K.S. Ang

Analysis and design of impedance-transforming planar Marchand baluns

A technique for designing impedance-transforming baluns is presented in this paper. It is based on the Marchand balun with two identical coupled lines. By varying the coupling factor of the coupled sections, a wide range of impedance transforming ratios can be achieved. In addition, a resistive network added between the balun outputs is proposed to achieve balun output matching and isolation. Microstrip baluns, matched at all ports, for transforming from a 50-/spl Omega/ source impedance to 40-/spl Omega/ as well as 160-/spl Omega/ load terminations are realized to demonstrate the technique.

Converting baluns into broad-band impedance-transforming 180/spl deg/ hybrids

A technique for converting baluns into 180/spl deg/ hybrids by adding an in-phase power splitter is presented in this paper. Incorporating the broad-band antiphase and in-phase power splitting characteristics of the balun and power splitter results in a 180/spl deg/ hybrid with broad-band characteristics. This technique also provides a means of achieving perfect matching and output isolation for three-port lossless baluns. Applying this technique to a Marchand balun will result in a broad-band impedance-transforming 180/spl deg/ hybrid. Simple design equations based on the scattering matrix are presented. These theoretical results are validated by an experimental 180/spl deg/ hybrid using a coupled line Marchand balun. It achieves amplitude balance of 0.5 dB and phase balance of less than 5/spl deg/ from 1.2 to 3.2 GHz.

Balanced monolithic oscillators at K- and Ka-band

A technique for generating accurate antiphase signals is presented in this paper. Monolithic oscillators at 20 and 40 GHz are realized using this technique. These oscillators have dual outputs that are mutually locked in antiphase. The inherent amplitude and phase balances between the output signals are verified. This is achieved by direct measurement using injection-locking polar diagrams, as well as low-frequency measurements of the down-converted oscillator outputs. The operation of the balanced oscillator as a multidevice power-combining oscillator is also investigated. Improvements of phase noise reduction and frequency stabilization are demonstrated at the combined oscillator output. This new oscillator topology shows significant potential in balanced circuits like mixers, multipliers, and modulators where circuit performance relies on the precise generation of the balanced signals.

40 to 90 GHz impedance-transforming CPW Marchand balun

It is shown analytically that impedance-transforming planar Marchand baluns can be designed. A GaAs monolithic CPW balun, transforming between a 50 /spl Omega/ source impedance and 160 /spl Omega/ load terminations has been realised to demonstrate the technique. The balun operates from 40 to 90 GHz with excellent performance.

A new class of multisection 180/spl deg/ hybrids based on cascadable hybrid-ring couplers

A new class of multisection 180/spl deg/ hybrids is presented in this paper. It is based on the hybrid-ring coupler that has been reconfigured such that multiple sections can be conveniently cascaded together. The main limitations of the conventional hybrid-ring coupler are its limited bandwidth, large size, and the impracticably high-impedance levels required for large power-split ratios. These limitations are readily overcome using the multisection cascadable 180/spl deg/ hybrids. Simple design equations based on the scattering matrix and experimental verifications of the theoretical results for two-section 180/spl deg/ hybrids are presented.

Monolithic resistive mixers for 60 GHz direct conversion receivers

Single-ended and balanced monolithic mixers for direct conversion at V-band are presented. Resistive PHEMTs are employed with reactive feedback between gate and drain, and IF extraction from the source. Low conversion loss is achieved with high isolation and low intermodulation. Successful demodulation of a 1 Mbit/s BPSK signal at 60 GHz demonstrates the technique for millimeter wave direct conversion receivers.

A compact MMIC balun using spiral transformers

A MMIC balun has been realised using spiral transformers in a Marchand configuration. This arrangement results in a simple, compact design with good performance. Using standard foundry processing, amplitude balance of 0.2 dB and phase balance of 10/spl deg/ was achieved from 2 to 6 GHz.

Low-cost millimeter-wave transmitter using software radio techniques

A low-cost millimeter-wave transmitter architecture comprising a fixed-frequency Gunn oscillator feeding a vector modulator is presented. Multifunction signal processing in software is applied to a 60 GHz direct carrier modulation transmitter for the first time.

Design and Performance of A Novel Balanced Self-Oscillating Mixer

A balanced self-oscillating mixer has been fabricated and tested. By utilising the symmetrical configuration technique, the circuit provides anti-phase output signals. Its inherent mixing is given by the non-linear mechanism of an active device. Therefore, anti-phase intermediate frequency performance has been investigated. In addition, the RF port is taken into account in order to obtain conversion gain. Unlike the typical mixer, the balanced self-oscillating mixer can achieve smaller size and consume less power.

Transmission-line stabilized monolithic oscillators

A novel technique for frequency stabilization and phase-noise reduction of monolithic oscillators is presented in this paper. It employs simple transmission-line resonators, which are many wavelengths long to increase the oscillator quality factor. Monolithic oscillators at 20 and 40 GHz are realized for the application of this technique. Phase noise reduction of more than 20 dB was achieved for both oscillators. The single-sideband phase noise obtained was -100 dBc/Hz at 100-kHz offset for the 20-GHz oscillator and -90 dBc/Hz at 1-MHz offset for the 40-GHz oscillator. The approach is implemented by using readily available transmission lines, which are open- or short-circuited at one end and connected to the monolithic-microwave integrated-circuit (MMIC) oscillator at the other end. Thus, it presents significant potential in the development of low-cost MMIC oscillators with enhanced noise performance.