Frequency synthesizer circuitry includes multi-phase clock generator circuitry, frequency divider circuitry, signal retiming circuitry, and signal combining circuitry. The multi-phase clock generator circuitry receives an input clock signal and generates a number of multi-phase clock signals. The frequency divider circuitry also receives the input clock signal and performs frequency division thereon to generate a reference signal. The signal retiming circuitry receives the reference signal and the multi-phase clock signals and generates a number of retiming signals. The signal combining circuitry combines two of the retiming signals to provide an output clock signal that has the same frequency as the reference signal but a different duty cycle.

A quadrature clock generating apparatus connected to a local oscillator generating an input clock signal and an inverted input clock signal includes a fractional dividing circuit and a quadrature signal generating circuit. The fractional dividing circuit is configured for receiving the input clock signal and the inverted input clock signal, and for performing frequency-division upon the input clock signal and the inverted input clock signal to generate a frequency-divided clock signal according to a fractional dividing parameter. The quadrature signal generating circuit is configured for receiving the input clock signal, the inverted input clock signal, and the frequency-divided clock signal to generate a plurality of quadrature clock signals.

A semi-digital finite impulse response, FIR, filter is configured as a sparse FIR filter and as a minimum phase lag FIR filter. The FIR filter has a delay line composed of a number of sets of delay units sequentially coupled to each other, and where some of the sets of delay units have one or more untapped delay units as part of a cascade of two or more single-sample delay units. An analog summing node is coupled to the taps and produces at its output an analog version of a digital input signal that is fed to an input of the delay line. Other embodiments are also described and claimed.

The data serialization circuit includes a delay circuit, a data serializer, a first data sampler and a second data sampler. The delay circuit receives an input clock signal and generates a plurality of delayed clock signals. The delayed clock signals includes a first delayed clock signal generated by a first delay stage and a second delayed clock signal generated by a second delay stage. The data serializer receives parallel data and a final stage delayed clock signal of the delayed clock signals, and converts the parallel data into serial data according to the final stage delayed clock signal. Wherein, the first data sampler samples the serial data according to the first delayed clock signal to generate a first output serial data, and the second data sampler samples the first output serial data according to the second delayed clock signal to generate a second output serial data.

An envelope tracking scheme can be used, such as to modulate a supply node of a power amplifier circuit to improve efficiency. For example, a magnitude or amplitude envelope of a signal to be modulated can be scaled and used to drive a node, such as a drain, of the power amplifier circuit. An envelope tracking signal can be generated such as having a bandwidth that is compressed as compared to a full-bandwidth envelope signal. A peak-value look ahead technique can be used, for example, so that amplitude compression or clipping of the transmit signal is suppressed when the bandwidth-compressed envelope tracking signal is used to modulate a supply node of the power amplifier used to amplify the transmit signal.

A method and device for generating a multi-rate clock signal using a ring voltage-controlled oscillator based phase-locked loop is provided. The device includes a delay line having a length extending beyond a predetermined length required for operation of the phase-locked loop. The device further includes a tap tuning logic circuit coupled to the delay line. The delay line receives an input signal and a tuning voltage from the phase frequency detector, charge pump and loop filter circuits and generates a plurality of tapped output signals. The plurality of tapped output signals is received by the integrated digital multi-rate clock generator configured to create a plurality of clock signals.

A circuit for estimating a time difference between a first signal and a second signal, the circuit comprising: a first signal line for receiving the first signal; a delay unit configured to receive the second signal and delay the second signal so as to provide a plurality of delayed versions of the second signal, each delayed version being delayed by a different amount of delay to the other delayed versions; a comparison unit configured to compare each of the delayed versions of the second signal with the first signal so as to identify which of the delayed versions of the second signal is the closest temporally matching signal to the first signal; and a difference estimator configured to estimate the time difference between the first and second signals in dependence on the identified delayed version.

A circuit for generating clock signals enabling the latching of data is described. The circuit comprises a pulse generator coupled to receive an input clock signal at an input and to generate an output clock signal at an output; a latch circuit coupled to receive the output clock signal; and a pulse shaping circuit coupled to receive a feedback signal; wherein a pulse width of the output clock signal is determined by the feedback signal and the input signal coupled to the pulse generator. A method of generating clock signals enabling the latching of data is also described.

A circuit for estimating a time difference between a first signal and a second signal includes a first signal line for receiving the first signal; a delay unit configured to receive the second signal and delay the second signal so as to provide a plurality of delayed versions of the second signal, each delayed version being delayed by a different amount of delay to the other delayed versions; a comparison unit configured to compare each of the delayed versions of the second signal with the first signal so as to identify which of the delayed versions of the second signal is the closest temporally matching signal to the first signal; and a difference estimator configured to estimate the time difference between the first and second signals in dependence on the identified delayed version.

A time difference between an occurrence of a first event and an occurrence of a second event is estimated. A first time marker indicating the occurrence of the first event and a second time marker indicating the occurrence of the second event are received, wherein at least one event is one of playing a media frame or receiving a beacon. A plurality of delayed versions of the first time marker are provided, each being delayed by a different amount of delay to the other delayed versions. Each of the delayed versions of the first time marker are compared with the second time marker to identify which of the delayed versions of the first time marker is the closest temporally matching time marker to the second time marker. The time difference between the first and second time markers is estimated in dependence on the identified delayed version.