Fairchild Semiconductor Corporation

Raytheon Company

Integrated Circuit Systems, Inc.

Ignatius S Bezzam

David W Ritter

Michael Yimin Zhang

Gregory Richmond

Herbe Q Chun

Ioan Stoichita

A radio frequency synthesizer receives a relatively low frequency input signal and synthesizes from it a high frequency output signal whose frequency can be programmed to change in fine steps, for use e.g. in cordless telephone. The frequency synthesizer includes three linked phase locked loops with a single side band mixer in one embodiment coupling two of the phase locked loops together. This provides an output signal free of in-band frequency spurs within the spacing of two channels. The synthesizer can be integrated in a single chip with a narrowband FM modulation circuit. In spite of using a novel synthesizer to achieve monolithic integration, the user programming interface and control value equations are the industry standard format.

Multiple loop radio frequency synthesizer

A wide-band, high-order, programmable video filter is implemented using transimpedance-based active integrators. An input voltage which may for instance represent a composite video signal is converted to a current in a linear manner using resistors and provided to a current amplifier at low impedance virtual ground nodes. The current is multiplied by a gain factor .beta..sub.R within the current amplifier and supplied to integrating capacitors connected in a feedback configuration around a high input impedance differential amplifier to establish an integrated differential voltage output. The transimpedance-based active integrators may be interconnected to realize wide-band, high-order video filters suitable for use in accordance with CCIR 601 standards. Input voltage swings are not restricted by a transistor's limited range of linear operation or voltage swing limitations of internal nodes but rather may allowed to swing as long as the bias currents sustain input current excursions. Thus, pre-filter attenuation and post-filter amplification is not required, thereby allowing CCIR 601 standard compliant video filters to be fabricated, in accordance with the present invention, as a single chip IC.

Large swing wide band programmable active filter

A CMOS rail-to-rail input/output operational amplifier has constant supply current with respect to the input signal's common mode voltage. By use of current bleeders, i.e. a smaller transistor of opposite conductivity type connected in parallel with each transistor in the differential pair of transistors, there is provided constant transconductance and constant supply current for rail-to-rail operation with respect to the positive and negative supply voltages. This allows production of a low cost, high performance and small area rail-to-rail input/output operational amplifier.

CMOS rail-to-rail input/output amplifier

A semiconductor integrated circuit to provide a low distortion, large swing intermediate frequency wherein the circuit includes the function of mixing, filtering, and amplification on a single chip. A pair of differential currents are obtained from the mixer, the differential currents are filtered and conditioned, converted to a pair of differential voltages and amplified to obtain the low distortion, large swing intermediate frequency.

Low distortion large swing frequency down coverter filter amplifier

A wide band, high-order, programmable video filter is implemented using transimpedance-based active integrators. An input voltage which may for instance represent a composite video signal is converted to a current in a linear manner using resistors and provided to a current amplifier at low impedance virtual ground nodes. The current is multiplied by a gain factor .beta..sub.R within the current amplifier and supplied to integrating capacitors connected in a feedback configuration around a high input impedance differential amplifier to establish an integrated differential voltage output. The transimpedance-based active integrators may be interconnected to realize wide-band, high-order video filters suitable for use in accordance with CCIR 601 standards. Input voltage swings are not restricted by a transistor's limited range of linear operation or voltage swing limitations of internal nodes but rather may allowed to swing as long as the bias currents sustain input current excursions. Thus, pre-filter attenuation and post-filter amplification is not required, thereby allowing CCIR 601 standard compliant video filters to be fabricated, in accordance with the present invention, as a single chip IC.

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Mountain View, CA, United States of America

Ignatius S Bezzam