| 摘要 |
<P>PROBLEM TO BE SOLVED: To obtain a quadrature modulator which achieves excellent modulation precision by ensuring isolation between two even-harmonic mixers while using a low-pass filter. <P>SOLUTION: A quadrature modulator comprises: an LO (local oscillator) 1; an amplifier 2 for amplifying an LO signal; a low-pass filter 3 for removing a high-frequency component from the LO signal; an in-phase distributor 4 for distributing an output signal of the low-pass filter 3; first and second even-harmonic mixers 5, 6; an I-channel baseband signal generating section 7 and a Q-channel baseband signal generating section 8; a 90° synthesizer 9; and a serial circuit constituted of a resistor 10 and a 1/4 wavelength line 11. The serial circuit is inserted between an output terminal of the low-pass filter 3 and a ground 12. <P>COPYRIGHT: (C)2009,JPO&INPIT |
