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Patent

Impedance transformation network for a SAW filter

Muterspaugh Max Ward, +1 more
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TLDR
In this paper, an impedance transformation network is coupled between the output terminal of an amplifier and the input terminal of a SAW filter for increasing the effective load impedance of the amplifier and for decreasing the output impedance of a drive arrangement.
Abstract: 
The IF section of a television receiver includes an amplifier having an input terminal for receiving an IF signal and an output terminal at which an amplified version of the IF signal is developed and a SAW filter having two input terminals, one of which is connected to AC signal ground, for receiving the amplified IF signal and an output terminal for providing a modified IF signal having a bandpass characteristic determined by the SAW filter. An impedance transformation network is coupled between the output terminal of the amplifier and the input terminal of the SAW filter for increasing the effective load impedance of the amplifier and for decreasing the output impedance of the drive arrangement. The former aspect of the impedance transformation network allows a transistor with lower current supplying capabilities to be employed. The latter aspect of the impedance transformation network tends to reduce undesired voltages developed in response to reflections between the transducers of the SAW filter. Specifically, the impedance transformation network includes an inductor connected between the output terminal of the amplifier and the AC signal ground, a capacitor connected between the output terminal of the amplifier and the input terminal of the SAW filter and a resistor connected between the input terminal of the SAW filter and the AC signal ground. Desirably, the capacitance of the capacitor is in the same order of magnitude as the input capacitance of the SAW filter and the inductance of the inductor is selected to provide a resonance with the effective capacitance in the passband.

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Citations
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Patent

Intermediate frequency circuit for cellular telephone transceiver using surface acoustic wave filter

Sean M. Broderick
TL;DR: In this article, a double-mode resonator SAW bandpass filter with a bandwidth of approximately 30 kilohertz and a noise figure less than 5 dbm is used to produce a filtered third signal in response to the second signal.
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FM High-fidelity processor

Hong Yu, +1 more
TL;DR: In this article, a processor is proposed to provide high-quality audio signals from television sound channels by signal recovery using induced intermodulation between the picture carrier and the sound subcarrier signal.
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Stable low cost 4.5 MHz remodulator

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Digital terrestrial TV tuner

Shadwell Peter Wardlow
TL;DR: In this article, the authors proposed a digital terrestrial TV tuner consisting of a voltage tunable filter, an amplifier, a buffer amplifier, and a SAW filter stage comprising a series of connected SAW filters for filtering the IF signal, a variable gain amplifier for amplifying the filtered IF signal and a mixer for down converting the amplified IF signal to a base band signal before passing it to an analogue to digital convertor.
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Apparatus for driving a mechanical resonator from a high impedance source

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TL;DR: In this paper, a high impedance signal source (22) driving a relatively low input impedance mechanical resonating device (42) such as a ceramic filter having an input impedance which varies with frequency.
References
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Patent

SAW Filter preamplifier

Gerald E. Theriault
TL;DR: In this article, a preamplifier is provided which couples a television tuner to a surface acoustic wave (SAW) filter and amplifies the I.F. signals supplied by the tuner so as to overcome the signal losses of the SAW filter.
Patent

Inter-stage coupling circuit for neutralizing internal feedback in transistor amplifiers

Karol Siwko
Patent

IF Bandpass shaping circuits

Max W. Muterspaugh, +1 more
TL;DR: An IF bandpass shaping circuit for use with a television receiver having a tuner for providing intermediate frequency signals comprises a surface acoustic wave (SAW) filter coupled to the tuner as mentioned in this paper.
Patent

Electric circuit using surface acoustic wave device

Hideharu Ieki, +1 more
TL;DR: In this paper, an impedance converting circuit is inserted in series between the signal input circuit and the input transducer and/or between the output transducers and the signal output circuit.
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Interface system for surface wave integratable filter

Gary A. Jones
TL;DR: In this paper, a system for interfacing a SWIF with a tuner and an amplifier in the IF section of a television receiver is described, where the output of the SWIF is coupled to an amplifier which has a low, untuned input impedance to establish a mismatch between SWIF and the amplifier to therey reduce triple-transit effects associated with SWIF.