Amplifier circuit using voltage-to-current conversion and associated envelope tracking supply modulator using the same

An amplifier circuit comprising:

• a voltage-to-current conversion circuit, arranged to generate a current signal according to an input voltage signal, wherein the voltage-to-current conversion circuit comprises:
• an operational transconductance amplifier (OTA), arranged to output the current signal at an output port of the OTA;
• and
• a current-to-voltage conversion circuit, arranged to generate an output voltage signal according to the current signal, wherein the current-to-voltage conversion circuit comprises:
• a linear amplifier (LA), wherein an input port of the LA is coupled to the output port of the OTA, and the output voltage signal is derived from an output signal at an output port of the LA;
• wherein the output voltage signal is generated at an output port of the current-to-voltage conversion circuit, and the output port of the current-to-voltage conversion circuit is coupled to a switching converter via an inductor.

An envelope tracking supply modulator comprising:

• an amplifier circuit, arranged to receive an envelope input, and generate an amplifier output according to the envelope input, wherein the amplifier output is involved in setting a modulated supply voltage of a power amplifier, and the amplifier circuit comprises:
• a voltage-to-current conversion circuit, arranged to generate a current signal according to the envelope input, wherein the voltage-to-current conversion circuit comprises:
• an operational transconductance amplifier (OTA), arranged to output the current signal at an output port of the OTA;
• and
• a current-to-voltage conversion circuit, arranged to generate the amplifier output according to the current signal, wherein the current-to-voltage conversion circuit comprises:
• a linear amplifier (LA), wherein an input port of the LA is coupled to the output port of the OTA, an output port of the LA is coupled to the PA, and the amplifier output is derived from an output signal at the output port of the LA;
• wherein the OTA is a source degenerated amplifier, and the source degenerated amplifier comprises a differential pair with source degeneration, and further comprises amplifiers arranged to boost transconductance of the differential pair.

An envelope tracking supply modulator comprising:

• an amplifier circuit, arranged to receive an envelope input, and generate an amplifier output according to the envelope input, wherein the amplifier output is involved in setting a modulated supply voltage of a power amplifier, and the amplifier circuit comprises:
• a voltage-to-current conversion circuit, arranged to generate a current signal according to the envelope input, wherein the voltage-to-current conversion circuit comprises:
• an operational transconductance amplifier (OTA), arranged to output the current signal at an output port of the OTA;
• and
• a current-to-voltage conversion circuit, arranged to generate the amplifier output according to the current signal, wherein the current-to-voltage conversion circuit comprises:
• a linear amplifier (LA), wherein an input port of the LA is coupled to the output port of the OTA, an output port of the LA is coupled to the PA, and the amplifier output is derived from an output signal at the output port of the LA;
• and
• a switching converter;
• wherein the amplifier output is generated at an output port of the current-to-voltage conversion circuit, and the output port of the current-to-voltage conversion circuit is coupled to the switching converter via an inductor.