Controlled current source for accelerated switching

A charge pump comprising:

• two control inputs for receiving control signals, an output intended to supply an output current whose direction and value depend on the values of the control signals,
• a first and a second controlled current source, each controlled current source including
• a plurality of parallel-arranged power transistors each having a reference terminal, a transfer terminal and a bias terminal, the transfer terminals of the power transistors being jointly connected to the output of the current source, and
• a control module having an input coupled to one of said charge pump inputs for receiving the control signal, and an output intended to supply a signal enabling the power transistors to be turned on, wherein the reference terminals of the power transistors are jointly connected to the output of the control module, said output being intended to supply a current whose value depends on the value of the control signal, the bias terminals of the power transistors being permanently subjected in the operative state of the current source to a voltage of a predetermined value enabling said power transistors to be rendered potentially conducting;
• the outputs of the first and second current sources being connected to the first and the second branch of a current mirror, the output of one of the current sources being also connected to the output of the charge pump.

An apparatus for receiving radioelectric signals, comprising an antenna and filtering system allowing reception of a signal whose frequency is selected within a given range of frequencies, and its transformation into an electronic signal referred to as radio signal, in which apparatus a frequency conversion from the selected frequency to a predetermined intermediate frequency is performed by means of a mixer intended to receive the radio signal, on the one hand, and an output signal of a local oscillator whose frequency is determined by the value of a tuning voltage, on the other hand, said apparatus also comprising a phase/frequency detector intended to compare the frequency of the output signal of the oscillator with that of a reference signal and to supply, to a charge pump, the charge pump including two control inputs intended to receive control signals, an output intended to supply an output current whose direction and value depend on the values of the control signals, a first and a second controlled current source, each controlled current source having a plurality of parallel-arranged power transistors each having a reference terminal, a transfer terminal and a bias terminal, the transfer terminals of the power transistors being jointly connected to the output of the current source, and a control module having an input coupled to one of said charge pump inputs for receiving the control signal, and an output intended to supply a signal enabling the power transistors to be turned on, wherein the reference terminals of the power transistors are jointly connected to the output of the control module;

• said output being intended to supply a current whose value depends on the value of the control signal, the bias terminals of the power transistors being permanently subjected in the operative state of the current source to a voltage of a predetermined value enabling said power transistors to be rendered potentially conducting, the outputs of the first and second current sources being connected to the first and the second branch of a current mirror, the output of one of the current sources being also connected to the output of the charge pump, control signals whose values depend on the result of said comparison, the output of the charge pump being connected to a capacitor intended to generate the tuning voltage at its terminals.