Vecima Networks Inc.

Vcom Inc.

Surinder Kumar

Gerald Harron

Jason T Tucker

Gregory Clayton Whittet

Sumit Kumar

Douglas Fast

A method is provided for reducing inter modulation distortion products using multi-carrier phase alignment of the type where a combined carrier signal is generated from the combined output carried waves of a plurality of numerically controlled oscillators in which the frequency of the carrier wave can be altered by changing an input value into the oscillator. In particular the initial phase of the output carrier waves is adjusted so that the peak amplitude of the combined carrier signal is minimized so that compression of the higher amplitude portions of the combined signal is reduced.

Method for reducing inter modulation distortion products of a combined carrier wave using phase alignment of the carrier components

Direct digital QAM modulation at an RF frequency is obtained from digitally synthesized RF signals which are generated for use as the two vectors. The two vectors are individually controlled in phase and summed to provide a combined phase and amplitude modulation that forms the modulated signal. The synthesized RF signal is generated from a higher reference frequency using a variable pulse stretching technique implemented with programmable delay lines. The amount of the pulse stretch in each cycle is controlled by a phase increment value. Pulse stretching can be extended beyond one cycle by pulse swallowing, allowing the generation of an RF signal from DC up to and including the input reference frequency. Phase modulation is added by digital control of the pulse stretching according to the phase modulation data bits.

Method and apparatus for digital vector QAM modulator

A method to improve the frequency resolution and phase noise of a synthesized RF signal results in superior instantaneous frequency change and phase modulation capability, wide frequency set ability, and suitability for implementation in a digital ASIC. The RF signal synthesis is achieved from a higher reference frequency clock signal using a variable pulse stretching technique. The amount of the pulse stretch in each cycle is set by a phase increment value and is implemented using programmable delay lines. Pulse stretching can be extended beyond one cycle by pulse swallowing, allowing the generation of an RF signal with frequencies from DC up to the input reference frequency. Phase modulation is incorporated by digital control of the phase stretching with the phase modulation bits.

Apparatus for fractional RF signal synthesis with phase modulation

A time-sliced discrete-time Phase Locked Loop which is suitable for simultaneously synchronizing multiple input signals to multiple output signals is provided by implementing a discrete-time phase detector, loop filter, and voltage controlled oscillator that together operate as a single discrete-time PLL in hardware and applying control logic to retrieve the history for each signal pair from a context memory (RAM), to enable the discrete-time PLL hardware, and to store the resulting history in the context memory for use in subsequent operations for a particular input/output signal pair.

Timesliced discrete-time phase locked loop

The present invention provides a method to improve the frequency resolution and phase noise of a synthesized RF signal. It also results in the superior characteristics of instantaneous frequency changeability, wide frequency setting ability, and fully digital ASIC implementation ability. The synthesized RF signal is generated from a higher reference frequency using a variable pulse stretching technique. The amount of the pulse stretch in each cycle is controlled by a phase increment value and is implemented using programmable delay lines. Pulse stretching is extended beyond one cycle by pulse swallowing, allowing the generation of an RF signal from DC up to the input reference clock signal frequency.

Method and apparatus for fractional RF signal synthesis

The present invention provides a means to implement amplitude and phase modulation digitally and directly at an RF frequency that benefits from high output power without the use of amplifiers. This is accomplished by the combination of two varying amplitude and phase vectors. A reference oscillator produces a carrier signal, which is supplied to two digital delay lines composed of a sequence of delay banks. The delay lines are controlled by lookup tables that are updated by the vector control circuit, used to determine the delay of each digital delay line. The output of each delay line is multiplexed to a switching bank which is also controlled by the vector control circuit. The output of the switching bank, in combination with a summer, is used to produce discrete amplitude adjustment of the vector. The delay of the lines and the summation adjustment are set in such a way as to produce two vectors with the desired phase shift and magnitude the summation of these two vectors produces a resultant vector with the desired phase and amplitude characteristics.

Modulation using discrete amplitude adjustment and dual digital delay lines

The present invention provides a means to implement amplitude and phase modulation digitally and directly at an RF frequency that benefits from high output power using non-linear amplifiers. This is accomplished by the combination of two constant amplitude phase varying vectors. A reference oscillator produces a carrier signal, which is supplied to two digital delay lines composed of a sequence of delay banks. The delay lines are controlled by lookup tables that are updated by the vector control circuit used to determine the delay of each digital delay line. The delay of the lines are set in such a way as to produce two vectors with the desired phase shift that, when summed together, produce a vector with the desired phase and amplitude characteristics.

Growing community of inventors

Victoria, Canada

Surinder Kumar