Analog switching circuit, associated control circuit and method

A control circuit for controlling an analog switch, the analog switch having a first terminal, a second terminal and a control terminal, and the analog switch comprising a NMOS and a PMOS coupled in parallel with the NMOS, wherein the control circuit has a first input electrically coupled to the first terminal, a second input electrically coupled to the control terminal, a first output electrically coupled to a backgate of the NMOS and a second output electrically coupled to a backgate of the PMOS, the control circuit comprising:

• a first control switch having a first end, a second end and a control end, wherein the first end is electrically coupled to the first terminal, the second end is electrically coupled to the backgate of the NMOS;
• a second control switch having a first end, a second end and a control end, wherein the first end of the second control switch is electrically coupled to the backqate of the NMOS, the second end of the second control switch is electrically coupled to a reference ground;
• and
• a second logic circuit having an input electrically coupled to the control terminal, a first output electrically coupled to the control end of the first control switch and a second output electrically coupled to the control end of the second control switch;
• wherein the first control switch and the second control switch comprise NMOS, and the second logic circuit comprises a first RS flip latch, wherein the first RS flip latch comprises:
• a SET input electrically coupled to the control terminal;
• a RESET input electrically coupled to the control terminal;
• a first output electrically coupled to the control end of the first control switch;
• and
• a second output electrically coupled to the control end of the second control switch;
• wherein
• when the SET input is enabled, the first control switch is turned ON and the second control switch is turned OFF, and when the RESET input is enabled, the first control switch is turned OFF and the second control switch is turned ON;
• wherein the second output electrically coupled to the backgate of the PMOS is an output of a circuit element that is distinct from the RS flip latch.

A method of controlling an analog switch, the analog switch receiving an input signal and a switching control signal and outputting an output signal based on the input signal and the switching control signal, the analog switch comprising an NMOS and a PMOS coupled in parallel, the method comprising:

• turning ON the NMOS and the PMOS when the switching control signal is in a first logic state, and controlling a backgate voltage of the NMOS and a backgate voltage of the PMOS to follow the input signal;
• and
• turning OFF the NMOS and coupling the backgate voltage of the NMOS to a ground voltage and turning OFF the PMOS and coupling the backgate voltage of the PMOS to a voltage source when the switching control signal is in a second logic state different from the first logic state;
• wherein controlling the backgate voltage of the NMOS comprises:
• adopting a first control switch to selectively couple the backgate of the NMOS to an input terminal of the analog switch;
• adopting a second control switch to selectively couple the backgate of the NMOS to a reference ground;
• coupling a control end of the first control switch to a first output of a RS flip latch, coupling a control end of the second control switch to a second output of the RS flip latch, wherein when the switching control signal is in a first logic state, a SET input of the RS flip latch is enabled, the first control switch is turned ON and the second control switch is turned OFF, and when the switching control signal is in a second logic state, a RESET of the RS flip latch is enabled, the first control switch is turned OFF and the second control switch is turned ON;
• wherein a circuit element distinct from the RS flip latch controls the backgate the backgate voltage of the PMOS.