Rf Micro Devices, Inc.

Motorola Corporation

Alex Wayne Hietala

Scott R Humphreys

Nadim Khlat

Behrooz L Abdi

David M Gonzalez

Patrick Clement

Digital I and Q (NRZ) data streams are generated by specially configured conversion circuits, the outputs of which are applied to a F-N synthesizer to modulate the synthesizer. All illustrative conversion circuit employs a system of comparators to detect the state of analog I and Q signals at each bit interval and to decode outputs of such comparators to determine the NRZ sequence that gave rise to detected states. Once so determined, these NRZ signals are applied to an F-N synthesizer in the same manner as NRZ signals. Advantageously, inputs to present inventive embodiments may be received either as analog or digital I and Q inputs, subject to selection between input modes using only a single binary input.

Fractional-N digital modulation with analog IQ interface

A fractional sequence generator for use in a F-N synthesizer includes a multi-accumulator structure providing a plurality of carry-out signals for application to an adder through a recombination network to generate an output fractional sequence, S, having an average value given by avg(S)&equals;C/D, where C/D is the desired fractional part of the divisor, and denominator, D, is programmable. Illustratively, contents of a n-bit accumulator in each accumulator is augmented by a function of the programmable denominator value upon a carry-out of the associated n-bit adder in that accumulator.

Accumulator with programmable full-scale range

A fractional sequence generator having a plurality of cascaded accumulators whose carry-outs-upon-overflow are provided over a plurality of recombination paths and selective delays to an adder, the pattern of selective delays being modified by the addition of delay elements in all recombination paths except the last to reduce the number of quantization error terms in the transfer function of the sequence generator. Illustrative embodiments may have any number (greater than one) of accumulators and recombination paths, while continuing to exhibit desired simplified frequency response characteristics.

Fractional-N synthesizer with improved noise performance

Apparatus for receiving a carrier signal modulated by a wanted signal, the modulated carrier signal occupying one of a plurality of channels whose central frequencies are separated from one another by a fixed frequency referred to as the channel spacing, the apparatus including a local oscillator for generating first and second signals at a frequency which is not an integral multiple of half the channel spacing whereby when the received carrier signal is mixed with the first and second signals, a complex, digital Very Low Intermediate Frequency (VLIF) signal is generated in which the wanted signal is centred about a VLIF which is slightly larger than half the channel spacing.

Method and apparatus for receiving a signal

A communication device (100) employs a local oscillator (104) having an improved charge pump circuit (122). The charge pump circuit (122) has current mirrors (204, 208) in which a first transistor (224, 270) is biased to provide a substantially constant current. A resistor (226, 272) selectively conducts a reference current to bias a mirror transistor (228, 274). The current mirror (204, 208) provides improved dynamic performance thereby reducing global phase error of the communication device (100).

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Phoenix, AZ, United States of America

Alex Wayne Hietala