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Abstract:A fully integrated system-in-package (SiP) for UHF (860-960 MHz) RFID mobile reader is presented. The SiP is made up of an UHF transceiver, a power amplifier (PA), and two baluns. The UHF transceiver was designed in TSMC 0.18 µm Si CMOS and the PA was developed with InGaP/GaAs hetero-junction-bipolar transistor (HBT) technology. The transceiver IC is fully integrated for mobile UHF RFID applications and the PA has high efficiency and linearity with 24 dBm output power for wireless RFID communications over a distance of 1 m. The total size of the SiP module is 11 mm × 11 mm. The measured data show a transmitter gain of 19.2 dB, total current of 253 mA and adjacent channel power ratio (ACPR) of −41.8 dBc with the second harmonic performance of −57.6 dBc. Also, TX-RX leakage was reduced by careful power amplifier and board designs in small SIP module implementation.

A negative impedance converter (NIC) is applied to resistively loaded vee dipole (RVD) antenna matching. The RVD antenna based on the Wu-King loading profile has large reflection at the feed point because the antenna impedance has high resistance and large negative reactance at low frequencies.To effectively reduce the reflection at low frequencies, the NIC based on operational amplifiers (op-amps) is employed for impedance matching. The matching network is designed such that the RVD antenna is matched to a 75 ohm feeding transmission line. The stability of the network is investigated based on the transient responses obtained from a circuit simulator. The reflection performance of the impedance-matched RVD antenna is measured and shown that the NIC-based matching network improves the impedance matching of the RVD antenna at low frequencies.I.

Negative impedance converter(NIC)-based non-Foster impedance matching is proposed for an electrically small antenna. The antenna considered in this work is a resistively loaded vee dipole(RVD) antenna, which has considerable reflection at the feed point because of its large negative input reactance. The non-Foster matching circuit built near the feed point consists of two-stage NIC circuit and a capacitor connected between the stages. The NIC is realized by using operational amplifiers(op-amps) and resistors. The circuit is designed by considering of the input impedance according to the finite open-loop gain of the practical NICs. The stability test of the impedance-matched RVD antenna is performed. The non-Foster matching circuit is implemented with the RVD antenna. The measured impedance demonstrates that the proposed non-Foster matching circuit effectively reduces the input reactance of the RVD antenna.