Direct-conversion is an alternative wireless receiver architecture to the well-established superheterodyne, particularly for highly integrated, low-power terminals. Its fundamental advantage is that the received signal is amplified and filtered at baseband rather than at some high intermediate frequency. This means lower current drain in the amplifiers and active filters and a simpler task of image-rejection. There is considerable interest to use it in digital cellular telephones and miniature radio messaging systems. This paper briefly covers case studies in the use of direct-conversion receivers and transmitters and summarizes some of the key problems in their implementations. Solutions to these problems arise not only from more appropriate circuit design but also from exploiting system characteristics, such as the modulation format in the system. Baseband digital signal processing must be coupled to the analog front-end to make direct-conversion transceivers a practical reality.

Direct-conversion radio transceivers for digital communications

Radio frequency integrated circuits (RFICs) are the building blocks that enable every device from cable television sets to mobile telephones to transmit and receive signals and data. This newly revised and expanded edition of the 2003 Artech House classic, "Radio Frequency Integrated Circuit Design", serves as an up-to-date, practical reference for complete RFIC know-how. The second edition includes numerous updates, including greater coverage of CMOS PA design, RFIC design with on-chip components, and more worked examples with simulation results. By emphasizing working designs, this book practically transports readers into the authors' own RFIC lab so they can fully understand how these designs function. This title is suitable for radio frequency integrated circuit (RFIC) design engineers; radio systems architects; researchers and developers of RFIC technology; and, graduate level electrical engineering students.

Radio Frequency Integrated Circuit Design

A single planar antenna for use in two frequency bands includes radiating portions for the two bands joined by a connecting portion and spaced from a ground plane. Each radiating portion is formed as a planar inverted F-antenna. A grounding pin interconnects the connecting portion and the ground plane and a single feed pin connects the connecting portion to the input/output port of transceiver circuitry.

Planar dual frequency band antenna

A grid array assembly is provided employing a thin copper or steel carrier frame having apertures extending longitudinally of the frame. A series of semi-flexible substrate printed circuit boards are mounted in seriatim to peripheral edges of the apertures, the circuit boards including bonding pads and metallization on a first surface and conductive vias in the circuit boards extending to a second opposite surface containing a contact pad array. The carrier strip with the mounted circuit boards are passed to a station where an IC die is mounted on the board first surface, wire bonds are placed from the die to the bonding pads and the assembly encapsulated using a portion of the carrier strip as a mold gate to form a package body. Subsequently each grid array assembly is singulated from the carrier strip.

Grid array assembly of circuit boards with singulation grooves

An electronic filter includes a substrate, a ground conductor, an input, an output, a first microstrip line positioned on the substrate and electrically coupled to the input and the output, and a first tunable dielectric varactor electrically connected between the microstrip line and the ground conductor. The input preferably includes a second microstrip line positioned on the substrate and including a portion lying parallel to the first microstrip line. The output preferably includes a third microstrip line positioned on the substrate and including a portion lying parallel to the first microstrip line. The first microstrip line includes a first end and a second end, the first end being open circuited and the varactor being connected between the second end and the ground conductor. The filter further includes a bias voltage circuit including a high impedance line, a radial stub extending from the high impedance line, and a patch connected to the high impedance line for connection to a DC source. In a multiple pole embodiment, the filter further includes additional microstrip lines positioned on the filter substrate parallel to the first microstrip line and additional tunable dielectric varactors electrically connected between the additional microstrip lines and the ground conductor.

Microstrip tunable filters tuned by dielectric varactors

An antenna of this invention comprises a first metal plate (102) having a slit (401), a second metal plate (103) opposed to the first metal plate (102) and electrically connected (104) to the first metal plate (102), two metal foils connected to the second metal plate, and a cable (105) for supplying feed signals to the first metal plate (102) and the second metal plate (103), the cable (105) including a first conductor connected to the first metal plate (102) via a capacitor (106) and a second conductor connected to the second metal plate (103).

Antenna for mobile communication

A filter is formed by coupling plural resonators (13i, 13o) via an electromagnetic field. Each resonator comprises a tubular dielectric (1) having at least one flat side surface (3), a through-hole (2) provided in the axial direction of the dielectric, an inner conductor fil m (4) provided on a wall forming the through-hole, and an outer conductor film (5) provided an side surfaces (7,8,9) of the dielectric (1), and resonates in TEM mode in the axial direction by cooperation of the inner conductor (4), outer conductor (5) and the dielectric (1) intervening between them. Each resonator further has a coupling window (6) which is formed by removing a part of the outer conductor film (5) on the flat side surface (3). The resonators (13i, 13 0 ) are disposed so that their flat side surfaces (3) having the coupling windows (6) contact eecb other, and are couled together via electromagnetic field through the coupling windows.

Dielectric filter with a quarter wavelength coaxial resonator

This paper describes a high-efficiency linear power amplifier using an envelope feedback method for a digital cellular telephone. Adjacent channel interference due to the amplitude and phase distortions of the amplifier is analyzed for a π/4-shift QPSK modulation scheme. From the analysis amplitude error compensation circuits are proposed and the limit of phase-shift variation caused by AM/PM conversion is discussed. the drain power efficiency of 50 percent at the low operation voltage of 5.8 V is achieved experimentally.

A high-efficiency linear power amplifier using an envelope feedback method

This is a PLL frequency synthesizer having a reference divider for dividing a reference source signal, and an RF divider for dividing the output of a voltage controlled oscillator, wherein when changing over the frequency, first the division value of the RF divider changes periodically to become a fractional division value in average, and after the frequency is nearly changed over, the RF divider is set in a conventional integer division operation, therefore, the frequency can be changed over at high speed by the fractional division operation high in reference frequency, and after the changing, a low spurious signal characteristic may be realized.

Fast frequency switching synthesizer

A coaxial line-to-microstrip line transition device including a coaxial line, a microstrip line circuit, and a conductive connection part The inner conductor of the coaxial line is connected with a microstrip line of the microstrip line circuit The connection part includes a semi-cylindrical plate which is connected with the outer conductor of the coaxial line by grasping it, and a flat plate which is connected at a surface thereof with a earth layer surface of the microstrip line circuit The microstrip line is mounted on one surface of a dielectric substrate, and the earth layer is mounted on the other surface of the dielectric substrate The dielectric substrate is mounted on a chassis which is either provided separately or shared by the flat plate of the connection part which is extended in size Preferably, a through-hole is provided at least one of the semi-cylindrical plate and the flat plate to be filled with a conductive material

Tomoki Uwano

Papers

Antenna for mobile communication

Dielectric filter with a quarter wavelength coaxial resonator

A high-efficiency linear power amplifier using an envelope feedback method

Fast frequency switching synthesizer

Coaxial line-to-microstrip line transition device