| 摘要 |
A double conversion frequency converter includes first and second mixing stages. The first mixing stage includes a first programable Local Oscillator (LO) synthesizer and a first mixer, and the second mixing stage includes a second programable LO synthesizer and a second mixer. The first and second LO synthesizers have a wide band tuning range for receiving a separate predetermined reference signal and generating therefrom first and second LO output signals, respectively, which each are changeable by predetermined large frequency steps. The first mixer mixes an input signal to the frequency converter with the first LO output signal for generating a first predetermined mixer output signal. The second mixer mixes a predetermined sideband generated in the first predetermined mixer output signal with the second LO output signal for generating a second predetermined mixer output signal which is use for the output signal for the frequency converter. The predetermined output signal of the frequency converter is changed in small frequency steps (e.g., at least 1 KHz) by concurrently changing each of the first and second LO output signals using large frequency step changes (e.g., at least 125 KHz) whereby the difference between the large frequency steps in the first and second LO output signals is equal to the small frequency step of the predetermined output signal.
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