Bidirectional analog multiplexer
AssigneeSTMicroelectronics (Grenoble 2) SAS
InventorsThierry Masson, Pawel Fiedorow
Life of this patent
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Abstract
An analog multiplexer includes inputs and one output. A switching circuit is coupled between each input and the output. Each switching circuit includes an NMOS switching module, having an on state and an off state, and a control module supplied by a first supply voltage and operating to reduce leakage currents of the NMOS switching module when in the off state. The control module further operates to make the first NMOS switching module bidirectional irrespective of voltages present at the input and at the output.
Claims28
A bidirectional switching circuit coupled between an input and an output, wherein the bidirectional switching circuit comprises:
- a transistor switch circuit controllable in an on state and an off state, and
- a control circuit coupled to the input and to the output and that receives a supply voltage and is configured to reduce leakage currents of the transistor switch circuit when in the off state, and further configured to make the transistor switch circuit operate in a bidirectional manner irrespective of voltages present at the corresponding input and output by applying a gate voltage for controlling the transistor switch circuit in the on state, said gate voltage being equal to a sum of a highest of the voltages present at the input and at the output and a threshold voltage of a diode and less than the supply voltage.
A bidirectional switching circuit coupled between an input and an output, wherein the bidirectional switching circuit comprises:
- a transistor switch circuit controllable in an on state and an off state;
- a control circuit configured to receive a supply voltage and operate to reduce the leakage currents of the transistor switch circuit when in the off state, and
- at least one voltage selection circuit configured to deliver the supply voltage that is at least greater than a highest of the voltages present at the input and at the output.
A bidirectional switching circuit, comprising:
- two extended-drain MOS transistors connected in series between an input and an output, wherein sources and substrates of the two extended-drain MOS transistors are mutually connected;
- and
- a control circuit comprising:
- a drive circuit operating responsive to a first logic state of a drive signal to selectively drive the gates, sources and substrates of the two extended-drain MOS transistors to ground;
- and
- an input circuit coupled to receive an input voltage at the input and an output voltage at the output, said input circuit configured to apply a gate voltage to the gates of the two extended-drain MOS transistors when the drive signal is in the second logic state, wherein the gate voltage is:
- equal to the input voltage plus an offset voltage if the input voltage exceeds the output voltage;
- and
- equal to the output voltage plus an offset voltage if the output voltage exceeds the input voltage.
A bidirectional switching circuit coupled between an input and an output, wherein the bidirectional switching circuit comprises:
- a transistor switch circuit controllable in an on state and an off state, and
- a control circuit that receives a supply voltage and is configured to reduce leakage currents of the transistor switch circuit when in the off state, and further configured to make the transistor switch circuit operate in a bidirectional manner irrespective of voltages present at the corresponding input and output;
- wherein the control circuit is further configured, when the supply voltage is zero, to turn off the transistor switch circuit resulting in current consumption at the input and at the output that is less than a threshold of the order of 0.1% of a normal current consumption in the presence of a nonzero supply voltage.
Dependencies are inferred from the claim text.