An amplifier for a receiver circuit is disclosed. The amplifier has an input node (V.sub.in) and an output node (V.sub.out). It comprises a tunable tank circuit connected to the output node (V.sub.out), a feedback circuit path connected between the output node (V.sub.out) and the input node (V.sub.in), and a tunable capacitor connected between an internal node of the feedback circuit path and a reference-voltage node. A receiver circuit and a communication apparatus is disclosed as well.

To provide a radio-frequency module and a communication apparatus that are capable of suppressing degradation in filter characteristics while reducing the sizes of the radio-frequency module and the communication apparatus. A radio-frequency module (1) includes a common terminal, a first filter (21), a second filter (22), a mounting substrate (3), and an external connection terminal (8a). The first filter (21) is connected to the common terminal and transmits a first signal in a first frequency band. The second filter (22) is connected to the common terminal and transmits a second signal in a second frequency band. The mounting substrate (3) has the first filter (21) mounted thereon. The first filter (21) is connected to the mounting substrate (3) with the external connection terminal (8a). The second filter (22) is laminated on the first filter (21). The external connection terminal (8a) is the common terminal.

A circuit includes a radio frequency (RF) channel including an input node and an output node and being configured to receive an RF oscillator signal at the input node and to provide an RF output signal at the output node; a mixer configured to mix an RF reference signal and an RF test signal representative of the RF output signal to generate a mixer output signal; an analog-to-digital converter configured to sample the mixer output signal in order to provide a sequence of sampled values; and a control circuit configured to provide a sequence of phase offsets by phase-shifting at least one of the RF test signal and the RF reference signal using one or more phase shifters, calculate a spectral value from the sequence of sampled values; and calculate estimated phase information indicating a phase of the RF output signal based on the spectral value.

Described herein is an implantable medical device (IMD) that wirelessly communicates another IMD, and methods for use therewith. Such a method can include receiving one or more implant-to-implant (i2i) communication signals from the other IMD using a communication receiver of the IMD, measuring a strength of at least one of the one or more received i2i communication signals or a surrogate thereof, and updating a strength metric based on the measured strength or surrogate thereof. The method further includes determining, based on the updated strength metric, whether to increase, decrease, or maintain the sensitivity of the communication receiver of the IMD, and responding accordingly such that the sensitivity is sometimes increased, sometimes decreased, and sometimes maintained. The method can also include selectively causing a transmitter of the IMD to transmit an i2i communication signal to the other IMD requesting that the other IMD adjust its transmission strength.

A circuit is described herein. In accordance with one embodiment the circuit includes two or more RF channels, wherein each channel includes an input node, a phase shifter and an output node. Each channel is configured to receive an RF oscillator signal at the input node and to provide an RF output signal at the output node. The circuit further includes an RF combiner circuit that is coupled with the outputs of the RF channels and configured to generate a combined signal representing a combination of the RF output signals, and a monitor circuit that includes a mixer and is configured to receive and down-convert the combined signal using an RF reference signal. Thus a mixer output signal is generated that depends on the phases of the RF output signals.

There are provided an oscillator circuit and a radio receiver capable of reducing a frequency fluctuation of an oscillation frequency to a small extent. There is provided an oscillator circuit including an LC oscillator circuit, an amplitude detection circuit, and a bias generation circuit, in which the LC oscillator circuit includes an inductor and at least one variable capacitance element, the amplitude detection circuit detects an oscillation amplitude of the LC oscillator circuit and converts the oscillation amplitude into a DC voltage, and the bias generation circuit compares the DC voltage with a voltage for generating a bias signal, the voltage changing on the basis of a temperature fluctuation of the bias generation circuit, calculates a difference between the DC voltage and a voltage after the change, and generates, on the basis of the difference, a bias signal that reduces a fluctuation in the oscillation amplitude, to control the oscillation amplitude.

A transmitter device includes a transmitter including a first oscillator circuitry, a signal processing circuitry, and a calibration circuitry, and a second oscillator circuitry. The first oscillator circuitry is configured to output a first oscillating signal. The signal processing circuitry is configured to mix calibration signals according to the first oscillating signal, in order to emit a first output signal. The calibration circuitry is configured to detect a power of the first output signal to generate coefficients, and generate the calibration signals according to the coefficients, an in-phase data signal, and a quadrature data signal. The second oscillator circuitry is disposed adjacent to the transmitter, and is configured to output a second oscillating signal. The calibration signals are configured to reduce a pulling generated by both of the first output signal and the second oscillating signal to the first oscillator circuitry.

In tuning a radio frequency (RF) module including a non-volatile tunable RF filter, a desired frequency and an undesired frequency being provided by an amplifier of the RF module are detected. The non-volatile tunable RF filter is coupled to an output of the amplifier of the RF module. A factory setting of an adjustable capacitor in the non-volatile tunable RF filter is changed by factory-setting a state of a non-volatile RF switch, such that the non-volatile tunable RF filter substantially rejects the undesired frequency and substantially passes the desired frequency. The adjustable capacitor includes the non-volatile RF switch, and the factory setting of the adjustable capacitor corresponds to a factory-set state of the non-volatile RF switch. An end-user is prevented access to the non-volatile RF switch, so as prevent the end-user from modifying the factory-set state of the non-volatile RF switch.

A tunable filter is described where the frequency response as well as bandwidth and transmission loss characteristics can be dynamically altered, providing improved performance for transceiver front-end tuning applications. The rate of roll-off of the frequency response can be adjusted to improve performance when used in duplexer applications. The tunable filter topology is applicable for both transmit and receive circuits. A method is described where the filter characteristics are adjusted to account for and compensate for the frequency response of the antenna used in a communication system.

An apparatus includes a radio-frequency (RF) receiver for receiving RF signals. The RF receiver includes a plurality of modulation signal detectors (MSDs) to generate a plurality of detection signals when a plurality of RF signals modulated using a plurality of modulation schemes are detected. The RF receiver further includes a controller to cause reception of the plurality of RF signals in response to the plurality of detection signals.