Abstract:
A novel and useful look-ahead time to digital converter (TDC) that is applied to an all digital phase locked loop (ADPLL) as the fractional phase error detector. The deterministic nature of the phase error during frequency/phase lock is exploited to achieve a reduction in power consumption of the TDC. The look-ahead TDC circuit is used to construct a cyclic DTC-TDC pair which functions to reduce fractional spurs of the output spectrum in near-integer channels by randomly rotating the cyclic DTC-TDC structure so that it starts from a different point every reference clock thereby averaging out the mismatch of the elements. Associated rotation and dithering methods are also presented. The ADPLL is achieved using the look-ahead TDC and/or cyclic DTC-TDC pair circuit.
Abstract:
A novel and useful 60 GHz frequency generator based on a third harmonic extraction technique which improves system level efficiency and performance. The frequency generator employs a third harmonic boosting technique to increase the third harmonic at the output of the oscillator. The oscillator generates both ˜20 GHz fundamental and a significant amount of the third harmonic at ˜60 GHz and avoids the need for a frequency divider operating at 60 GHz. The undesired fundamental harmonic at ˜20 GHz is rejected by the good fundamental HRR inherent in the oscillator buffer stage while the ˜60 GHz component is amplified to the output. The fundamental harmonic is further suppressed by an active cancellation by properly combining the two outputs. The oscillator fabricated in 40 nm CMOS exhibits a phase noise of −100 dBc/Hz at 1 MHz offset from a 60 GHz carrier and have a tuning range of 25%.
Abstract:
A novel and useful LC-tank digitally controlled oscillator (DCO) incorporating a split transformer configuration. The LC-tank oscillator exhibits a significant reduction in area such that it is comparable in size to conventional ring oscillators (ROs) while still retaining its salient features of excellent phase noise and low sensitivity to supply variations. The oscillator incorporates an ultra-compact split transformer topology that is less susceptible to common-mode electromagnetic interference than regular high-Q LC tanks which is highly desirable in SoC environments. The oscillator, together with a novel dc-coupled buffer, can be incorporated within a wide range of circuit applications, including clock generators and an all-digital phase-locked loop (ADPLL) intended for wireline applications.
Abstract:
A time-to-digital system, such as a frequency synthesizer, includes a power management circuit and a time-to-digital converter (TDC). Said power management circuit is coupled to a frequency reference clock and a variable clock, and arranged to output a delayed frequency reference clock and a single pulse of said variable clock ahead of a transition of said delayed frequency reference clock. Said TDC is coupled to said power management circuit and arranged to produce a digital TDC output.
Abstract:
A method of estimating gain of a time-to-digital converter (TDC) includes: capturing a TDC output sample; calculating a gradient in response to the TDC output sample; and adjusting a TDC normalizing gain based on the calculating step. Another method of calibrating gain of a TDC includes: capturing a phase error which is derived from a TDC output sample, a reference phase and a variable phase; calculating a gradient in response to the phase error; and adjusting a TDC normalizing gain based on the calculating step.
Abstract:
A frequency modulating path for generating a frequency modulated clock includes a direct feed input arranged for directly modulating frequency of an oscillator, and a compensating feed input arranged for compensating effects of frequency modulating on a phase error; wherein the compensating feed input is resampled by a down-divided clock that is an integer edge division of the oscillator. A reference phase generator for generating a reference phase output includes a resampling circuit, an accumulator and a sampler. The resampling circuit is for resampling a modulating frequency command word (FCW) input to produce a plurality of samples. The accumulator is for accumulating the samples to generate an accumulated result. The sampler is for sampling the accumulated result according to a frequency reference clock, and accordingly generating a sampled result, wherein the reference phase output is updated according to at least the sampled result.
Abstract:
One clock generator includes an oscillator block, a delay circuit, and an output block. The oscillator block provides a first clock of multiple phases. The delay circuit delays at least one of said multiple phases of said first clock to generate a second clock of multiple phases. The output block generates a third clock by selecting signals from said multiple phases of said second clock, wherein said third clock has non-harmonic relationship with said first clock. Another exemplary clock generator includes an oscillator block and an output block. The oscillator block includes an oscillator arranged to provide a first clock, and a delay locked loop arranged to generate a second clock according to said first clock. The output block generates a third clock by selecting signals from said multiple phases, wherein said third clock has non-harmonic relationship with said first clock.
Abstract:
A frequency synthesizer includes an oscillator for providing an RF clock, a phase shifter coupled to said oscillator for providing a shifted RF clock by changing phase of said RF clock, and a time-to-digital converter (TDC) coupled to said phase shifter for quantizing a time difference between a frequency reference clock and said shifted RF clock, wherein a range of said TDC covers significantly less than a full range of said RF clock period. An associated method is also provided.
Abstract:
Methods to implement low cost, high efficiency, low loss power combiner with novel matching circuits are disclosed. A narrow band power combiner enables a high power and high efficiency radio frequency power amplifier to be realized using multiple low voltage CMOS transistors or micro power amplifiers. The power combiner may be printed on a package substrate and realized either using single layer substrate through edge coupling or multiple layers substrate through broadside coupling. The micro power amplifiers may be fabricated using low voltage CMOS technology and electrical connections between the outputs from the micro power amplifiers and the power combiner may be provided through stud bumps in a flip chip technology. With the tunable matching circuits, the present invention allows the narrow band power combiner to be tuned to different frequencies.
Abstract:
An embodiment of the present invention provides transmitter having a phase locked loop that has a dynamically controllable loop bandwidth. A transmit modulator is coupled to the PLL for performing vector modulation in response to transmission symbols. Each transmission symbol comprises an amplitude signal and a phase signal. A controller is coupled to the PLL and to the transmit modulator and is operable to detect when a criteria of the transmission symbols crosses a threshold and to adjust loop bandwidth in response to crossing the threshold. The criteria of the transmission symbols may be a function of the amplitude signal or a function of the phase signal, and may be the amplitude signal, a first derivative of the amplitude signal, a second derivative of the amplitude signal, a square of the amplitude signal, a derivative of the amplitude signal squared, the phase signal, or a derivative of the phase signal.