Abstract: Apparatus and methods for compensating radio frequency (RF) transmitters for local oscillator (LO) leakage are provided herein. In certain configurations herein, a transmitter generates an RF transmit signal based on mixing an input signal with an LO signal. Additionally, the transmitter is calibrated to compensate for LO leakage, which provides a number of benefits, including lower levels of undesired emissions from the transmitter.

Abstract: The present disclosure provides a voltage variable attenuator (VVA) with a controllable matching network. The output of the attenuation portion of the VVA is couple to a matching network. The matching network includes a resistive element, which may be a Field Effect Transistor (FET), whose resistance may be controlled as a function of attenuation. In particular, a control voltage used to control the resistance of the attenuation portion of the VVA is also used to control the resistive element of the matching network. In this manner, the output impedance of the VVA may be maintained at a desired level.

Abstract: Modular gain control based on blocker signal detection is disclosed herein. In a multi-stage gain control scheme for a receiver, the input stage gain or the pre-mixing stage gain can be controlled for effective blocker rejection based on detecting a blocker signal at a mixer, and the output stage gain or the post-mixing stage gain can be controlled to restore and maintain an appropriate output level after pre-mixing gain reduction performed for blocker rejection. Accordingly, the RF communication systems herein can include multiple loops for providing AGC. In particular, an RF communication system can include a main loop and a blocker loop used to override the main loop when the blocker signal is detected. In certain configurations, the blocker loop reduces the gain of an RF VGA, while the main loop will increase the gain of an IF VGA to restore the output power.

Abstract: The present disclosure provides a voltage variable attenuator (VVA) with a controllable matching network. The output of the attenuation portion of the VVA is couple to a matching network. The matching network includes a resistive element, which may be a Field Effect Transistor (FET), whose resistance may be controlled as a function of attenuation. In particular, a control voltage used to control the resistance of the attenuation portion of the VVA is also used to control the resistive element of the matching network. In this manner, the output impedance of the VVA may be maintained at a desired level.

Abstract: Provided herein are apparatus and methods for high linearity voltage variable attenuators (VVAs). In certain configurations, a high linearity VVA includes multiple shunt arms or circuits that operate in parallel with one another between a signal node and a first DC voltage, such as ground. Thus, the shunt arms are in shunt with respect to a signal path of the VVA. The multiple shunt arms include a first shunt arm of one or more n-type field effect transistor (NFETs) and a second shunt arm of one or more p-type field effect transistor (PFETs). The gates of the NFETs are controlled using a control voltage, and the gates of the PFETs are controlled using a complementary control voltage that changes inversely with respect to the control voltage.

Abstract: Provided herein are apparatus and methods for high linearity voltage variable attenuators (VVAs). In certain configurations, a high linearity VVA includes multiple shunt arms or circuits that operate in parallel with one another between a signal node and a first DC voltage, such as ground. Thus, the shunt arms are in shunt with respect to a signal path of the VVA. The multiple shunt arms include a first shunt arm of one or more n-type field effect transistor (NFETs) and a second shunt arm of one or more p-type field effect transistor (PFETs). The gates of the NFETs are controlled using a control voltage, and the gates of the PFETs are controlled using a complementary control voltage that changes inversely with respect to the control voltage.

Abstract: Modular gain control based on blocker signal detection is disclosed herein. In a multi-stage gain control scheme for a receiver, the input stage gain or the pre-mixing stage gain can be controlled for effective blocker rejection based on detecting a blocker signal at a mixer, and the output stage gain or the post-mixing stage gain can be controlled to restore and maintain an appropriate output level after pre-mixing gain reduction performed for blocker rejection. Accordingly, the RF communication systems herein can include multiple loops for providing AGC. In particular, an RF communication system can include a main loop and a blocker loop used to override the main loop when the blocker signal is detected. In certain configurations, the blocker loop reduces the gain of an RF VGA, while the main loop will increase the gain of an IF VGA to restore the output power.

Abstract: Provided herein are high frequency signal attenuators. In certain configurations, an integrated circuit includes a signal conductor that carries a radio frequency (RF) signal, a shield conductor routed with the signal conductor and biased with a ground voltage, and an attenuation circuit that provides a controllable amount of attenuation to the RF signal. The attenuation circuit includes a shunt circuit electrically connected between a signal tapping position of the signal conductor and a shield tapping position of the shield conductor. Connecting the shunt circuit in this manner enhances high frequency performance by reducing a length of an effective loop from the signal conductor to an adjacent portion of the shield conductor.