Gain reduction techniques for radio-frequency amplifiers

A radio-frequency amplifier comprising:

• a first input transistor having a first source-drain terminal coupled to a ground power supply line, a second source-drain terminal coupled to a first amplifier output terminal, and a gate terminal configured to receive a radio-frequency signal;
• a second input transistor having a first source-drain terminal coupled to the ground power supply line, a second source-drain terminal coupled to a second amplifier output terminal, and a gate terminal configured to receive the radio-frequency signal;
• a first cascode transistor having a first source-drain terminal coupled to the second source-drain terminal of the first input transistor, a second source-drain terminal coupled to the first amplifier output terminal, and a gate terminal configured to receive a bias voltage;
• a second cascode transistor having a first source-drain terminal coupled to the second source-drain terminal of the second input transistor, a second source-drain terminal coupled to the second amplifier output terminal, and a gate terminal configured to receive the bias voltage;
• and
• a gain adjustment transistor having a first source-drain terminal coupled to the first source-drain terminal of the first cascode transistor, a second source-drain terminal coupled to the first source-drain terminal of the second cascode transistor, and a gate terminal configured to receive a gain control voltage, wherein the first and second input transistors have a first channel type, and wherein the gain adjustment transistor has a second channel type different than the first channel type.

An electronic device comprising:

• one or more processors configured to output transmit signals;
• a transceiver configured to generate radio-frequency signals based on the transmit signals output from the one or more processors and configured to receive radio-frequency signals from an antenna;
• and
• a radio-frequency amplifier configured to amplify the radio-frequency signals generated by the transceiver or received at the transceiver, the radio-frequency amplifier having
• a first input transistor having a source terminal coupled to a ground power supply line, a drain terminal coupled to a first amplifier output terminal, and a gate terminal configured to receive the radio-frequency signals;
• a second input transistor having a source terminal coupled to the ground power supply line, a drain terminal coupled to a second amplifier output terminal, and a gate terminal configured to receive the radio-frequency signals;
• capacitance neutralization transistors that are cross-coupled with the first and second input transistors;
• one or more resistors coupled in series with the capacitance neutralization transistors;
• and
• one or more gain adjustment transistors coupled in parallel with the one or more resistors.