Balun

About: Balun is a research topic. Over the lifetime, 5375 publications have been published within this topic receiving 52256 citations. The topic is also known as: Telephone balance unit.

Antennas for the next generation of low-frequency radio telescopes

Abstract: The next generation of large telescopes for radio astronomy at frequencies below 100 MHz will consist of tens of thousands of wide-band dipole-like antennas, each individually instrumented with a receiver and combined using digital signal processing. At these frequencies, the sensitivity of a telescope is limited by Galactic noise, with the result that even simple dipoles can deliver extraordinary useable bandwidth. In this paper the necessary characteristics for these antennas are explained, some bounds on performance are developed, and a few candidate designs are analyzed. It is shown that antenna systems consisting of simple wire dipoles, a 360 K active balun, and a long coaxial feedline can achieve Galactic noise-limited performance over large portions of the range 10-100 MHz. It is further shown that when these antennas are used as elements in a compact array, their Galactic noise-limited characteristics are not significantly affected.

Highly integrated multi-layer circuit module having ceramic substrates with embedded passive devices

Abstract: A plurality of ceramic substrates are used to manufacture and integrate a highly integrated multi-layer circuit module. Integrated circuit devices are mounted on one or both surfaces of the circuit module whose multi-layer structure is divided into three types of integration regions including inter-connection integration regions, basic passive device integration regions and high frequency passive device integration regions. Connection layers are formed in the inter-connection integration regions for connecting integrated circuits. Basic passive device integration regions include capacitor, resistor and inductor layers. Filters, couplers and baluns are fabricated in the high frequency passive device integration regions. Shielding ground planes are provided for the isolation of devices to prevent electromagnetic interference. Standard input and output contacts are formed on the bottom surface so that the circuit module can be used as a modularized device.

A single-chip CMOS direct-conversion transceiver for 900 MHz spread-spectrum digital cordless phones

Abstract: This fully-integrated transceiver incorporates RF circuits, synthesizer, baseband filters, demodulator, and digital signal processing. The few off-chip components include an ISM band filter, a balun, an RF matching network, an RC loop filter for the PLL, a crystal resonator, and a resistor for biasing. A transmit/ receive (T/R) switch is avoided by sharing a single RF port between transmitter and receiver. An offset cancellation method attenuates offsets in the baseband without sacrificing bandwidth in the direct conversion receiver. Careful circuit design, timing, and layout considerations provide isolation between the sensitive RF signals and the digital switching noise. The IC is in 0.6/spl mu/m CMOS and provides a complete interface between antenna and voiceband codec.

Three-dimensional passive circuit technology for ultra-compact MMICs

Abstract: A novel passive circuit technology of a three-dimensional (3-D) metal-insulator structure is developed for ultra-compact MMICs. By combining vertical passive elements, such as a wall-like microwire for shielding or coupling, and a pillar-like via connection with multilayer passive circuits, a 3-D passive circuit structure is formed to implement highly dense and more functional MMICs. O/sub 2//He RIE for forming trenches and holes in a thick polyimide insulator, low-current electroplating for forming gold metal sidewalls in the trenches or holes, and ion-milling with a WSiN stopper layer for patterning the gold metal are used to produce such a structure. The complete 3-D structure provides miniature microstrip lines effectively shielded with a vertical metal-wall, a miniature balun with low-loss vertical wall-like microwires, and inverted microstrip lines jointed with pillar-like vias through a thick polyimide layer. This technology stages next-generation ultra-compact MMICs by producing various functional passive circuits in a very small area.