Abstract: A control circuitry (134) and a method for controlling a bi-directional switch (132) is provided. The bi-directional switch (132) having a control terminal (130) for receiving a control voltage (124) to control an on state and an off state of the bi-directional switch (132) and at least one semiconductor switch in a bi-directional main current path. The control circuitry (134) comprises an energy storage element (102), a coupling means (101) to couple the energy storage element (102) to a supply voltage to charge the energy storage element (102), and a control circuit (108) configured to receive power from the energy storage element (102) and configured to supply the control voltage having a voltage level being independent of the supply voltage when the energy storage element (102) is not coupled to the supply voltage. The coupling means (101) is configured for only coupling the 132 energy storage element (102) to the supply voltage when the bi-directional switch (132) is in the off state.

Abstract: Charge pump for providing an output current for charging and discharging a filter in accordance with an input signal, said charge pump comprising a first current source connectable with the input signal for driving the current source and adapted to providing a first current equal to a constant current Io plus a variable current ?x, said variable current ?x being directly proportional to the input signal, a second current source connectable with the input signal for driving the current source and adapted to providing a second current equal to the constant current Io minus said variable current ?x, and an output for providing the output current, wherein said output is connected to both the first and second current source in such a way, that the output current is equal to a difference between the first and second current.

Abstract: The present invention relates to Current mirror for generating a constant mirror ratio, comprising an output transistor (Tout) having a base, an emitter and a collector, wherein a current flowing through the collector of said output transistor (Tout) constitutes an output current (Iout) of said current mirror and the collector of said output transistor (Tout) is connectable to an output circuit, a buffer transistor having a base, an emitter and a collector, wherein the emitter of the buffer transistor is connected to the base of the output transistor, a buffer current source for providing a fixed buffer current, wherein said buffer current source is connected to the collector of the buffer transistor, and a buffer base voltage control means having an input connected to the base of the output transistor and an output connected to the base of the buffer transistor, wherein the base voltage control means is adapted to controlling a voltage at the base of the buffer transistor in response to a current at the inpu