Lucent Technologies Inc.

Agere Systems Guardian Corp.

Brian K Horton

Paul C Davis

Milton L Embree

Kirk B Ashby

Joseph Harold Havens

A four-quadrant mixer is disclosed which has a low noise factor. The indeterminate common-mode voltage that may accompany the modulating signal is suppressed and replaced by a common-mode quiescent voltage designed to establish a predetermined quiescent biasing current through the mixer transistors common biasing resistors so that the mixer may be driven in common-mode by the modulating signal and differentially by the local oscillator signal. Advantageously, a larger value emitter biasing resistor can be used with the same value of emitter current that would obtain in a comparable four-quadrant Gilbert Mixer or, conversely, larger values of emitter current can be specified to establish a desired level of signal to noise ratio.

Low-noise mixer

There is disclosed a transconductance amplifier receives a voltage input and provides a current output. The transconductance amplifier includes a current mirror having a lowpass filter between transistors implementing the current mirror.

Transconductance amplifier with wideband noise filtering

A power-conserving, linear and broad band RF amplifier, suitable for use at more than one band in the ultra-high frequency regions allotted to radiotelephone transceivers, employs an emitter-follower output transistor to deliver the nominal 1.0 milliwatt RF power to a single-ended load from a low voltage battery, typically 2.7 v. dc, without the use of output coupling transformers. The amplifier receives only a small differential input signal from the preceding mixer or multiplier stage having a typical peak-to-peak magnitude of 0.3 v. The differential input signal is applied to the emitters of a pair of transistors whose bases are interconnected, one transistor of which (B6) is diode-connected in a current-mirror configuration and the other (B5) of which is configured in a common-base connection with emitter degeneration. The signals are summed at the collector of the common-base transistor to deliver a substantial voltage swing, illustratively 1.7 volts peak to peak, which is large enough to drive the base of the emitter-follower output transistor (B3) without requiring the high standby current in the emitter-follower normally required to maintain an emitterfollower in Class A operation.

Low-voltage radio frequency amplifier

The present invention provides an RF transmitter network for cellular telephone systems. The network includes power amplifier circuitry which coupled to a closed loop control system to provide a controllable RF amplitude envelope for the output power of the amplifier circuitry over a dynamic range of between about 5 milliwatts and about 3200 milliwatts.

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Sinking Spring, PA, United States of America

Brian K Horton