Communications device with discriminator for generating intermediate frequency signal and related methods

A communications device comprising:

• a transmitter device comprising an optical source configured to generate an optical carrier signal, and a first modulator coupled to said optical source and configured to modulate the optical carrier signal with a radio frequency (RF) input signal;
• an optical waveguide coupled to said transmitter device;
• and
• a receiver device coupled to said optical waveguide and comprising
• a second modulator configured to further modulate the modulated optical carrier signal with a local oscillator (LO) signal,
• a pair of frequency modulation-phase modulation (FM-PM) discriminators coupled to said second modulator and configured to convert the modulated optical carrier signal to an intensity modulated optical carrier signal based upon the LO signal, each FM-PM discriminator having a transfer function comprising an infinite impulse response (IIR) filter, and
• an optical-to-electrical converter coupled to said pair of FM-PM discriminators and configured to generate an intermediate frequency (IF) signal based upon the intensity modulated optical carrier signal.

A method of frequency converting a radio frequency (RF) input signal, the method comprising:

• modulating an optical carrier signal with the RF input signal using a first modulator;
• further modulating the modulated optical carrier signal with a local oscillator (LO) signal using a second modulator;
• converting the modulated optical carrier signal into an intensity modulated optical carrier signal based upon the LO signal and using a frequency modulation-phase modulation (FM-PM) discriminator coupled to the second modulator;
• and
• converting the intensity modulated optical carrier signal into an intermediate frequency (IF) electrical signal.