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System incorporating power supply rejection circuitry and related method

  • US 8,829,982 B2
  • Filed: 07/09/2012
  • Issued: 09/09/2014
  • Est. Priority Date: 07/28/2011
  • Status: Active Grant
First Claim
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1. An electronic system including:

  • a first subcircuitry;

    a second subcircuitry, anda phase locked loop (PLL),wherein the first subcircuitry positioned to provide a supply voltage, VDD, as a filtered version of power, PV, available from an external power source, to the second subcircuitry, wherein the first subcircuitry is separate from the second subcircuitry,wherein the first subcircuitry comprises;

    a first transistor having first and second source/drain regions and a gate region; and

    a first low pass filter coupled to receive a power source signal from the external power source during operation of the second subcircuitry,wherein the first low pass filter is also coupled to provide a filtered version of the power source signal to the gate region of the first transistor, so that when the first source/drain region of the first transistor is coupled to receive power from the external power source and the gate region of the first transistor receives the filtered version of the power source signal, the second source/drain region of the first transistor provides a first modified version of the power, PV, received from the external power source,wherein the second subcircuitry includes;

    a second transistor directly coupled in series with the first transistor,wherein the first and second transistors are of a same conductivity type, wherein the second transistor has first and second source/drain regions and a gate region, wherein the first source/drain region of the second transistor is coupled to the first transistor, and wherein the second source/drain region of the second transistor is coupled to a power node of the PLL;

    wherein the first source/drain region of the second transistor is coupled to receive the first modified version of the power, Pv, received from the external power source;

    wherein the electronic system further comprises;

    a first resistor; and

    a second low pass filter coupled in series with the first resistor to receive a signal from the external power source during operation of the second subcircuitry, wherein the second low pass filter is coupled to provide a second filtered version of the power source signal to the gate region of the second transistor, so that when the first source/drain region of the first transistor receives power, Pv, from the external power source and the second low pass filter provides the second filtered version of the power source signal to the gate region of the second transistor, the second source/drain region of the second transistor provides a second modified version of the power, PV, in accord with application of the second filtered version of the power source signal to the gate region of the second transistor.

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