Bandpass amplifier and receiver using bandpass amplifier

摘要

The present application relates to an active bandpass amplifier comprising a single stage operational amplifier, a bridged "T" network single frequency elimination filter in the negative feedback path of the amplifier and a phase shift correcting capacitor associated with the bridged "T" network single frequency elimination filter to effect a phase shift sufficient to maintain an appropriate feedback such that the amplifier is stable. The bridged "T" network single frequency elimination filter in conjunction with the circuit capacities and phase shifts in the integrated circuits introduces a phase shift which would result in the amplifier oscillating when the network is placed in the feedback path and the corrective capacitor effects a corrective phase shift to render the amplifier stable. Such a bandpass amplifier allows high gain and high "Q" and the gain is many times higher than that of a conventional single stage amplifier where gain is typically limited to approximately 5 and the "Q" is limited to about 25. In the present case, this bandpass amplifier is capable of gains of greater than 10 and substantially higher "Q". Such an amplifier is advantageously used in a receiver and in a signalling system. The high gain capablility of the receiver is particularly advantageous in a mining environment where the receiver can be used as part of a signalling system.