| dc.description.abstract | This goal of this work is the development of wideband six-port receiver with
compact size. This receiver is composed of six-port network, power detectors and
analog substractors. In order to achieve widewidth band and compact size
simultaneously, bridged-T coil-based six-port network realized by the integrated
passive device (IPD) process is proposed. The measured 10-dB return loss bandwidth
is from 1.28GHz to 2.81GHz and the corresponding fractional bandwidth is 78.5%.
Furthermore, this compact six-port network exhibits a circuit size of only 7.78
mm×7.94 mm, which corresponds to an electrical size of 0.051λ0×0.052λ0 at f0 =
1.95GHz. Next, shottcky diodes are used to implement wideband power detectors with
a center frequency f0=1.95GHz and 10-dB return loss bandwidth from 1.06GHz to
2.4GHz. Parameter studies to improve the sensitivity and conversion efficiency has also
been done. Then, analog subtractors are used to obtain the difference between two
power detector’s outputs to give the demodulated I/Q signal. This work also presents
two subtractor designs for high sensitivity or high bit rate considerations. Lastly, four
power detectors, two analog subtractors, and the six-port network IPD chip are
integrated in a PCB to realize the six-port receiver front-end. The measured 10-dB
return loss bandwidth for the RF port is from 1.4GHz~2.55GHz (FBW = 58.97%) and
that for the LO port is from 1.35GHz~2.75GHz (FBW = 71.79%). The circuit size of
the proposed receiver front end is about 27.71mm×45.72mm, which corresponds to an
electrical size of 0.18λ0×0.3λ0 at f0=1.95GHz. The receiver is tested under three kinds
of modulation scheme, i.e., QPSK, 16-QAM and 64-QAM. The proposed six-port
receiver frond end can cover the frequency band from 1.6GHz to 2.4GHz. For the
designⅠ, under a data rate of 1Msps and a LO power of 0 dBm, the measured RF port
sensitivity for 64-QAM modulation is -35dBm, and the maximal data rate is 5Msps.
III
For the designⅡ under a data rate of 5Msps and a LO power of 0 dBm, the RF port
sensitivity for 64-QAM modulation is -15dBm but a maximal data rate of 20Msps can
be achieved. The proposed receiver front end design maintains the advantages of low
circuit complexity and high bandwidth of the conventional six-port receiver, while the
circuit size is significantly reduced by using bridged-T coils. The proposed receiver can
accommodate multiple modulation schemes. It can be further integrated with a low
noise amplifier, a synthesizer, and baseband circuits to implement a software defined
radio receiver for handheld wireless communication devices. | en_US |