Error signal processing systems for generating a digital error signal from an analog error signal

A method for controlling the output of a transmitter that generates an analog output signal based on an input signal, the method comprising:

• generating a digital reference signal having a first number of bits based on a baseband input signal;
• converting the digital reference signal to an analog reference signal;
• generating an analog error signal in response to a difference between the analog reference signal and the analog output signal;
• amplifying the analog error signal by a gain factor prior to converting the analog error signal to a digital error value;
• converting the analog error signal to the digital error value having a second number of bits, the second number of bits being less than the first number of bits;
• generating a digital error signal having the first number of bits by adjusting the digital error value to compensate for the gain factor;
• and
• generating the input signal based on the baseband input signal and the digital error signal.

A transmitter for generating a radio frequency output signal based on a baseband input signal, the transmitter comprising:

• an output control module configured to adjust the baseband input signal based on a digital error signal to produce an adjusted baseband input signal;
• a transmission module coupled to the output control module, the transmission module being configured to generate the radio frequency output signal based on the adjusted baseband input signal;
• a demodulation module coupled to the transmission module, the demodulation module being configured to generate an analog output signal based on the radio frequency output signal;
• and
• an error processing system coupled to the demodulation module and the output control module, the error processing system being configured to:
• generate a digital reference signal having a first number of bits based on the baseband input signal;
• convert the digital reference signal to an analog reference signal;
• produce a difference signal based upon a difference between the analog reference signal and the analog output signal;
• amplify the difference signal by a gain factor;
• convert the difference signal to a digital error value having a second number of bits after amplifying the difference signal by the gain factor, the second number being less than the first number;
• adjust the digital error value by an inverse of the gain factor to obtain the digital error signal having the first number of bits;
• and
• adjust the gain factor based on the digital error value.

An error processing system for determining an error signal based on an input signal and an analog output signal, the error processing system comprising:

• a digital-to-analog converter configured to convert a digital reference signal to an analog reference signal;
• an analog summing element coupled to the digital-to-analog converter, the analog summing element being configured to produce an analog error signal based upon a difference between the analog reference signal and the analog output signal;
• a variable gain amplifier coupled to the analog summing element, the variable gain amplifier being configured to amplify the analog error signal by a gain;
• an analog-to-digital converter coupled to the variable gain amplifier, the analog-to-digital converter being configured to convert the analog error signal into a digital error value;
• and
• a module coupled to the digital-to-analog converter and the analog-to-digital converter, wherein the module is configured to:
• determine the digital reference signal based on the input signal;
• generate the error signal based on the digital error value by scaling the digital error value by an inverse of the gain to compensate for the gain of the variable gain amplifier;
• and
• adjust the gain of the variable gain amplifier based on the digital error value.

A transmitter for generating a radio frequency output signal based on a baseband input signal, the transmitter comprising:

• an output control module configured to adjust the baseband input signal based on a digital error signal to produce an adjusted baseband input signal;
• a transmission module coupled to the output control module, the transmission module being configured to generate the radio frequency output signal based on the adjusted baseband input signal;
• a demodulation module coupled to the transmission module, the demodulation module being configured to generate an analog output signal based on the radio frequency output signal;
• and
• an error processing system coupled to the demodulation module and the output control module, the error processing system comprising:
• a digital-to-analog converter having a first number of bits of resolution to convert a digital reference signal to an analog reference signal;
• an analog summing element coupled to the digital-to-analog converter to produce a difference signal based upon a difference between the analog reference signal and the analog output signal;
• and
• an analog-to-digital converter coupled to the analog summing element to convert the difference signal to a digital error value, the analog-to-digital converter having a second number of bits of resolution being less than the first number of bits of resolution, wherein the error processing system is configured to:
• generate the digital reference signal based on the baseband input signal;
• amplify the difference signal by a gain factor prior to converting the difference signal to the digital error value;
• increase a number of bits of the digital error value to be the same as a number of bits of the digital reference signal;
• shift bits of the digital error value based on an inverse of the gain factor to obtain the digital error signal;
• and
• adjust the gain factor based on the digital error value.