Yi-Chen Lin

A High-Speed HBT Prescaler Based on the Divide-by-Two Topology

This paper demonstrates the Divide-by-4/5 prescalers with merged AND gates in 2 mum GalnP/GaAs heterojunction bipolar transistor (HBT) and 0.35 mum SiGe HBT technologies. By biasing the HBT near the peak transit-time frequency (fr), the maximum operating frequency of a D-type flip-flop (D-FF) can be promoted. At the supply voltage of 5 V, the GalnP/GaAs prescaler operates from 30 MHz to 5.2 GHz, and the SiGe prescaler has the higher-speed performance of 1 GHz ~ 8 GHz at the cost of power consumption.

A 9-GHz dual-modulus 0.18-µm CMOS prescaler using HLO-FF technique

This paper describes the design issues of the dual modulus divide-by-4/5 prescaler with merged AND gates and HLO-FF topologies fabricated in 0.18 mum CMOS technologies. By the two topologies, the propagation delay and the voltage swing can be reduced to improve the maximum operating frequency. Because the CLK transistors operate at higher frequency, how to choose the CLK transistor size and the bias current properly plays an important role. With 2.5 V supply voltage, the divide-by-4/5 prescaler can operate up to 9 GHz.

Characteristics of Integrated RF Transformers on GaAs Substrate

Stacked transformers, coupling stacked transformers, interleave transformers and symmetrical transformers on GaAs substrate are systematically studied in this paper. Two kinds stacked transformer are under study. One has the symmetrical electric property while the other one has a better quality factor for the primary port. The stack transformers have achieved the highest coupling coefficient (~0.9) at the cost of lower self-resonance frequency. The interleave transformers have the identical electric properties for the primary and the secondary ports. However, the layout is incompatible with the differential operation. On the other hand, the symmetrical transformer is compatible with the differential operation and can have the center-tapped biasing option. The data established here provide a useful design library for the GaAs RFIC.

Compact GaInP/GaAs HBT Gilbert Mixers With On-Chip Active LO Balun

A Gilbert micromixer is demonstrated in this paper using GalnP/GaAs HBT technology. The RF, LO, and IF ports of the micromixer are all single-ended using the on-chip active LO balun. The port-to-port isolation has its best performance when the LO signal is balanced. The stand-along micromixer is suitable for hybrid RF system applications. The fully matched high linearity micromixer has the conversion gain of 12 dB, IPIdB of-9 dBm, IIP3 of 1 dBm when input IF=300 MHz, LO=3.5 GHz and output RF=3.8 GHz.

Programmable-gain constant-IF-bandwidth SiGe BiCMOS upconversion micromixer at 2.4/5.8 GHz using current-mode approach

A 2.4/5.8-GHz dual-band programmable-gain upconverter with a constant IF bandwidth is demonstrated using 0.35-µm SiGe BiCMOS technology. Using a current-mode design approach, the input IF bandwidth remains the same at different gain settings. A dual-band LC current combiner is used at the mixer RF output to combine differential signals to a single-ended one at two bands. Then, a wideband amplifier is cascaded after the dual-band mixer. The demonstrated upconverter achieves maximum gain of −4/−3 dB at 2.4/5.8 GHz, respectively. In addition, four gain steps with 5-dB gain difference between each step are controlled by a two-bit digital circuit. The total current consumption is 26 mA at a 4-V supply.

Isolation performance of sub-harmonic Gilbert mixers

This paper analyzes the isolation mechanisms between two types of sub-harmonic Gilbert mixers in detail. The proposed double-compensated structure without additional output balun has inherent LO and 2LO cancellations at each port, which can greatly improve 2LO-to-RF leakage for the down or up converters. The experimental results reveal that the proposed double-compensated structure applied in a 2-um GalnP/GaAs HBT sub-harmonic down converter achieves a 2LO-to-RF isolation of 80 dB, and its fLo/2fLo leakage is insensitivity to LO power when compared with that of a conventional single-stacked cell.