A communications receiver with improved blocker performance including multiple gain tables selected based on a number of reductions or back offs from a maximum coarse gain setting. A receiver chain with multiple gain stages converts a received signal to a digital format, determines the power level of the received signal, and provides an overload indication. A first gain table maximizes SNR and SNDR for weak blockers and at least one additional gain table successively improves SNDR for stronger blockers. An AGC circuit initially sets the coarse gain setting to maximum, and backs off a number of coarse gain steps until the receiver chain is not overloaded. The number of back off steps is used to select a gain table, the power level is used to select an entry in the selected table, and the selected entry includes gain settings for the gain stages of the receiver chain.

The disclosure relates to technology for an adjustable gain device that includes differential input terminals, differential output terminals, signal processing circuitry, and first and second cross-coupled segments. The first cross-coupled segment is coupled between differential input terminals of the adjustable gain device and a negative input of the signal processing circuitry. The second cross-coupled segment is coupled between differential input terminals of the adjustable gain device and a positive input of the signal processing circuitry. The adjustable gain device has a gain that is adjustable by adjusting values of the first and second cross-coupled segments, while maintaining a substantially consistent frequency response and a substantially consistent input impedance of the adjustable gain device, so long as a specified relationship between values of the first and second cross-coupled segments is kept substantially constant.

The disclosure relates to technology for a receiver having a receive signal path including a mixer, a differential fixed gain or variable gain amplifier, and a differential filter. The mixer is configured to receive an RF signal, receive an oscillator signal, and output a differential down converted signal at one of a baseband or intermediate frequency (IF). The amplifier is downstream of the mixer and configured to receive the differential down converted signal from the mixer, apply a gain thereto, and output an amplified differential signal. The filter is downstream of the amplifier and configured filter the amplified differential signal received from the amplifier, and output a filtered differential signal. By locating the differential filter downstream of the differential amplifier within the receive signal path, distortion caused by the mixer is mitigated compared to if the filter were located upstream of the filter.

A radio frequency (RF) signal strength detection technique is disclosed with a received signal strength indicator (RSSI) circuit, which can be deployed in an internet-of-things (IoT) network. The RSSI circuit is based on a direct conversion of RF to digital code indicating the signal strength. The direct conversion is achieved by the repeated switching of a rectifier's output voltage using an ultra-low power comparator. A 5-bit programmable feedback circuit can be used to correct detection inaccuracies. The RSSI circuit can be implemented in a 65-nm CMOS process and consumes 15 nW power. It can have a linear dynamic range of 26 dB and exhibit an error of 0.5 dB with a wide bandwidth of 500 MHz. The technique has been verified with simulation and measurement results. The high detection accuracy with ultra-low power consumption of the proposed RSSI circuit is favorable for IoT applications including, e.g., biomedical, localization, and other low-power applications.

An integrated circuit device is provided. In some examples, the integrated circuit device includes an amplifier stage that receives an input signal and a control signal and provides an amplified signal in response. A main path is coupled to the amplifier stage that receives the amplified signal and provides a first feedback signal corresponding to a signal strength of a data-bearing portion of the input signal. A control path also receives the amplified signal and provides a second feedback signal corresponding to a signal strength of the data-bearing portion and an interference component. A gain control circuit is coupled to the main path and the control path that receives the first and second feedback signals and provides the control signal in response to the feedback signals. In some such examples, the control path and main path include separate mixer stages with different performance characteristics.

Variable gain amplifiers (VGA) with output phase invariance are provided herein. In certain embodiments, a VGA is operable in a selected gain setting chosen from multiple gain settings that provide different amounts of amplification to a radio frequency (RF) input signal. The VGA includes a gain transistor that has a substantially constant bias current across the gain settings, such that the VGA's output phase, input impedance matching, and/or input return loss are substantially constant. The gain setting of the VGA is selected by controlling relative biasing of a pair of cascode transistors each connected to the gain transistor by a corresponding degeneration resistor. The degeneration resistors provide compensation that reduces or eliminates a difference in output phase of the VGA across gain settings, for instance, by introducing a zero in a transfer function of the VGA that cancels a pole arising from the cascode transistors.

According to one embodiment, a low noise amplifier (LNA) circuit includes a first stage which includes: a first transistor; a second transistor coupled to the first transistor; a first inductor coupled in between an input port and a gate of the first transistor; and a second inductor coupled to a source of the first transistor, where the first inductor and the second inductor resonates with a gate capacitance of the first transistor for a dual-resonance. The LNA circuit includes a second stage including a third transistor; a fourth transistor coupled between the third transistor and an output port; and a passive network coupled to a gate of the third transistor. The LNA circuit includes a capacitor coupled in between the first and the second stages, where the capacitor transforms an impedance of the passive network to an optimal load for the first amplifier stage.

A front end module (FEM) and associated method for receiving signals in a front end module are disclosed. Some embodiments of the FEM have three inputs. The FEM can process the input signals in one of three bypass modes. In bypass modes, switchable tank circuits provide a high impedance to isolate active components from the bypass path. This improves the input return loss in the passive bypass mode and thus improves the performance of the passive bypass mode by allowing the use of LNAs without an input switch. In the active gain mode, one of a plurality of signals are amplified by one of an equal number of amplifiers coupled to the FEM output. Accordingly, the FEM can output signals applied to any one of the FEM inputs in bypass mode, or an amplified version of one of the input signals. In some embodiments, the FEM has only one input and one LNA. In such embodiments, an output selector switch selects between a bypass path and a gain path.

An RF frontend IC device includes an RF transceiver to transmit and receive RF signals and a frequency synthesizer to perform frequency synthetization to operate within a predetermined frequency band. The frequency synthesizer generates an LO signal to the RF transceiver to enable the RF transceiver to transmit and receive RF signals within the predetermined frequency band. The frequency synthesizer includes a QPG circuit to generate signals shifted in phases based on the LO signal and a phase shifting circuit to generate quadrant signals based on the signals shifted in phases. Each of the quadrant signals corresponds to one of the four quadrants in phases in the respective quadrant spaces. The phase shifting circuit includes multiple phase switches operable in a collaboration manner to further shift in phase based on the signal shifted in phases to generate the quadrant signals in proper quadrant spaces.

The disclosure provides an RF receiver. The RF receiver includes an input driver. The input driver receives a coarse signal, and generates an input signal. A digital step attenuator (DSA) is coupled to the input driver and receives the input signal. An analog to digital converter (ADC) is coupled to the DSA. The DSA includes a serial capacitor coupled to the input driver. The DSA also includes a sampling capacitor coupled to the ADC.