One very practical way to provide gate drive to the final RF amplifier is to use one of the several RF driver ICs available for the purpose. Some of these driver ICs will operate on 30 mHz or higher. If you chose the correct driver IC, it is possible to provide almost square wave drive to the gates of the RF amplifier MOSFETs, which can result in more efficiency and will significantly reduce the possibly of parasitic oscillations in the RF amplifier. Since the driver is not tuned, it is possible to operate the driver on multiple bands, making multi band operation much simpler. The driver ICs generally take a standard 5V TTL input signal. As of this writing, IXYS / DEI appear to provide the most robust driver ICs with respect to RF service. The IXDD414 will drive a single FQA11N90 MOSFET quite well at 7 mHz and below. These devices cost approximately $3.00 each. One driver IC must be provided for each output MOSFET. The DEI DEIC420 will drive up to 5 FQA11N90 MOSFETs on 80 and 160 meters. The DEIC420 currently costs around $31.00.

    Gate drivers are electronic circuits that apply correct power levels to metal-oxide field-effect transistors (MOSFETs) and insulated gate bipolar transistors (IGBTs). With power-MOSFETs, gate drivers can be implemented as transformers, discrete transistors, or dedicated integrated circuits (IC). They can also be integrated within controller ICs. Partitioning the gate-drive function of controllers that use pulse width modulation (PWM) improves controller stability by eliminating the high peak currents and heat dissipation needed to drive power-MOSFETs at very high frequencies. With IGBTs, gate drivers serve as isolation amplifiers and often provide short-circuit protection. Because of their insulated gates, IGBTs require a continuous gate circuit in order to sustain gate current.

    There are four basic types of gate drivers. High-side gate drivers are used to drive power-MOSFETs or IGBTs that are connected to a positive supply and not ground referenced (floating). Conversely, low-side gate drivers are used to drive power-MOSFETs and IGBTs that are connected to a negative supply. Dual gate or half-bridge gate drivers have both low-side and high-side gates. Three-phase drivers derive their name from the fact that they are used in three-phase applications. These drivers have three independent low-side and high-side referenced output channels. Typically, gate drivers have 1, 2, or 4 output channels. Their output voltage can be either inverted or non-inverted.

    Gate drivers vary in terms of performance specifications and features. Performance specifications include output voltage, peak output current, supply voltage, rise time, fall time, propagation delay, power dissipation, switching frequency, and operating temperature. Rise time is the time needed for the output voltage to increase from 10% to 90% of maximum. Conversely, fall time is the time needed for the output voltage to decrease from 90% to 10% of the maximum. Features for gate drivers include input threshold, integrated protection, dead time control and internal regulation. Input thresholds consist of transistor-transistor logic (TTL), complementary metal-oxide semiconductor (CMOS), pulse width modulation, and combinations such as TTL/CMOS and TTL/PWM. Integrated protection types include over-voltage protection (OVP), over-voltage protection current (OVPC), undervoltage lockout (UVLO), thermal shutdown (TSD), and over-current protection (OCP). Dead time control eliminates shoot-through currents. Internal regulation controls the level of the output voltage.

    Gate drivers are available in a variety of IC packages. Basic types include ball-grid array (BGA), chip scale package (CSP), quad flat package (QFP), small outline package (SOP), single in-line package (SIP) and dual in-line package (DIP). Fine-pitch land grid array (FLGA) and SC-70, one of the smallest IC packages, are also available. Packing methods for gate drivers include tape reels, tubes, bulk packs, and trays or rails. Screening levels such as commercial, industrial, and military indicate the supported temperature range as well as mechanical and electrical specifications. Some listed gate drivers are still in development. Others are in full production. Devices that are discontinued are no longer available from the manufacturer, but may still be found in the supply chain.

    Posted by adminbot on Dec 29 2010 09:28
    IR Gate Drive ICs have ten times better delay matching performance than opto-coupler-based solutions. Delay matching between the low-side and high-side driver is typically within ± 50ns (and as low as ± 10ns for some specialty products), allowing complete dead-time control for better speed range and torque control in motor drive applications. Fast switching also reduces switching power losses and allows leveraging the full benefits of the fastest IGBTs available on the market today for better torque control over a wider speed range.
    EL SEGUNDO, Calif. — International Rectifier, IR® (NYSE: IRF), a world leader in power management technology, today introduced the IRS233x(D) family of three-phase gate driver ICs for low-, mid-, and high-voltage motor drive applications including permanent magnet (PM) motor drives for air conditioners, washing machines, pumps and fans, and micro, mini and general purpose inverter drives.

    Posted by adminbot on Dec 29 2010 09:30
    TI Home > Power Management > AC/DC and DC/DC Power Supply > MOSFET Driver

    Posted by adminbot on Dec 29 2010 12:18
    Integrated Circuits for Driving Laser Diodes
    IXYS RF's MOSFET driver ICs are ultra-fast, high current drivers optimized for driving IXYS RF MOSFETs in a variety of applications requiring high-efficiency performance. These include RF generators, laser diode drivers, pulse generators, as well as motor drive and power conversion applications. IXYS RF MOSFET DRIVER ICs are designed to switch MOSFETs and IGBTs with minimum switching times.

    Posted by adminbot on Dec 30 2010 10:09