Abstract: The frequency synthesizer has two fixed frequency dividers, two charge pumps, five capacitors, a voltage controlled oscillator, and a transconductance voltage amplifier. The pulse widths of the input reference signal and the output signal are compared and the resultant signal is coupled to the oscillator to adjust its frequency. The circuit exhibits accurate frequency synthesizing, and thus can be used in wireless communication and signal processing systems. It provides a precise integer and fractional frequency division with a low phase noise. Moreover, it has a simple and compact structure that can be implemented in integrated circuit technologies such as CMOS.

Abstract: The frequency synthesizer has two fixed frequency dividers, two charge pumps, five capacitors, a voltage controlled oscillator, and a transconductance voltage amplifier. The pulse widths of the input reference signal and the output signal are compared and the resultant signal is coupled to the oscillator to adjust its frequency. The circuit exhibits accurate frequency synthesizing, and thus can be used in wireless communication and signal processing systems. It provides a precise integer and fractional frequency division with a low phase noise. Moreover, it has a simple and compact structure that can be implemented in integrated circuit technologies such as CMOS.

Abstract: The wideband programmable phase shifting circuitry includes a charge pump, a comparator, and a voltage reference generator block. An input signal controls the charge pump which charges and discharges a capacitor connected to an output of the charge pump. The comparator continuously compares the voltage across the capacitor with a reference voltage, ratio of VREF, which is generated by the voltage reference generator block. The voltage VREF is generated to compensate for power supply and integration process variations. The voltage reference generator is comprised of a charge pump unit, a frequency divider unit, switches, and two capacitors. The adjusted VREF ratio controls the comparator threshold level and hence a programmable phase difference between the input signal of the charge pump and the output signal of the comparator.

Abstract: The wideband programmable phase shifting circuitry includes a charge pump, a comparator, and a voltage reference generator block. An input signal controls the charge pump which charges and discharges a capacitor connected to an output of the charge pump. The comparator continuously compares the voltage across the capacitor with a reference voltage, ratio of VREF, which is generated by the voltage reference generator block. The voltage VREF is generated to compensate for power supply and integration process variations. The voltage reference generator is comprised of a charge pump unit, a frequency divider unit, switches, and two capacitors. The adjusted VREF ratio controls the comparator threshold level and hence a programmable phase difference between the input signal of the charge pump and the output signal of the comparator.