| 摘要 |
PURPOSE:To obtain a stable, small-size, and high-reliability receiver of less distortion and high selectivity, by using a filter constituted by combining switches, capacitors, and operational amplifiers, namely, a switched capacitor filter. CONSTITUTION:An antenna input is inptted to the band pass filter of a switched capacitor filter SCF1 after amplification. The pass band of the SCF1 is determined by a clock CL1 obtained by dividing the frequency of an OSC in a PC2 in accordance with the determined code of the receiving station from a control part CONT and a decoder DEC. The output signal of the SCF1 is mixed down with the local frequency generated by the PLL loop (VCO PC1 PD LPF) and is amplified by an intermediate frequency amplifier IF. This intermediate frequency signal has signal band components taken out by a band pass SCF2 whose pass band is determined unequivocally by a clock CL2 divided by a frequency divider DIV, and they are detected by a detector DET. |
