Output stage for a low-current charge pump and demodulator integrating such a pump

Claim 2

A charge pump device comprising: an output terminal; a current mirror; a capacitive element located between said current mirror and said output terminal; and a switch which selectively provides a series connection of said current mirror and said capacitive element to said output terminal.

Claim 3

The charge pump device of claim 1, wherein said switch provides said series connection in response to an input signal of said charge pump device.

Claim 4

The charge pump device of claim 1, wherein said capacitive element is formed by a transistor having a bias terminal receiving a bias signal which is in-phase with a switching signal received by said switch.

Claim 5

The charge pump device of claim 1, further comprising another capacitive element formed by a transistor having a bias terminal receiving a bias signal which is out-of-phase with a switching signal received by said switch.

Claim 6

The charge pump device of claim 1, wherein said current mirror is connected between said output terminal and a first supply terminal, said charge pump device further comprising: another current mirror connected between said output terminal and a second supply terminal; another capacitive element located between said another current mirror and said output terminal; and another switch which selectively connects in series said another current mirror and said another capacitive element to said output terminal.

Claim 7

A phase-locked loop demodulator which outputs a demodulated signal comprising: a phase detector which detects a phase difference between two input signals and outputs a control signal; a charge pump which receives said control signal and outputs said demodulated signal; and an oscillator which receives said demodulated signal and provides one of said two input signals; wherein said charge pump comprises: an output terminal; a current mirror; a capacitive element located between said current mirror and said output terminal; and a switch which selectively provides a series connection of said current mirror and said capacitive element to said output terminal in response to said control signal.

Claim 8

A phase-locked loop demodulator which outputs a demodulated signal comprising: a phase detector which detects a phase difference between two input signals and outputs a control signal; a charge pump which receives said control signal and outputs said demodulated signal; and an oscillator which receives said demodulated signal and provides one of said two input signals; wherein said charge pump comprises: an output terminal; a current mirror; a capacitive element located between said current mirror and said output terminal; and a switch which selectively provides a series connection of said current mirror and said capacitive element to said output terminal in response to said control signal.

Claim 9

A radio telephone comprising: an antenna which receives a radio signal; a mixer which changes a frequency of said radio signal to an intermediate frequency and outputs an intermediate frequency signal; and a demodulator which demodulates said intermediate frequency signal and outputs a demodulated signal, said demodulator comprising: a phase detector which detects a phase difference between two input signals and outputs a control signal; a charge pump which receives said control signal and outputs said demodulated signal; and an oscillator which receives said demodulated signal and provides one of said two input signals; wherein said charge pump comprises: an output terminal; a current mirror; a capacitive element located between said current mirror and said output terminal; and a switch which selectively provides a series connection of said current mirror and said capacitive element to said output terminal in response to said control signal.

Claim 10

A radio telephone comprising: an antenna which receives a radio signal; a mixer which changes a frequency of said radio signal to an intermediate frequency and outputs an intermediate frequency signal; and a demodulator which demodulates said intermediate frequency signal and outputs a demodulated signal, said demodulator comprising: a phase detector which detects a phase difference between two input signals and outputs a control signal; a charge pump which receives said control signal and outputs said demodulated signal; and an oscillator which receives said demodulated signal and provides one of said two input signals; wherein said charge pump comprises: an output terminal; a current mirror; a capacitive element located between said current mirror and said output terminal; and a switch which selectively provides a series connection of said current mirror and said capacitive element to said output terminal in response to said control signal.