Abstract:
Selectively enabling an amplitude processing circuit and a phase processing circuit of a wireless station's polar receiver with respect to reception of a beacon signal. Such systems and methods may include sequentially demodulating symbols of the received beacon signal using at least the phase processing circuit to detect a traffic indication signal value in a data payload portion of the received beacon signal. Upon detecting a condition indicating no data traffic for the wireless station, the phase processing circuit may be turned off. The polar receiver may demodulate symbols of the received beacon signal and upon detecting a beacon preamble symbol sequence, shut off the amplitude processing circuit and set the amplitude to a fixed value. The phase processing circuit in conjunction with the fixed amplitude value may be used to demodulate symbols of the beacon signal.
Abstract:
A polar transmitter including a digital power amplifier cell that includes a first circuit and an amplifier circuit. The first circuit is configured to receive a phase modulated carrier signal and to generate a PMOS control signal and an NMOS control signal such that the PMOS control signal and the NMOS control signal have different duty cycles. The amplifier circuit is configured to receive the PMOS control signal at a PMOS transistor and the NMOS control signal at an NMOS transistor. The first circuit is configured to align the PMOS control signal and the NMOS control signal with respect to one another such that a time that the NMOS transistor and the PMOS transistor of the amplifier circuit are simultaneously conducting is minimized. The amplifier circuit is configured to generate an amplified modulated carrier signal in response to the PMOS and NMOS control signals.
Abstract:
A predistortion circuit receives an input polar signal to be transmitted, including an input amplitude signal and an input phase signal. The input polar signal is predistorted using at least one predistortion parameter selected from a lookup table. A phase-and-amplitude modulated radio-frequency signal is generated corresponding to the predistorted polar signal. A copy of the generated radio-frequency signal is provided to a polar receiver. The polar receiver is operated to generate, from the copy of the radio-frequency signal and without information relating to the generated transmit signal, a feedback polar signal including a feedback amplitude signal and a feedback phase signal. The feedback polar signal is compared to the input polar signal, the lookup table is updated in response to the comparison.
Abstract:
Wideband polar receivers and method of operation are described. A phase-modulated input signal is received at a polar receiver that includes an injection-locked oscillator. The injection-locked oscillator includes a plurality of injection points. Based on the frequency of the input signal, a particular Nth harmonic is selected, and the input signal is injected at the set of injection points corresponding to the selected Nth harmonic. The injection-locked oscillator generates an oscillator output signal, and the phase of the input signal is determined from the phase of the oscillator output signal. In some embodiments, the oscillator output signal is frequency-multiplied by N, mixed with the input signal, and filtered for use in amplitude detection. The input signal is decoded based on the phase and amplitude information.
Abstract:
Wideband polar receivers and method of operation are described. A phase-modulated input signal is received at a polar receiver that includes an injection-locked oscillator. The injection-locked oscillator includes a plurality of injection points. Based on the frequency of the input signal, a particular Nth harmonic is selected, and the input signal is injected at the set of injection points corresponding to the selected Nth harmonic. The injection-locked oscillator generates an oscillator output signal, and the phase of the input signal is determined from the phase of the oscillator output signal. In some embodiments, the oscillator output signal is frequency-multiplied by N, mixed with the input signal, and filtered for use in amplitude detection. The input signal is decoded based on the phase and amplitude information.
Abstract:
A DAC using current mirrors suitable for use in a modulator. Embodiments include a current-generating circuit to provide an information signal; a bias current source; a current mirror having a mirror input transistor connected to the current generating circuit and the bias current source, and being driven by the bias current and the varying current signal and having a corresponding varying voltage signal at a control terminal; a signal shaping filter interposed between the mirror input transistor and an output mirror transistor configured to limit a bandwidth of the varying voltage signal; the output mirror transistor configured to generate a band-limited varying current signal and a mirrored bias current; and, a mirrored bias current reduction circuit connected to the output mirror transistor configured to reduce the mirrored bias current.
Abstract:
A method of generating inphase and quadrature signals from a polar receiver providing a phase derivative signal and an envelope magnitude signal comprising receiving an estimated phase derivative signal; generating an estimated phase signal; mapping the estimated phase signal to an angular value; converting the estimated phase signal to an inphase signal and a quadrature signal based on the angular value; and, providing the inphase signal and quadrature signal to a demodulation circuit.
Abstract:
A low noise amplifier including a variable gain amplifier stage configured to accept an input signal and to provide a load driving signal; a tunable bandpass filter connected as a load to the variable gain amplifier stage, wherein the bandpass filter includes a cross-coupled transistor pair, and at least one cross-coupled compensation transistor pair biased in a subthreshold region configured to add a transconductance component when the load driving signal is of a magnitude large enough to decreases a transconductance of the cross-coupled transistor pair; and, a controller circuit configured to tune the bandpass filter. The filter can be tuned in respect to the frequency and the quality factor Q.