Analog Devices,inc.

Mediatek Corporation

Edmund J Balboni

Colm J Prendergast

Daniel E Fague

Thomas J Liptay

Marc E Goldfarb

Phillip M Sher

Sriram Krishnan

Jeffrey R Feigin

Jonathan Richard Strange

Robert J Broughton

Wyn T Palmer

Benjamin P Walker

Apparatus and methods for switch-coupled oscillators are disclosed. In certain implementations, an oscillator system includes a primary oscillator, one or more auxiliary oscillators, one or more switching circuits, and an oscillator control circuit. The oscillator control circuit can be used to control the one or more switching circuits to selectively couple the primary oscillator to all or a portion of the one or more auxiliary oscillators. The oscillator control circuit can also disable any auxiliary oscillators that are decoupled from the primary oscillator to reduce power consumption. By selecting a number of auxiliary oscillators to couple to the primary oscillator, the oscillator system can have a configurable phase noise versus power consumption profile.

Apparatus and methods for switch-coupled oscillators

Apparatus and methods provide a differential current buffer. The current buffer has cross-coupled feedback and offers relatively good common-mode rejection and a relatively low and linear input impedance, which can reduce intermodulation distortion. The current buffer can be used in, for example, an RF modulator, such as a quadrature modulator.

Differential current buffer

A radio frequency (RF) receiver having an analog gain control section for controlling the gain of a received RF signal, and a digital demodulator section for demodulating the output of the gain control section, includes an analog GO circuit connected to recognize the presence of a data packet within a received RF signal in the analog gain control section, and in response to produce an analog GO signal, a digital GO circuit connected to recognize the presence of a data packet within the received RF signal from the digital demodulator section, and in response to produce a digital GO signal, and control circuitry connected to enable gain control functions within the analog gain control section and digital demodulator functions within the digital demodulator section in response to respective analog and digital GO signals.

Apparatus and method for RF packet detection and symbol timing recovery

Apparatus and methods are disclosed, such as those involving a transconductance amplifier. One such apparatus includes a transconductance amplifier comprising an input to receive an input voltage signal, and an output to provide an output current signal at least partly in response to the input voltage signal. The apparatus also includes a linearizer configured to remove non-linearity in the output current signal such that the output current signal is substantially linear when the input voltage signal is within a range; and a current booster configured to add a current to the output current signal such that the output current signal is substantially linear when the input voltage signal is outside the range. The current booster allows the amplifier to have a linear response to a larger voltage swing without adding noise.

Apparatus and method for providing linear transconductance amplification

Disclosed are apparatus and methods for electronic signal conversion in which a power level of the signal is used to adjust the bias current of a converter.

Adaptive bias circuit

A device for amplifying signals over a wide frequency range features stacked amplifying modules connected between a DC voltage source and an electrical ground. The stacking configuration reuses the DC current produced the voltage source, and thus reduces the amount of operational DC current permitting the use of lower voltage, higher frequency devices to be used. The amplifying modules are fed signals which are different versions of an input signal, and the output signals are AC coupled using capacitors to balance out gain imbalances and asymmetries between the amplifying modules.

Wideband RF amplifiers

A dynamically self-bootstrapping circuit for a switch features a resistor in series with the control node of the switch. A bypass switch connects a control node to ground. When the switch is in an off-state, the bypass switch is enabled.

Method and apparatus for a dynamically self-bootstrapped switch

An RF receiver includes an analog GO circuit that recognizes the presence of a data packet within a received RF signal in the receiver's analog gain control section, and in response produces an analog GO signal, and a digital GO circuit that recognizes the presence of a data packet from the receiver's digital demodulator section, and in response produces a digital GO signal. Gain control functions within the analog gain control section, and digital demodulator functions within the digital demodulator section, are enabled in response to respective analog and digital GO signals. The system is capable of distinguishing a valid data packet from noise, co-channel interference and adjacent panel interference. A symbol timing recovery circuit within the receiver identifies periodic samples of a data packet preamble that most closely match the preamble bits, with the receiver employing a continuation of the identified periodic samples to decode the remainder of the data packet.

