Lianfu Liu

  • Citations Per Year
Learn More
In this paper, an approach of developing high agility and resolution millimeter-wave synthesizer architecture without using PLL (Phase Locked Loop) is proposed. Using the frequency multiplying of DDS output signal to provide the local oscillators instead of PLL in traditional three frequency conversions scheme, with good frequency configuration and optimal(More)
In this paper, a novel multiple-tunable frequency synthesizer structure to achieve both high frequency resolution and fast switching speed without degradation of spurious performance is proposed. According to this structure, a high performance millimeter-wave frequency synthesizer with low spurious, low phase noise, and fast switching speed, is developed.(More)
In this paper, a Ka band broadband bandpass filter with substrate integrated waveguide (SIW) technology is presented and investigated with simulation and experiment, which can provide 32.7% fractional bandwidth at the center frequency of 35GHz. In order to connect with microstrip circuits, an SIW to microstrip transition is included in this design.(More)
We investigate the parameter estimation problem of polynomial phase signals with time-varying amplitudes. For many models of polynomial phase signals with time-varying amplitudes, the parameters can be expressed by the coefficients of its finite-order Taylor series expansion. And the estimation of phase and amplitude parameters can be converted to the(More)
Waveguide T-junction and directional couplers are widely used in microwave/millimeter wave systems, because its circuit is simply and easily to be designed and fabricated. In this paper, a ka-band E-plane rectangular waveguide power divider is proposed and optimized. The first level of the network is the T-junction, which can halve the power for the first(More)
This paper presents a wide-band receiver at 2.4GHz and 5GHz for 4×4 MIMO wireless communication system. This design is proposed and realized using super heterodyne architecture solution. Dual conversion structure is used in this receiver system. The receiver benefits from RF part, control part and phase shifter part. The carrier of this transceiver(More)
TDD is one of the duplex technologies used by the mobile communication system, and its role is to separate the receiving and transmitting channel (the uplink or downlink). This paper presents a high speed TDD baseband data processing system realized on the FPGA. Through the data transceiver loop method, it's verified that the transceiver switching rate of(More)
This paper presents a 65–85 GHz 5-bit passive phase shifter at the desired frequency of 77 GHz, using CMOS switches available in the 0.13 µm SiGe BiCMOS process. The phase shifter is based on a low-pass π-network and CMOS passive transistors. The RMS phase error, the insertion loss and the VSWR is less than 3.5°, −20 dB(More)
The paper firstly studies two novel power-dividing structures which are used in solid-state power amplifiers. Two structures are similar to each other except the air holes. According to the EM simulation, the return loss of first one is smaller than −20dB in the required bands, and the second about −25dB. This paper researches the difference(More)
Co-Channel Dual Polarization (CCDP) technology is an efficient way to double the link capacity in modern communication system. However, the consequent polarization interferences become an inevitable problem to fight. Therefore, a Cross-Polarization Interference Canceller (XPIC) is necessary against the cross-talks. This paper focuses on the baseband XPIC(More)