Charge pump circuits for PLL frequency synthesizer

Details Charge pump circuits for PLL frequency synthesizer Charge pump circuits for PLL frequency synthesizer

1994-08-11

1996-07-09

Grimm, Siegfried H.

Oscillators

Automatic frequency stabilization using a phase or frequency...

Transistorized controls

331 14, 331 17, 331 25, 327157, H03L 7093

Patent

active

055348211

ABSTRACT:
A PLL frequency synthesizer, which comprises a voltage controlled oscillator, and a comparison frequency divider for dividing a frequency of the output signal from the voltage controlled oscillator to output a comparison signal. A phase comparator in the synthesizer compares a phase of a reference signal to be fed thereto with a phase of the comparison signal, and generates first and second phase difference signals, based on the compared result. The synthesizer further includes a charge-pump circuit operated based on the first and second phase difference signals, and having an output terminal connected to the voltage controlled oscillator. The charge-pump circuit includes a first bipolar transistor connected between a high-potential power supply and the output terminal, and a second bipolar transistor connected between a low-potential power supply and the output terminal. The first and second bipolar transistors are controlled based on the first and second phase difference signals, respectively. At least one of the first and second bipolar transistors is an emitter-follower type. In another embodiment, a node is provided between two switches formed by CMOS transistors, to serve as an output terminal of the charge-pump circuit. In a further embodiment, two PMOS transistors are provided as switches, and a node is provided therebetween to serve as an output terminal of the charge-pump circuit.

REFERENCES:
patent: 3009070 (1961-11-01), Barnes
patent: 4792705 (1988-12-01), Ouyang et al.
patent: 4926141 (1990-05-01), Herold et al.
patent: 4970472 (1990-11-01), Kennedy et al.
patent: 5003198 (1991-03-01), Bell
patent: 5124594 (1992-06-01), Numata et al.

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