Abstract: A device in a phase-locked loop circuit that dynamically matches the currents in a charge pump to reduce the spurious tones during each charge pump event when the phase-locked loop is in lock. A regulator circuit is coupled to a first current source in a charge pump and is responsive to inverted up and down signals from a phase detector or to the currents of a charge pump. The integrator may adjust the first current to equal the second current when inverted up and down signals do not arrive at the regulator at the same time or when the loop filter voltage does not match the charge pump output voltage with both current sources of the charge pump are turned on but disconnected from the loop filter.

Abstract: A modulation synthesizer circuit produces a fixed intermediate frequency unmodulated signal without harmonics aliasing back into the transmit spectrum, thus, eliminating the need for a bandpass filter. The modulation synthesizer circuit includes a phase shifter placed before the down conversion mixer. The phase shifter may be placed outside the modulation synthesizer loop such that the phase shifter produces quadrature carrier wave signals to the down conversion mixer. In the alternative the phase shifter may be kept within the modulation synthesizer loop and produce quadrature modulated transmit signals to the down conversion mixer. Any harmonic frequencies generated by the phase shifter are harmonics of the carrier wave signal or modulated transmit signal. Thus, with the appropriate choice of carrier wave signal or modulated transmit signal, any harmonics generated by the phase shifter can be prevented from aliasing back into the transmit spectrum and therefore need not be filtered.

Abstract: An apparatus for reducing the power consumed by, and the noise generated at the output of a charge pump which is part of a phase locked loop circuit. A reduction in the power consumed by the charge pump is achieved by synchronizing the powering up of the charge pump bias circuit to the state of the counters which control the timing of the signal which triggers a charge pump cycle. In this way current is supplied to the charge pump circuit only when needed for the operation of the pump. A reduction in the noise present at the output of the charge pump caused by the reloading of the counters while the pump is activated is achieved by loading a portion of the counter bits prior to activating the pump. A circuit detects when the counter is close to a value of zero and produces a signal which loads the most significant bits of the counter. When the counter reaches a value of zero, the remaining bits are loaded.