Abstract:
Certain aspects of the present disclosure provide voltage regulating circuits which are power efficient, low noise, and substantially insensitive to changes in process technology, power supply voltage, and temperature. Such circuits may be used to provide the regulated voltage for a voltage-controlled oscillator (VCO), for example, as found in a radio frequency front end (RFFE). One example voltage regulating circuit generally includes a current source configured to supply or sink a reference current and a current mirror having a bias branch and a main branch, wherein the bias branch is connected with the current source, wherein the main branch includes a source follower to provide the regulated voltage, and wherein the reference current is available at a node for the regulated voltage.
Abstract:
Certain aspects of the present disclosure provide methods and apparatus for processing an input signal. One example apparatus is a circuit that generally includes an amplifier, comprising a first transistor and a second transistor connected in cascode with the first transistor; a buffer coupled to an output of the amplifier and configured to provide feedback to the amplifier; and a current source coupled to the second transistor and incorporated into a loop of the feedback to the amplifier.
Abstract:
A multi-band amplifier may operate in a first frequency band and a second frequency band. The multi-band amplifier may include a first amplifier, a second amplifier, and a coupler. The coupler may couple a signal, such as a communication signal, to a selected amplifier. In some embodiments, the coupler may include one or more inductive elements to couple the signal to the first or the second amplifier. In some embodiments, the inductive elements may include a balun.
Abstract:
An apparatus includes a main amplifier configured to receive an input signal. The main amplifier is also configured to generate an output signal. The apparatus also includes an auxiliary path configured to phase-shift the input signal to generate a cancellation signal to reduce or cancel a blocker component of the output signal.
Abstract:
A method and apparatus are disclosed for mitigating a frequency spur included with a transmitter output signal from a wireless device. For at least some embodiments, the wireless device may include an auxiliary synthesizer to generate a spur cancellation signal to be summed with the transmitter output signal to cancel or reduce the frequency spur. The auxiliary synthesizer may also generate an auxiliary clock signal to demodulate a received communication signal. In some embodiments, the transmitter output signal may be looped back to a receiver of the wireless device to determine whether the frequency spur is reduced below a threshold. Data from the receiver may be used to modify the spur cancellation signal.
Abstract:
An oscillator is disclosed that can generate an oscillation signal using a latch and two delay elements. For some embodiments, the oscillator includes an SR latch, a first delay element, and a second delay element. The SR latch has a first input, a second input, a first output, and a second output. The first delay element is coupled between the first output and the first input of the SR latch. The second delay element is coupled between the second output and the second input of the SR latch. For some embodiments, the first and second delay elements include a programmable pull-up circuit that allows the charging current to be adjusted in discrete amounts, and include a programmable capacitor circuit that allows the capacitance value to be adjusted in discrete amounts.