HIGH FREQUENCY CMOS BUFFER AMPLIFIER
Original Publication Date: 1996-Nov-01
Included in the Prior Art Database: 2002-May-01
It is ofien desirable to use CMOS counters and prescalers to measure the frequency of an analog (sinusoidal) signal, or for using such a signal as a clock for CMOS logic circuits. CMOS logic requires signal swings of at least a few hundred millivolts about the half-supply point. Frequently, a discrete transistor and LC tank circuit AC coupled to an input, biased at half-supply, provide amplification of low amplitude, high frequency signals. Trimming requirements ofthe LC tank lead to manufacturability difficulties and cost increases, and large signals in an LC tank create RF interference. A preferable approach is to implement a fully integrated broad- band amplifier.