International Business Machines Corporation

Joshua C Park

Xiangdong Zhang

David R Helms

Phillip Antognetti

James M Moniz

Scott Munro

Carl Stuebing

Jim Griffiths

Lawrence E Larson

Paul P Chominski

Xiaodong Wang

Jonathan L Kennedy

In a multiple stage transmitter, and analog signal is modulated and mixed to produce a radio frequency output. A separate mixing frequency signal is provided to each stage. A single frequency synthesizer is used rather than a plurality of frequency synthesizers. In a two-stage system, first and second dividers each receive the output of the frequency synthesizer and deliver a mixing signal to the first and second stages respectively. The modulus of each divider may be selected to minimize spurious signals.

Multistage modulation architecture and method in a radio

A bandgap reference voltage circuit having a bandgap start-up circuit for initiating operation of the bandgap reference voltage circuit, a bandgap core circuit for developing a bandgap reference voltage, and a bandgap output circuit for supplying a bandgap reference voltage. The bandgap start-up circuit is connected to a low impedance leg in the bandgap core circuit and the bandgap output circuit has a feedback circuit that is connected to a high impedance leg in the bandgap core circuit. The connection of the bandgap start-up circuit to the low impedance leg of the bandgap core circuit eliminates the possibility of metastable operation of the bandgap reference voltage circuit. This bandgap reference voltage circuit can be used in battery powered units having reduced supply voltages as low as, for example, 1.7V and the arrangement of the feedback circuit of the bandgap output circuit allows supplying of reference voltages greater and less than typical bandgap voltage.

Bandgap reference voltage circuit

A transconductance amplifier and method for improving the phase response and linearity. A differential amplifier circuit receives differential signals for amplification on respective bases of input bipolar transistors. The transistors amplify a small signal received on the based connections to produce an amplified output current. The differential amplifier circuit is connected to load impedances which form a cascode transconductance amplifier output stage. Feedback transistors provide a feedback voltage from the emitters of each of the different bipolar transistors to the base, improving the linearity of the differential amplifier. Phase compensation is provided by cross coupling through first and second capacitors a portion of each individual differential signal component to the base connections of the differential amplifier input transistor.

Highly linear high-speed transconductance amplifier for Gm-C filters

A bias network for a radio frequency signal power amplifier. A current source is connected to a source of band gap voltage and produces a current proportional to the voltage. A reference voltage circuit receives the current and produces a voltage which is proportional to the current, as well as changes in temperature. An operational amplifier is used to connect the reference voltage to the power amplifier, so that the power amplifier is effectively isolated from the reference voltage circuit and current bearer circuit. A power amplifier breakdown protection circuit is connected across the output of the operational amplifier for diverting avalanche current produced form the power amplifier away from the power amplifier when the power amplifier output is mismatched through the antenna. Baseband signal transmission from the power amplifier to the bias network circuit is also significantly reduced, thus avoiding the generation of spurious radiation components.

Active bias network circuit for radio frequency amplifier

A voltage regulator that establishes a bandgap voltage reference and achieves output voltage regulation with a single feedback loop. The bandgap voltage reference is established by equal current flow through each of two branches of a proportional to absolute temperature current mirror. The equal current flow through the two branches of the proportional to absolute temperature current mirror is achieved by the feedback loop controlling the current flow in response to the bandgap voltage reference. This same feedback loop, responsible for establishing the bandgap voltage, also establishes the regulated output voltage through a pass transistor by means of maintaining a fixed voltage ratio between the bandgap voltage and the regulated output voltage through a resistor string.

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Medford, MA, United States of America

Joshua C Park