Circuit for a medical device or for another device, medical device and method

Circuit (100) according to any one of the preceding claims, wherein the adjusting unit (160) is configured to adjust the control signal (302, PWM) to increase the supply voltage (HV) when the predicted change indicates that the output signal (V_PAT) will increase or the amplitude of the output signal (V_PAT) will increase, and

• wherein the adjusting unit (160) is configured to adjust the control signal (302, PWM) to decrease the supply voltage (HV) when the predicted change indicates that the output signal (V_PAT) or the amplitude of the output signal (V_PAT) will decrease, and/or
• wherein the prediction unit is configured to predict the change based on an alternating electrical signal comprising a varying amplitude, wherein preferably a frequency of the variation of the amplitude is lower than a frequency of the variation of the alternating signal itself, e.g. lower than 50 percent of the frequency of the alternating signal or lower than 10 percent of the frequency of the alternating signal.

Circuit (100) according to any one of the preceding claims, wherein the prediction unit (160) is configured to consider an implicit model and/or a heuristic model and/or a theoretical model of the change of the impedance (Z) of a load (140) at an output of the signal source (TCA, 400) for the prediction of the change, preferably a heuristic model or theoretical model of a load (140) which is formed by the tissue of a person.

Circuit (100) according to any one of the preceding claims, comprising a current control unit (500b) for controlling the current at the output of the signal source (TCA, 400) according to an electrical signal (REQ_CURRENT) which corresponds to a reference current, e.g. according to an alternating reference current or according to an alternating reference current having a varying amplitude or according to a constant reference current.

Circuit (100) according to any one of the preceding claims, comprising a signal conditioning unit (U1A) which is configured to transform two input signals, preferably two input voltage signals (DAC_OUT1, DAC_OUT2), to a single output signal preferably without offset, preferably to a single output voltage signal (REQ_CURRENT), wherein the single output signal corresponds to a reference current.

Circuit (100) according to any one of the preceding claims, wherein the voltage converter (110, 300) comprises:

• a switching transistor (T301), preferably a MOSFET,
• an inductor (L1), preferably one terminal of the conductor (L1) connected to or connectable to a power source (302) and the other terminal of the inductor (L1) connected to a first circuit node (N301) which is connected with a first doped area (D) of the switching transistor (T301), a first diode, preferably the anode of the first diode (D1) connected to the first circuit node (N301) and the cathode of the first diode (D1) connected to a positive power rail (+HV), and
• a first capacitor (C301), preferably one electrode of the first capacitor (C301) connected to the cathode of the first diode (D1).

Circuit (100) according to any one of the preceding claims, wherein the signal source (TCA, 400) comprises:

• a bias generating unit (BG),
• a first amplifier stage (AMP1), preferably at least one input of the first amplifier stage (AMP1) connected to at least one output of the bias generating unit (BG), and
• a second amplifier stage (AMP2), preferably at least one input of the second amplifier stage (AMP2) connected to at least one output of the first amplifier stage (AMP1), preferably via at least one current mirror unit (CM1, CM2).

Circuit (100) according any one of the preceding claims, wherein the signal source (TCA, 400) comprises two input nodes (INPUT1, INPUT2) which are connected directly with a differential input signal (DAC_OUT1, DAC_OUT2), or

• wherein the signal source (TCA, 400) comprises a first input node (INPUT1) and a second input node (INPUT2) which are connected to different input signals respectively, preferably a non-inverting input node (INPUT1) that is connected to a signal which corresponds to a required or desired output current (REQ_CURRENT) of the signal source (TCA, 400) and preferably an inverting input node (INPUT2) that is connected to an error signal (CURRENT_FEEDBACK) which represents the difference between a signal corresponding to a measured current (I_PAT) and a signal (REQ_CURRENT) corresponding to a reference current (I_AMP),
• wherein the reference current (I_AMP) is preferably equal to the required output current (I_AMP) of the signal source (TCA, 400).

Medical device, especially brain stimulation device (D), comprising a circuit (100) according to one of the preceding claims, and

• preferably at least one electrode (E1, E2), and
• preferably a supporting structure for arranging the at least one electrode (E1, E2) on the head of a person, especially on the head of a person which is trained non-therapeutically by the brain stimulation device (D) or on the head of a patient which is treated therapeutically by the brain stimulation device (D).