High speed frequency acquisition apparatus for microwave synthesizers

Claim 1

In a microwave synthesizer, a high speed frequency acquisition apparatus comprising in combination: frequency detector means receiving a first and second frequency and providing either a high or low output, said high output corresponds to said first frequency being greater than said second frequency, said low output corresponds to said first frequency being less than said second frequency, means for frequency differencing receiving said first and second frequency, said frequency differencing means providing an output, said output equals the absolute magnitude of said first frequency minus said second frequency, clock means for generating a variable rate clocking frequency, said clock means receiving said output from said frequency differencing means, said clock means generating a clock frequency in response to said frequency differencing means output, said clock frequency defining a time period, a bit select register for providing a plurality of digital bits, said bit select register receiving said high/low output from said frequency detector means, said bit select register receiving said clock frequency from said clock means, said bit select register generating a digital word in response to said clock frequency and said high/low output, and a D/A converter means receiving said digital word from said bit select register, said D/A converter means converting said digital word to an analog voltage, said D/A converter means providing said analog voltage as an output, said analog voltage tuning said microwave synthesizer to the desired frequency.