A phase-locked loop frequency synthesizer has a charge pump, phase-locked loop filter, voltage-controlled oscillator, and a bandwidth calibration circuit. The bandwidth calibration circuit measures the gain of the voltage-controlled oscillator and uses the measured voltage-controlled oscillator gain to adjust the charge pump level. The charge pump level is adjusted so that a product of the voltage-controlled oscillator gain and the measured charge pump level results in a constant phase-locked loop bandwidth.

Phase-locked loop bandwidth calibration circuit and method thereof

Frequency offsets between a received carrier signal and a receiver's LO frequency are compensated by determining the offset and adjusting the phase of a demodulated signal derived from the modulated carrier. For frequency offsets that produce DC voltage offsets in I and Q components of the demodulated signal, the phase correction is implemented by operating upon the I and Q components with phase rotation operators in the form of sin &#x3b8; and cos &#x3b8;, where &#x3b8; is an angle whose tangent is the result of dividing the Q by the I frequency offsets.

Method and apparatus for frequency offset compensation

Reference signal generators are provided that automatically adjusts a reference signal's amplitude when that signal is delivered into system loads having unknown capacitances. The amplitude is preferably initiated at a maximum amplitude to insure operation of system elements that require the reference signal. It is subsequently adjusted downward to a controlled reference amplitude which is predetermined to be an amplitude sufficient to sustain proper operation of the system elements but sufficiently reduced to minimize the spurious signals typically generated by fast high-level current transitions. In addition, the reduction to the controlled amplitude reduces the system current drain. The level control is realized in a buffer amplifier so that the amplitude level of an oscillator signal can be set independently to maximize its signal-to-noise performance. Accordingly, requirements for the reference amplitude do not compromise requirements for the amplitude level of the oscillator signal.

Reference signal generators

A wideband impedance attenuator includes a phase-locked loop filter, a voltage-controlled oscillator connected to the phase-locked loop filter during transmit, and an impedance circuit connected to the phase-locked loop filter and the voltage controlled oscillator. The impedance circuit is a scaled version of the phase-locked loop filter. Moreover, the wideband impedance attenuator attenuates a Gaussian frequency shift key modulation signal by a factor of 1/(N+1) using the impedance circuit, which has an impedance of N*Z(s), and the phase-locked loop filter, which has an impedance of Z(s). An output frequency is generated using a voltage-controlled oscillator wherein the output frequency corresponds to the attenuated Gaussian frequency shift key modulation signal. In addition, a comparator compares a voltage of an output from the programmable gain amplifier with a voltage necessary to produce a predetermined frequency shift in a voltage-controlled oscillator to produce a gain signal. A gain controller, in response to the gain signal produced by the comparator, controls a gain of the programmable gain amplifier.

Phase-locked loop filter with out of band rejection in low bandwidth mode

A direct conversion receiver apparatus includes a local oscillator to produce a first local oscillation signal and a second oscillation signal. A first modulation circuit modulates the first local oscillation signal, and a second modulation circuit modulates the second local oscillation signal. A RF mixer mixes a received radio frequency signal with the modulated first local oscillation signal, and another RF mixer mixes the received radio frequency signal with the modulated second local oscillation signal. Demodulating circuits translate desired signals of the mixed signal from the RF mixers into band and translate undesired signals of the mixed signal out of band. Filters remove the undesired signals from the demodulated signals.

Direct conversion receiver apparatus

Wideband modulation summing network and method thereof

A wideband impedance attenuator includes a phase-locked loop filter, a voltage-controlled oscillator connected to the phase-locked loop filter during transmit, and an impedance circuit connected to the phase-locked loop filter and the voltage controlled oscillator. The impedance circuit is a scaled version of the phase-locked loop filter. Moreover, the wideband impedance attenuator attenuates a Gaussian frequency shift key modulation signal by a factor of 1/(N&plus;1) using the impedance circuit, which has an impedance of N*Z(s), and the phase-locked loop filter, which has an impedance of Z(s). An output frequency is generated using a voltage-controlled oscillator wherein the output frequency corresponds to the attenuated Gaussian frequency shift key modulation signal. In addition, a comparator compares a voltage of an output from the programmable gain amplifier with a voltage necessary to produce a predetermined frequency shift in a voltage-controlled oscillator to produce a gain signal. A gain controller, in response to the gain signal produced by the comparator, controls a gain of the programmable gain amplifier.

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Littleton, MA, United States of America

Edmund J Balboni