fdter topology with a Mple-mode bdance and phase cancellation [61 can take the place of resonator is described that enhances the effective resonator Bode's impedance balance concept. The result is Qu by a factor of 89. The new notch filters can be either essentially the passive enhancement of resonator effective partly reflective or fully absorptive within the stopband. Q~ ( Q , ,~~) ) . A microstrip bridged-T topology is used toAdditional enhanced+, notch fdter topologies, such as a notch mter, that include at least two illustrate how one can obtain quasi-infinite attenuation at resonances and at least two signal paths are suggested.single frequencies using passive lossy distributed components. Also, it is shown that the technique can be generalized to other topologies that include at least two resonances and at least two signal paths.fflters. A prototype microship bfidged-T notch include distributed elements. It is demonstrated that, for distributed element circuits, the concepts of attenuation

An Image-Reject Low-Noise Amplifier with Passive Q-Enhanced Notch Filters

“…Referring to Figure 2, we can deduce that the portion of the drain current of M1 that reaches the source of M2 is given by frequency. Reduction in gain at the signal frequency in an IR-LNA with a filter at the drain of M1 was mentioned in [5]. In the proposed IR-LNA, this is more pronounced due to the two signal paths to ground through 1 R and 2 R .…”

“…An active notch filter is used in [1,4] while [2,3] use passive notch filters. We have used a twin-T notch-filter as described in [5]. Fig.…”

Non Linear Bandstop Filters A New Method of Frequency Selective Limiting

“…Therefore, it is inevitable to expect a low Q U Bandstop Limiter. However, the Q U of the Bandstop Limiter can be effectively improved by applying the enhanced-Q U circuit described in [5,6]. …”

Perfectly-matched bandstop filters using lossy resonators

“…The present work utilizes a passive approach to implement a narrowband bandstop filter with theoretically infinite stopband attenuation, while being perfectly matched in both the passband and stopband. This work builds upon the perfect-notch concept presented in [4] by showing that an identical transfer function can be realized with lossy allpass networks, which by nature are perfectly matched. Such networks could theoretically be placed in cascade to realize more advanced transfer functions.…”