Sylvia Lin

Quadrature direct conversion receiver integrated with planar quasi-Yagi antenna

A compact receiver front-end comprised of subharmonic direct conversion mixers integrated with a planar quasi-Yagi antenna is presented. The front-end generates I and Q baseband outputs, using the quasi-Yagi antenna as a circuit element to split the incoming signal into an I and Q component. Furthermore, the subharmonic design cancels even mixing products, thereby improving even-order distortion. Downconversion and demodulation of a QPSK modulated RF carrier signal is demonstrated successfully with a C-band prototype.

A low noise active integrated antenna receiver for monopulse radar applications

A low noise active integrated antenna receiver is presented. This new design consists of a pair of low noise amplifiers (LNA) integrated on each feed of a dual-feed planar quasi-Yagi antenna. The outputs of the LNAs are combined to form a sum and difference radiation pattern suitable for monopulse radar applications. Simulation and measurement methodology for designing a low noise active integrated antenna receiver is also presented. A peak gain of 7.7 dB and minimum noise figure of 3.6 dB is measured for a C-band prototype.

C-band direct conversion receiver front-end using a resistive FET mixer

A C-band direct conversion receiver front-end based on a resistive FET mixer has been developed. Resistive FET mixers, as opposed to other configurations, require only gate bias and no drain bias. Thus the baseband signal can be easily filtered from the drain terminal. The resistive FET mixer is integrated with rectangular microstrip patch antenna, yielding a compact receiver front-end. A prototype was constructed and demonstrated satisfactory demodulation of a BPSK modulated RF signal.

A Quasi-Optical Sub-Harmonic Self-Oscillating Mixer

A sub-harmonic self-oscillating mixer (S-SOM) integrated with an inset-fed microstrip patch antenna is developed for receiver front-end applications. The circuit is designed as a sub-harmonic mixer in order to facilitate scaling to millimeter wave frequencies. A prototype design at C-Band was measured to have isotropic conversion loss of 10.25 dB for the second harmonic mixing product.

Toward more functional millimeter wave front ends

The millimeter-wave spectrum of 57-64 GHz has been allocated for use of unlicensed applications. It provides wide bandwidth and increased channel capacity for future communication systems. RF front ends combined with quasi-Yagi antenna based on Active Integrated Antenna (AIA) concept offer benefits of compact circuit design operating on limited source power and reduction of loss which are all desirable for millimeter wave applications. This paper summarizes our recent research toward the development of more functional millimeter wave front ends. V-band circuits were implemented to realize functional blocks for millimeter wireless communications, and C-band circuits and a beamformer for smart antenna system were implemented and tested for preliminary knowledge for realization of system in V-band.