US 12,261,597 B2
Capacitor charging method, corresponding circuit and device
Alberto Marzo, Giarret (IT); Vincenzo Randazzo, Biancavilla (IT); Vanni Poletto, Milan (IT); and Giovanni Susinna, Catania (IT)
Assigned to STMicroelectronics S.r.l., Agrate Brianza (IT)
Filed by STMicroelectronics S.r.l., Agrate Brianza (IT)
Filed on May 22, 2023, as Appl. No. 18/321,568.
Claims priority of application No. 102022000012617 (IT), filed on Jun. 14, 2022.
Prior Publication US 2023/0403005 A1, Dec. 14, 2023
Int. Cl. H03K 17/687 (2006.01); H03K 17/0412 (2006.01); H03K 17/06 (2006.01)
CPC H03K 17/687 (2013.01) [H03K 17/04123 (2013.01); H03K 17/063 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A method for controllably transferring electrical charge from a supply voltage to a capacitive load, the method comprising:
coupling the capacitive load to the supply voltage through a drain to source current flow path of a transistor;
charging, by a drive circuit, the capacitive load by making the transistor selectively conductive in response to a gate-source voltage of the transistor exceeding a threshold voltage, wherein a difference between the gate-source voltage and the threshold voltage provides an overdrive value;
a ramp generator circuit configured to generate a controlled ramp signal;
driving, by the drive circuit, a gate terminal of the transistor with the controlled ramp signal such that the overdrive value is constant, the controlled ramp signal being a variable gate-source voltage; and
providing, by a level shifter circuit, a level-shifted replica of the controlled ramp signal, the level shifter circuit arranged in a cascaded arrangement with the ramp generator circuit.