Power noise filter and supply modulator including the same

A power noise filter comprising:

• a band stop filter;
• a low pass filter;
• a second inductor;
• wherein,
• the band stop filter includes a first inductor and a first capacitor, which are connected in parallel between first and second nodes,
• the first node receives a first voltage, which is filtered by the band stop filter to thereby generate a second voltage at the second node,
• the low pass filter includes:
• the first inductor and a second capacitor, which has one end connected to a third node and an opposite end connected to a ground source;
• and
• a resistor connected between the second node and the third node, wherein a filtered supply voltage is output at the third node from the power noise filter,
• wherein the second inductor is connected between the first and third nodes.

A supply modulator comprising:

• a direct current-to-direct current (DC-to-DC) converter configured to receive an envelope tracking signal and to generate a maximum voltage corresponding to a maximum level of the envelope tracking signal;
• a linear voltage generator configured to linearly convert and distribute the maximum voltage;
• a level selector configured to generate an output voltage that fits the envelope tracking signal;
• and a power noise filter configured to generate a supply voltage by reducing or eliminating power noise in the output voltage, wherein the power noise filter includes a band stop filter and a low pass filter, the band stop filter includes an inductor and a first capacitor, which are connected in parallel between first and second nodes, the first node receives the output voltage from the level selector, a filtered voltage is provided at the second node, and the low pass filter includes the inductor and a second capacitor, wherein the second capacitor has:
• (i) one end directly connected to the second node or directly connected to a first end of a resistor and a third node, wherein a second end of the resistor is directly connected to the second node, and (ii) an opposite end connected to a ground source.

A wireless communication device comprising:

• a modem configured to generate an envelope tracking signal and a transmission signal;
• a radio frequency integrated circuit (RFIC) configured to generate a radio frequency (RF) signal by modulating a carrier wave with the transmission signal;
• a power amplifier configured to amplify the RF signal;
• and
• a supply modulator configured to receive the envelope tracking signal and output a supply voltage to the power amplifier,
• wherein
• the supply modulator includes a direct current-to-direct current (DC-to-DC) converter, which receives the envelope tracking signal and generates a maximum voltage corresponding to a maximum level of the envelope tracking signal, a linear voltage generator, which linearly converts and distributes the maximum voltage, a level selector, which generates an output voltage that fits the envelope tracking signal, and a power noise filter, which generates a supply voltage by reducing or eliminating power noise in the output voltage, and
• the power noise filter includes a band stop filter and a low pass filter,
• the band stop filter includes an inductor and a first capacitor, which are connected in parallel between first and second nodes,
• the first node receives the output voltage from the level selector,
• a filtered version of the output voltage is provided at the second node, and
• the low pass filter includes the inductor and a second capacitor, wherein the second capacitor has:
• (i) one end directly connected to the second node or directly connected to a first end of a resistor and a third node, wherein a second end of the resistor is directly connected to the second node, and (ii) an opposite end of the second capacitor is connected to a ground source.