10.7-MHz IF amplifier

This is 10.7-MHz IF amplifier circuit. This circuit is used in many application such as cell phone base station receivers (final IF) and FM broadcast receivers. The ceramic filter that is used in this circuit are cheap and available in a variety of insertion losses and banwidths. This circuit uses a 230-kHz bandwidth filter SFELA10M7GA00-B0 and the gain stage. Here […]

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High Impedance Low Capacitance Buffer/Amplifier

These are circuits of high impedance low capacitance buffer and high impedance low capacitance¬† amplifier. First figure is a high impedance low capacitance buffer circuit, it uses the 2N446 JFET that features low input capacitance. The feedback buffer a wide-band unity gain amplifier is made from this 2N446 JFET. Here is the circuit : The second figure is high impedance […]

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JFET-Bipolar Cascode Circuit

This is JFET-bipolar cascode circuit. It will provide full video output for the CRT cathode drive. The gain of this circuit is about 90. Here is the circuit : This circuit employs 2N4091 JFET to solve Miller capacitance problems using cascode configuration. It will alow direct drive from the video detector. The video amplifier will not amplify the 45MHz sound […]

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Voltage Controlled Variable Gain Amplifier

This is a circuit of voltage controlled variable gain amplifier. This circuit uses 2N4391 that will provide a low Rds(on) less than 30 Ohm. This circuit also uses a tee attenuator, that will provide optimum dynamic linear range for attenuation. We can obtain the attenuation greater than 100dB at 10MHz by providing proper RF construction techniques. Here is the circuit […]

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FET Cascode Video Amplifier

This is a simple  FET Cascode Video Amplifier circuit. This circuit has some features, they are reduction of feedback to almost zero and very low input loading. Here is the circuit: This circuit uses 2N3823 because it has high Yfs and low capacitance. RL and load capacitance limits bandwidth of the amplifier. [Source: National Semiconductor Application Note]

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