Abstract:
Described is an apparatus which comprises: a pre-driver coupled to a transmitter, the transmitter having a differential output; and a tuning circuit operable to couple to the differential output to tune the pre-driver of the transmitter according to a common mode noise signature of a common mode signal derived from the differential output.
Abstract:
An apparatus (1000) and method for sensing load current of an envelope tracking (ET) modulator (1150) enables load impedance of a power amplifier (130) to be measured. Impairments associated with the load impedance characteristic can be suppressed by calibration and pre-distortion instead of by feedback. The ET modulator (1150) provides a switching regulator that can be reconfigured as a linear regulator for the purpose of sensing the load current. This allows the ET modulator (1150) to be operated open-loop, thereby eliminating the power consumption overhead resulting from utilization of a loop filter and error amplifier and achieving a higher overall efficiency.
Abstract:
A communication system (20) includes a transmitter (22) having a peak controller (38) which controls PAPR to operate in accordance with a noise constraint. A backoff controller (60) operates in conjunction with an amplifier section (46) to cause the amplifier section (46) to maximize the amplification it applies while maintaining a predetermined degree of amplifier linearity. The noise constraint is provided by an equilibrium estimator (64) that provides a noise target parameter (66) to the peak controller (38). The noise target parameter (66) is configured to identify the transmitter's equilibrium point (126). The equilibrium point (126) is that signal-to-noise ratio (SNR) for the signal (26) broadcast from the transmitter (22) where a demodulator (118) in a receiver (24) will experience a reduced SNR if the transmitted signal (26) SNR either increases or decreases.
Abstract:
An RF transmitter (60) generates non-DC bias signals (104, 106) configured to improved power-added efficiency (PAE) in the operation of an RF amplifier (94). The RF amplifier (94) generates an amplified RF signal (126) which, due to the addition of the bias signals (104, 106), includes bias-signal-induced RF distortion (48, 50). The bias signals (104, 106) drive a bias- induced distortion cancellation circuit (152) that adjusts the bias signals to compensate for the influence of impedances experienced by the bias signals (104, 106) before being applied to the RF amplifier (94). After mixing with a signal (64, 71) responsive to a baseband communication signal (64), adjusted bias signals (186, 188) are combined into a composite baseband signal (76), upconverted to RF in an upconversion section 84, and applied to the RF amplifier (94) where they cancel at least a portion of the bias-signal-induced RF distortion (48, 50).
Abstract:
A transmitter is provided with a local oscillator (LO) processing unit to maintain stability in the transmitter's feedback loop. The LO processing unit includes at least one delay locked loop (DLL) and a programmable divider to generate phase shifted LO signals for adjusting a loop phase of the feedback loop in the transmitter. The generated phase shifted LO signals are of both a coarse and fine phase shifted nature. The adjustability and control of the coarse and fine phase shifting of the LO signals maintains linearity in the transmitter feedback loop.