Abstract: A filter circuit includes a phase inversion branching circuit branching an input signal and outputting separately first and second signals with mutually-inverted phases from first and second output terminals; a first band rejection filter connected the first output terminal of the phase inversion branching circuit and having a first rejection band; a second band rejection filter connected to the second output terminal of the phase inversion branching circuit and having a second rejection band different from the first rejection band; and a combiner combining the outputs of the first and second band rejection filters.

Abstract: A voltage controlled oscillator includes: a voltage controlled oscillation circuit, an oscillation frequency thereof being controlled by a control voltage signal; a PLL circuit that generates a control voltage signal to be input to the voltage controlled oscillation circuit; a multiplier circuit that multiplies an oscillation signal output from the voltage controlled oscillation circuit; and a band-pass filter and trap circuit that sets a pass band for passing a signal with a predetermined multiplication number of multiplication signals output from the multiplier circuit and a trap frequency equal to the frequency of the oscillation signal input to the multiplier circuit, and varies the pass band and the trap frequency in synchronization with the control voltage signal.

Abstract: An electronic circuit board includes a first insulating base layer, a ground conductor provided on a lower surface of the first insulating base layer, an insulating thin film layer laminated and fixed on the first insulating base layer, a pair of microstrip lines, the microstrip lines being provided on an upper surface and a lower surface of the insulating thin film layer, a second insulating base layer laminated and fixed on the insulating thin film layer, a conductor pattern provided on an upper surface of the second insulating base layer, and electronic components mounted on the conductor pattern. Opposite surfaces of the microstrip lines are roughened, such that an electrical potential difference between the roughened surfaces of the microstrip lines is suppressed. Further, surfaces of the microstrip lines opposite to the roughened surfaces are substantially planarized.

Abstract: The object of this invention is an oscillation circuit that increases the Q of the parallel resonance circuit and increases the C/N (carrier-to-noise) ratio. The oscillation circuit contains two feedback capacitors connected between the base and emitter and between the emitter and collector of a transistor. Two inductors are also connected in series between the base and the collector of the transistor. One end of a resistor is connected to the emitter of the transistor and the other end is connected between the two inductors. The feedback capacitors and inductors constitute a parallel resonance circuit that may be tuned to create an equipotential across the ends of the resistor so that no current flows through it thus increasing both Q and the C/N ratio.