Single-VCO multi-band DTV frequency synthesizer with a divide-by-3 frequency divider for quadrature signal generation

摘要: A multi-band frequency synthesizer for In-phase and Quadrature (I/Q) LO signal generation in Digital TV tuners is presented. Using divisor numbers other than powers of 2 (2 n ) quadrature generation, reduces the required range VCO, hence number VCO circuits, synthesizers. In proposed synthesizer, VHF, UHF L-band frequencies are covered with only one VCO. This achieved by using a novel divide-by-3 circuit which produces precise I/Q signals. The tuning this design 2,400---3,632 MHz 6-bit switched-capacitor bank. fast adaptive calibration block selects closest to target setting coarse-tuning code prior start phase lock. programmable charge pump used reduce variations PLL characteristics over range. has been fabricated 0.18 μm CMOS technology die area 1.7 � 1.6 mm2. It consumes 27 mA from 1.8 V power supply. Measurement results show operation entire output noise VHF bands <�131dBc/Hz at 1.45 offset.