|
A microwave photonic mixer for up and down-conversion with high spurs suppression and image rejection is proposed. Dual parallel in-phase and quadrature (I/Q) modulators and 90-degree electrical hybrid couplers (HCs) are used to realize carrier-suppressed single-sideband (CS-SSB) modulation. The +1/-1st-order sideband of the local oscillator (LO) can be selected by the tunable optical bandpass filter (OBPF) to achieve both up and down-conversion. In the upconversion, a wide upconverted radio frequency (RF) frequency range of 15-37 GHz is achieved. A broad downconverted bandwidth of 8-40 GHz is obtained in the downconversion. Furthermore, a Brillouin-assisted notch filter is used to attenuate the image signal to compensate for the incomplete filtering introduced by the OBPF. In this way, an image rejection ratio (IRR) of more than 60 dB can be obtained when the downconverted intermediate frequency (IF) is 2 GHz. Moreover, the spurs suppression ratio is over 50 dB for both up and downconversion. To the best of our knowledge, this is the highest reported spurs suppression in a microwave photonic mixer.
|
