Back to results
US 5,166,629 AGranted
Direct frequency synthesizer
AssigneeWestinghouse Electric Corp.
InventorsGrant H. Watkins, John P. Muhlbaier
Life of this patent
Estimating the term…
Abstract
A direct frequency synthesizer is provided with a single stage or multiple cascaded stages. Each stage includes a fixed frequency input channel and a selectable frequency input channel which are coupled respectively to the I and L ports of a mixer. The input channel includes a divider having a divisor equal to N. The selectable frequencies range from f.sub.1 to f.sub.1 +j.theta.. Single-pole-multiple-throw switches selectively connect the fixed and selectable frequencies to the mixer to generate output frequency signals through an output filter bank. Specific relationships among N, n and .theta. are used to establish continuous output frequency coverage, stage cascadability and other synthesizer operating features.
Claims28
A direct frequency synthesizer comprising:
- means for generating a set of fixed frequency signals from F.sub.L to F.sub.H which define a frequency band B, the successive signals in said fixed frequency signal set being spaced from each other by a frequency increment D;
- means for dividing said fixed frequency signals by a divisor N;
- first filter means for passing said fixed frequency signals and rejecting undesired signals after division by said divider means and for rejecting undesired signals outside said band B;
- means for generating a set of selectable LO frequency signals from f.sub.1 to (f.sub.1 +j.theta.) with the successive signals in said selectable LO frequency signal set being spaced from each other by a frequency increment .theta.;
- means for mixing sad fixed frequency signals from the output of said first filter means and said selectable LO frequency signals to generate mixer product signals;
- first means for selectively coupling one of said fixed frequency signals and one of said selectable LO frequency signals to said mixing means for each selected synthesizer output frequency signal;
- output filter means coupled to the output of said mixing means and including a plurality of interconnected output filters for rejecting undesired signals and an output where the selected synthesizer output frequency is generated within a synthesizer output frequency band F.sub.1 through F.sub.i ;
- second means for selectively coupling the output of said mixing means through one or more of said output filters to said filter output in accordance with the selected output frequency;
- and
- said frequency signals F.sub.H and F.sub.L being valued to provide continuous output frequency coverage in accordance with a first predetermined relationship among the parameters N, n, and .theta. where n is equal to an integer one less than the number of LO frequencies in the frequency span associated with the touching of the highest edge of a mixing means sum band and the lowest edge of a mixing means difference band.
7 more elements
A direct frequency synthesizer comprising:
- A.) means for generating a set of fixed input frequency signals from F.sub.L to F.sub.H which define a frequency band B, the successive signals in said fixed frequency signal set being spaced from each other by a frequency increment D;
- and
- B.) a plurality (x) of cascaded stages, each of said stages having
- a. means for dividing said fixed input frequency signals by a divisor N;
- b. first filter means for passing said fixed input frequency signals and rejecting undesired signals after division by said divider means and for rejecting undesired signals outside said band B;
- c. means for generating a set of selectable LO frequency signals from f.sub.1 to (f.sub.1 +j.theta.) with the successive signals in said selectable LO frequency signal set being spaced from each other by a frequency increment .theta.;
- d. means for mixing said input frequency signals after filtered by said first filtered means and said selectable LO frequency signals to generate mixer product signals;
- e. first means for selectively coupling one of said input frequency signals and one of said selectable LO frequency signals to said mixing means for each selected synthesizer output frequency signal;
- f. output filter means coupled to the output of said mixing means for rejecting undesired signals and having a stage output;
- and
- C.) said generating means being coupled to the input of said dividing means of the first stage to apply said fixed frequency signals as said input frequency signals;
- D.) said stage output of each of said stages except the x stage being coupled to transmit input frequency signals to said dividing means of the next stage;
- E.) said output filter means for said x stage having a plurality of interconnected output filters for rejecting undesired signals and an output where the selected synthesizer output frequency is generated within a synthesizer output frequency band F.sub.1 through F.sub.i ;
- F.) second means for selectively coupling the output of said mixing means of said x stage through one or more of said x stage output filters to said x stage filter output in accordance with the selected output frequency;
- G.) said frequency signals F.sub.H and F.sub.L being valued to provide continuous output frequency coverage in accordance with a first predetermined relationship among the parameters N, n, and .theta. where n is equal to an integer one less than the number of LO frequencies in the frequency span associated with the touching of the highest edge of a mixing means sum band and the lowest edge of a mixing means difference band;
- and
- H.) said parameters N, n and .theta.r having a second predetermined relationship so that F.sub.L =F.sub.1 and F.sub.H =F.sub.i.
14 more elements
The direct frequency synthesizer of claim 22 wherein N=8 and n=6.
Dependencies are inferred from the claim text.