US 5,764,087 A · Direct digital to analog microwave frequency signal simulator

Abstract

A direct digital-to-analog microwave frequency signal synthesizer device which employs both wideband and narrowband direct digital frequency synthesizer (DDFS) circuitry to improve frequency and phase agility, reduce spurious performance, and minimize direct analog circuitry. A clock output having an extremely precise and highly stabilized frequency is fed to the wideband DDFS circuit and to the narrowband DDFS circuit. One or the other is selectively enabled by control logic circuitry. When the former is enabled, precision, high frequency resolution, low spurious, fast frequency switching is achieved at the microwave output. When the latter is enabled, precision, high frequency and phase resolution, low spurious, is achieved, providing frequency chirp, and frequency phase control at the microwave output. The output of the wideband DDFS circuit is processed to reduce the spurious response and up-converted, while the output of the narrow band DDFS circuit is directly up-converted. The selected DDFS circuit, is frequency up-converted to provide a synthesized microwave output signal.

Claims6

Dependent claims

An apparatus for direct digital-to-analog microwave for narrowband and wideband suppressed spurious frequency signal synthesis, comprising:

an oscillator for generating a fixed frequency output selected from a range of discrete frequencies;
a reference frequency generator connected to said oscillator for stabilizing the fixed frequency output;
a clock generator connected to said reference frequency generator for producing a clock output with a precise frequency governed by the reference frequency generator;
a wideband direct digital frequency synthesizer (DDFS) circuit connected to said clock generator for providing fast frequency switching output;
a narrowband DDFS circuit connected to said clock generator for providing a frequency chirp, phase controlled output;
a control logic circuit connected to both the wideband DDFS circuit and narrowband DDFS circuit to selectively enable the wideband DDFS circuit and narrowband DDFS circuit and thereby select from a pair of DDFS frequency outputs output respectively from said narrowband DDFS circuit and said wideband DDFS circuit;
a DDFS spurious reduction circuit connected to said wideband DDFS circuit for reducing spurious response of said frequency output;
and
a microwave frequency converter circuit for expanding the frequency band and up-converting one of said selected DDFS frequency outputs to provide a synthesized microwave output signal therefrom.

6 more elements

Dependencies are inferred from the claim text.

Direct digital to analog microwave frequency signal simulator

Life of this patent

Direct digital to analog microwave frequency signal simulator

Life of this patent

Abstract

Claims6