Low noise amplifiers (LNAs) with low noise figure are provided. In certain embodiments, an LNA includes a single-ended LNA stage including an input for receiving a single-ended input signal from an antenna and an output for providing a single-ended amplified signal, a balun for converting the single-ended amplified signal to a differential signal, and a variable gain differential amplification stage for amplifying the differential signal from the balun. Implementing the LNA in this manner provides low noise figure, high gain, flexibility in controlling gain, and less sensitivity to ground/supply impedance.

A method for removing offset in a receiver of an integrated circuit (IC) includes: determining digital codes of differential input voltages of an amplifier in a first receiving lane of the receiver; comparing the digital codes to a digital code corresponding to an optimum common mode voltage (VCM) of the receiver; according to the comparison, determining a bias code for adjusting both the differential input voltages to match the optimum VCM; and inputting the bias code to a bias circuit of the receiver. The first receiving lane of the receiver includes a plurality of amplifiers. The method steps are repeated for each amplifier of the plurality of amplifiers, and then repeated for all receiving lanes of the IC.

According to one embodiment, a transformer-based in-phase and quadrature (IQ) includes a differential balun having a first inductor and a second inductor. The first inductor has a first input terminal and a first output terminal. The second inductor has a second input terminal and a second output terminal. Additionally, the IQ generator circuit includes a third inductor magnetically coupled with the first inductor. The third inductor has a first isolation terminal and a third output terminal. The IQ generator circuit also includes a fourth inductor magnetically coupled with the second inductor. The fourth inductor has a second isolation terminal and a fourth output terminal. The IQ generator circuit additionally includes a first transistor coupled to the first input terminal of the first inductor. Further, the generator circuit includes a second transistor coupled to the second input terminal of the second inductor. The first transistor, the second transistor, the first inductor, and the second inductor form a part of a differential amplifier.

A chopper amplifier and method of operation are described. The chopper amplifier comprises a first chopper arranged to modulate an input signal using a first chopper signal having a chopper frequency. An amplification stage has an input arranged to receive the chopped signal and an output, and supplies an amplified signal at the output. An output chopper is arranged to integrate the amplified signal using a second chopper signal having the chopper frequency to generate an amplified output signal. The amplification stage is further configured to filter the chopped signal to attenuate signal components having frequencies lower than the chopper frequency.

An adaptive power amplifier and a radio frequency transmitter thereof are described. The radio frequency transmitter is a transmitter to transmit a transmission signal for a wireless communication system. The radio frequency transmitter includes at least one direct-current (DC) to direct-current (DC) converter coupled to an external power supply device for operation, a digital-to-analog converter configured to convert a digital signal into an analog signal, a filter configured to filter a harmonic component of the analog signal to generate an input signal, a RF up-converter configured to up-convert the input signal according to a desired channel frequency for generating a modulated signal, and a power amplifying circuit coupled to the DC-to-DC converter and the external power supply device, for selectively receiving one of different supply voltages for operation, and amplifying the modulated signal to generate a RF output signal.

Provided is a Radio Frequency (RF) communication apparatus and a method for detecting power. The RF communication apparatus includes a receiver that receives a segment value indicating one of multiple transmission output power ranges, a power detector that detects a strength of an RF transmission signal in an output power range corresponding to the segment value, and a transmitter that transmits the strength of the detected RF transmission signal. The power detector includes a feedback unit that receives the fed-back RF transmission signal, an RF core unit that generates a Root Mean Square (RMS) of the RF transmission signal, and a converter that converts a current signal corresponding to the RMS of the RF transmission signal into a voltage signal, and converts the converted voltage signal from a differential signal to a single signal.

A transformer includes multiple differential ports and first and second transformer windings. The first transformer winding includes a first transformer half-winding coupled to a first differential port of the differential ports. The first transformer winding also includes a second transformer half-winding coupled to a second differential port of the differential ports. An amplifier system that has a transformer is also provided. The amplifier system includes a first and a second stage amplifier. The first stage amplifier includes a first and a second amplifier. The second stage amplifier includes a third and a fourth amplifier. The transformer is coupled between the first stage amplifier and the second stage amplifier, where the transformer has a primary loop and a secondary loop. The primary loop of the transformer may be configured to receive differential signals of the first amplifier. A method for fabricating a transformer is also provided.

For broadband data communication, a data signal voltage at a signal input node can be converted to an output signal current at a signal output node. A first transistor device can contribute to the output signal current, with its transconductance or other gain reduced to accommodate larger signal swings, at which a second transistor can turn on and increase an effective resistance value of at least a portion of a gain degeneration resistor associated with the first transistor device. The second transistor can also contribute to the output signal current to help maintain or enhance an overall gain between the signal input node and the signal output node. Multiple secondary stages, push-pull arrangements, buffer amplifier configurations (which may or may not contribute to current in the gain degeneration resistor), input and output transformers, negative feedback to help reduce component variability, and frequency modification circuits or components are also described.

Radio Frequency (RF) amplifier design with RFIC suffers gain variations from gain variations due to wafer process variations, temperature changes, and supply voltage changes. Three methods are proposed to achieve constant amplifier gain, either through on-chip wafer calibration, or self-calibration. Through automatic adjustment of amplifier bias current, the proposed methods maintain constant amplifier gain over process, temperature, supply voltage variations. Under the proposed Method 1, a constant transconductance Gm with enhanced gain accuracy is maintained via wafer calibration. Under the proposed Method 2, a constant transconductance Gm is maintained by time-domain averaging through different transistors. Under the proposed Method 3, a constant Gm*R or RF gain is maintained considering the impedance of a matching network of the RF amplifier.

According to one embodiment, a transformer-based in-phase and quadrature (IQ) includes a differential balun having a first inductor and a second inductor. The first inductor has a first input terminal and a first output terminal. The second inductor has a second input terminal and a second output terminal. Additionally, the IQ generator circuit includes a third inductor magnetically coupled with the first inductor. The third inductor has a first isolation terminal and a third output terminal. The IQ generator circuit also includes a fourth inductor magnetically coupled with the second inductor. The fourth inductor has a second isolation terminal and a fourth output terminal. The IQ generator circuit additionally includes a first transistor coupled to the first input terminal of the first inductor. Further, the generator circuit includes a second transistor coupled to the second input terminal of the second inductor. The first transistor, the second transistor, the first inductor, and the second inductor form a part of a differential amplifier.