A ramp generator providing ramp signal with high resolution fine gain includes a current mirror having a first and second paths to conduct a capacitor current and an integrator current responsive to the capacitor current. First and second switched capacitor circuits are coupled to the first path. A fractional divider circuit is coupled to receive a clock signal to generate in response to an adjustable fractional divider ratio K a switched capacitor control signal that oscillates between first and second states to control the first and second switched capacitor circuits. The first and second switched capacitor circuits are coupled to be alternatingly charged by the capacitor current and discharged in response to each the switched capacitor control signal. An integrator coupled is to the second path to generate the ramp signal in response to the integrator current.

An example digital to time converter includes: a first switch having a first terminal, a second terminal, and a first control terminal configured to receive a control signal. A second switch having a third terminal coupled to second terminal, a fourth terminal, and a second control terminal configured to receive a divided clock signal. A third switch having a fifth terminal coupled to the second terminal and the third terminal, a sixth terminal, and a third control terminal configured to receive an inverted version of divided clock signal. A fourth switch having a seventh terminal coupled to the second terminal, an eighth terminal, and a fourth control terminal configured to receive an inverted version of control signal. A fifth switch having a ninth terminal coupled to the eighth terminal and a fifth control terminal configured to receive the inverted divided clock signal. A capacitor coupled to the sixth terminal.

The invention provides a system improving signal handling, e.g., transmission and/or processing. In an embodiment, the system may include a filter circuit, a magnitude bit truncation circuit and a utility circuit. The filter circuit may be coupled to a target signal which contains one or more desired signals at one or more interested bands, for attenuating each said interested band to form a filtered signal. The magnitude bit truncation circuit may be coupled to the filter circuit, for truncating one or more bits of each sample of the filtered signal to form a truncated signal. The utility circuit may be coupled to the magnitude bit truncation circuit, for handling the truncated signal to implement handling of the target signal, so as to reduce resource requirement and enhance error tolerance comparing with directly handling the target signal.

Techniques are provided for phase coherent frequency synthesis. An embodiment includes a first phase accumulator to accumulate a frequency control word (FCW) at a clocked rate to produce a first digital phase signal representing phase data corresponding to phase points on a first sinusoidal waveform. The embodiment also includes a second phase accumulator to produce an incrementing reference count at the clocked rate and multiply it by the FCW to produce a second digital phase signal representing phase data corresponding to phase points on a second sinusoidal waveform. The multiplication is performed in response to change in the FCW. The embodiment further includes a multiplexer to select between the first and second digital phase signals based on completion of the multiplication. The embodiment also includes a phase-to-amplitude converter to generate digital amplitude data corresponding to the phase points on a sinusoidal waveform associated with the selected digital phase signal.

An apparatus for mitigating nonlinearity-induced spurs and noise in a fractional-N frequency synthesizer

A digital delta-sigma modulator (DDSM) is disclosed with an input signal x[n], an output signal y[n], a quantization error signal e[n] and a dither signal d[n], having an equation described in the z-domain by

Y(z)=STF(z)X(z)+DTF(z)D(z)−NTF(z)E(z)

wherein Y(z), X(z), D(z) andE(z) are z-transforms of the output signal, the input signal, the dither signal, and the quantization error signal, and wherein STF (z), DTF(z) and NTF(z) correspond to a transfer function of the input signal, a transfer function of the dither signal, and a transfer function of the quantization error signal, and wherein the transfer function of the quantization error signal is of the form:

[00001]$\mathrm{NTF}\left(z\right)={\mathrm{Az}}^{-Q}\left(1-z^{-1}\right)\left(1+\underset{i=1}{\overset{K}{.Math.}}{c}_i{z}^{-i}\right)$

where A , Q and K are constants, coefficients c.sub.i are real valued and c.sub.K≠0 and wherein at least one of the zeroes z.sub.j of

[00002]$\left(1+\underset{i=1}{\overset{K}{.Math.}}{c}_i{z}^{-i}\right)$

satisfies z.sub.j≠+1 for j=1, 2, . . . , K

Systems and methods for a power-efficient 3-level digital-to-analog converter. A converter cell using a current starving technique keeps a portion of the converter cell turned on in a low power mode, as opposed to completely turning off current in selected modes. A conversion system keeps a first set of converters active while allowing a second set of converters to be powered down. Systems and methods presented save power and allow for efficient reactivation of converters.

An instrument configured to process signal data is disclosed. The instrument is operable to control and or change the sampling rate of the signal data from a first sample rate to a second sample rate different than the first sample rate.

A delay chain circuit with series coupled delay elements receives a reference clock signal and outputs phase-shifted clock signals. A multiplexer circuit receives the phase-shifted clock signals and selects among the phase-shifted clock signals for output as in response to a selection signal. The selection signal is generated by a control circuit from a periodic signal having a triangular wave profile. A sigma-delta modulator converts the periodic signal to a digital signal, and an integrator circuit integrates the digital signal to output the selection signal. The selected phase-shifted clock signal is applied as the reference signal to a phase locked loop which generates a spread spectrum clock signal.

A ramp generator providing ramp signal with high resolution fine gain includes a current mirror having a first and second paths to conduct a capacitor current and an integrator current responsive to the capacitor current. First and second switched capacitor circuits are coupled to the first path. A fractional divider circuit is coupled to receive a clock signal to generate in response to an adjustable fractional divider ratio K a switched capacitor control signal that oscillates between first and second states to control the first and second switched capacitor circuits. The first and second switched capacitor circuits are coupled to be alternatingly charged by the capacitor current and discharged in response to each the switched capacitor control signal. An integrator coupled is to the second path to generate the ramp signal in response to the integrator current.

Systems and methods for improving noise efficiency in a Delta Sigma modulator. A bypass scheme for a noise splitter is disclosed that reduces toggling activity for small signals. In particular, a sample-by-sample bypass noise splitter is disclosed that includes a noise splitting module and a bypass line. The bypass line bypasses the noise splitting module when signals are below a selected threshold, increasing efficiency of the system.