A monolithic video frequency filter using NIC-based gyrators

A filter system for analog video signal processing is discussed. This system is composed of a variable time-constant active RC filter part with balanced-type negative impedance converters (NICs) and an automatic tuning circuit part using a PLL. The system is implemented by a conventional junction-isolated 15- mu m bipolar process with n-p-n transistors of f/sub T/=400 MHz; features low production cost; and it uses an automatic tuning scheme with better accuracy in response than previous systems. A filter system with a passband from 3.7 to 5.2 MHz, and which operates from a single 5-V supply, was implemented by the bipolar process. Experimental results obtained for the filter system are given.<
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