A voltage controlled oscillation device includes a voltage controlled oscillator, fixed-frequency oscillator, frequency mixer, and frequency selector. The voltage controlled oscillator changes the output signal frequency in the microwave band in accordance with the input voltage of a frequency control signal. The fixed-frequency oscillator has a fixed oscillation frequency higher than that of the voltage controlled oscillator. The frequency mixer mixes the output signal from the fixed-frequency oscillator and the output signal from the voltage controlled oscillator and outputs the sum frequency and difference frequency between the two signals. The frequency selector selects and outputs one of the sum frequency and difference frequency contained in the output signal from the frequency mixer.
Devices (1) for exchanging ultra wide band signals comprise frequency translating stages (20,30) for frequency translating signals and oscillating stages (40) for supplying main inphase/quadrature oscillation signals to the frequency translating stages (20,30). By providing the oscillating stages (40) with polyphase filters (43,44) for reducing harmonics in oscillation signals, the main oscillation signals will be sufficiently clean. The oscillating stages (40) comprise mixers (46) for converting first inphase/quadrature oscillation signals and second inphase/quadrature oscillation signals into the main oscillation signals. The polyphase filters (43,44) may be located before and after the mixers (46). Frequency selectors (45) replace prior art multiplexers located after the mixers (46). Such frequency selectors (45) comprise multiplexers (126,127) for supplying the second inphase/quadrature oscillation signals, with a combination of these second oscillation signals corresponding with a positive frequency, a negative frequency or a zero frequency, and comprise coders (125) for controlling the multiplexers (126,127).
A broadband receiver exhibiting reduced interference to a frequency counter caused by a local oscillator. The broadband receiver is arranged for detecting a radio signal of strong reception intensity and receiving the radio signal, and in a specific configuration includes: a reception system including an antenna for receiving the radio signal, a local oscillator for outputting a local oscillation signal, a frequency mixer for converting the radio signal to an intermediate frequency, and a demodulator for demodulating the intermediate frequency; a frequency counter for measuring the frequency of a radio signal having strong reception intensity; a control section for controlling the oscillation frequency of the local oscillator in such a manner that the radio signal having a strong reception intensity is demodulated by the reception system; and a local oscillator halting section for halting the oscillation of the local oscillator during the measurement of the frequency of the radio signal by the frequency counter.
