Northern Telecom Limited

Nortel Networks Corporation

Kleer Semiconductor Corporation

Ronald Douglas Beards

John Jackson Nisbet

George Khoury

Adrian John Bergsma

Ralph Mason

Samuel Alfred Tiller

Christopher Andrew Devries

Theodore Gregory Carron

An improved receiver architecture and method for a wireless transceiver (e.g. for a headphone) is provided whereby the receiver, advantageously, enables the use of only one synthesizer circuit for both the RF-to-IF and IF-to-base band conversion processes which, in turn, provides for lower power consumption. The receiver includes an injection locked local receiver oscillator (Rx LO) which is used for the first mixing stage (i.e. the RF-to-IF conversion). The Rx LOis thereby able to use a high-level harmonic of a relatively low reference frequency signal produced by that synthesizer (e.g. a fractional-N phase locked loop circuit (PLL)). The receiver further includes a tunable Q-enhanced IF filterand complex sub-sampling and mixing down-conversion circuitry for the second conversion stage (i.e. IF-to-baseband conversion). The sampling frequency used for the second conversion stage is a harmonic of the reference frequency derived from the synthesizer (PLL). For example, transceiver channels may be designed on the basis that the RF frequency fis assigned a value of (n&#xb1;&#xbc;)&#xb7;f, where the frequency fof the PLL may be chosen to be twice the sub-sampling frequency fand the frequency fof the Rx LO may be nine times the frequency f.

RF-to-baseband receiver architecture

A method and system for reducing local oscillator leakage from radio frequency mixers is disclosed. Compensating circuits are used to reduce or eliminate unwanted leakage from the mixer output signal by controlling the current in individual branches of a balanced input circuit of the mixer. The current is directly controlled by adjusting the voltage on the bases of the differential type amplifier input transistors, or by injecting current directly into the individual branches, or by extracting current directly from the individual branches. The current is also indirectly controlled by increasing the temperature of the mixer components with power dissipation elements that are not connected to the mixer. The compensating circuits are made of different combinations of resistor, transistor and current sink components. By using the compensating circuits with a radio frequency mixer, any DC current differential occurring between two output nodes of the input circuit are reduced or eliminated, resulting in high quality signal transmissions.

Method to reduce local oscillator or carrier leakage in frequency converting mixers

A voltage controlled oscillator has a cross-coupled negative resistance cell formed as an integrated circuit connected to off-chip components of a high-Q resonant tank circuit. To counteract spurious oscillations brought about by package parasitics caused by the interconnection of the chip to the external components, the cell is provided with a degeneration impedance. Typically, a pure inductor is used if all the elements of the tank circuit are off-chip. In a case where the tank circuit includes an on-chip fixed capacitor, the degeneration impedance may take the form of a capacitor.

Voltage controlled oscillator integrated circuit

A tree mixer includes a first differential pair of transistors which divide current from a first current source between the transistors in dependence upon a first differential input signal supplied to first input terminals. Two second differential pairs of transistors have controlled paths which conduct current, divided between the transistors of the differential pair in dependence upon a second differential input signal supplied to second input terminals, dependent upon current passed by a respective transistor of the first pair of transistors, to produce a product signal at output terminals. One or more second current sources provide for the total current passed by the first pair of transistors to be greater than the total current passed by the two second pairs of transistors, for improved linearity without increasing noise. A quadrature phase modulator can include two such mixers with common output circuitry.

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Mountain, Canada

Ronald Douglas Beards