Single amplifier filter for constant group delay in radio frequency transmitters

A radio frequency transmitter comprising:

• a digital-to-analog conversion module configured to generate an input signal based on a baseband signal;
• a first filter having a cutoff frequency, wherein the first filter is configured to generate a first signal by attenuating frequency components of a second signal above the cutoff frequency;
• a second filter coupled between the first filter and the digital-to-analog conversion module, the second filter having only one amplifier, wherein the second filter is configured to generate the second signal based on the input signal by compensating for a phase response of the first filter such that a group delay of the first signal relative to the input signal is substantially constant for frequencies less than the cutoff frequency;
• and
• a modulation module coupled to the first filter, the modulation module being configured to generate an output signal by modulating the first signal using a carrier signal, wherein the second filter comprises:
• a first input node for the input signal;
• a first output node for the second signal;
• a first node;
• a second node for an inverse of the second signal;
• an amplifier having a first amplifier input and a first amplifier output, the first amplifier output being coupled to the first output node, wherein the amplifier is configured to produce the second signal at the first amplifier output based on a signal at the first amplifier input;
• a first resistive element connected electrically in series between the first input node and the first amplifier input;
• a second resistive element coupled electrically in series between the first node and the first amplifier input;
• a third resistive element coupled between the first amplifier output and the first node;
• a first capacitive element coupled between the first amplifier output and the first amplifier input;
• and
• a second capacitive element connected between the first node and the second node.