Method and frequency agile pre-distorted transmitter using programmable digital up and down conversion

A transmitter operable over a wide range of frequencies including a plurality of predetermined frequency bands, comprising:

• a baseband processing unit configured to receive digital complex baseband input signals and a first digital feedback signal, to compare the digital complex baseband input signals with the first digital feedback signal, and to apply a pre-distortion function to output pre-distorted signals corresponding to the digital complex baseband input signals, said pre-distortion function being adjustable based on the comparison of the first digital complex baseband input signals and the digital feedback signal;
• transmit signal paths connected to the baseband processing unit, each of the transmission paths being configured to digitally up-convert one of the pre-distorted signals to one of the frequency bands, to convert the up-converted signal into an analog signal, to amplify the analog signal and to transmit the amplified analog signal, wherein the transmit signal paths include a programmable digital up-converter to up-convert one of the pre-distorted signals, wherein the programmable digital up-converter comprises a complex baseband tuner, a digital up-sampler, a complex channel selection filter, a quadrature modulator, and a rate change filter configured to change a sample rate of a signal being processed in said programmable digital up-converter;
• and
• a feedback signal path configured to receive at least one analog feedback signal which corresponds to the transmitted signals, to convert said at least one analog signal into a second digital signal at a fixed sampling rate, to digitally down-sample the second digital signal, and to output the down sampled signal as the first digital feedback signal to the baseband processing unit.

A method of manufacturing a transmitter operable over a wide range of frequencies including a plurality of predetermined frequency bands, the method comprising:

• mounting a programmable digital up-converter, a digital to analog converter, and an analog filter, along a transmission path on a substrate or a circuit board, between a baseband processing unit configured to output a pre-distorted signal and a power amplifier, wherein the mounting of the programmable digital up-converter comprises mounting a complex baseband tuner, a digital up-sampler, a complex channel selection filter, a quadrature modulator, and a rate change filter between the baseband processing unit and the digital to analog converter, on the transmission path, wherein the rate change filter is configured to change a sample rate of a signal being processed in said programmable digital up-converter;
• and
• mounting an attenuator, an analog to digital converter and a programmable digital down-converter, along a feedback path on the substrate or the circuit board, between the power amplifier and the baseband processing unit, wherein
• the programmable digital up-converter is configured to convert a pre-distorted baseband signal into a digital signal in a selected one of the predetermined frequency bands according to at least one first control input,
• the programmable digital down-converter is configured to convert a digital feedback signal to a lower sample rate based on at least one second control input, into a lower sample rate digital feedback signal, and
• the baseband processing unit is configured to compare a digital complex input signal with the lower sample rate digital feedback signal, and to generate the pre-distorted baseband signal based on a digital complex input signal using a pre-distorting function, which is adjustable based on the comparison of the digital complex input signal and the lower sample rate digital feedback signal.