| 摘要 |
<p>An improved mixed down synthesizer scheme (10) having a first phase locked loop (12) and a second phase locked loop (14) provides a first frequency and a second frequency respectively. The first phase locked loop (12) has at least a first programmably tunable filter (30) and a mixer (28). The second phase locked loop (14) has an output received by the mixer (28) in the first phase locked loop (12). A controlling means (18 and 20) controls the first and second frequencies and tunes the first programmably tunable filter (30). The first and second phase locked loops (12) and (14) are programmed to maintain a constant frequency ratio between the first and second frequencies in order to maintain a minimum frequency offset from the mixed-in spurious products.</p> |
