Patent ID: 6282252
Filing Date: 2001-08-28
Classification: H03D,H03G

Abstract:
A receiver suitable for data transmission, comprising:a mixer for frequency-converting a received signal to an intermediate frequency signal;a local oscillator for inputting local oscillation signals to said mixer;a demodulator for demodulating the intermediate frequency signal to detect baseband signals;a variable attenuator provided between said mixer and said demodulator, said variable attenuator having a PIN diode so as to hold constant the level of the intermediate frequency signal inputted to said demodulator; andimpedance matching circuitry provided between said mixer and said variable attenuator, said impedance matching circuitry having a circuit consisting of a capacitor, an inductor, and a resistor connected in parallel to each other so as to match an output impedance of said mixer to said variable attenuator; wherein:said mixer is formed of a dual-gate MOS FET;said received signal is input into a first gate of said dual-gate MOS FET, and the local oscillation signals from said local oscillator are input into a second gate of said dual-gate MOS FET;an input terminal of said impedance matching circuitry is connected to a drain of said dual-gate MOS FET; anda band elimination filter for attenuating a frequency band of the local oscillation signals is disposed between an output terminal of said impedance matching circuitry and an input terminal of said variable attenuator.