Switchable gain amplifier having a high-pass filter pole

A radio receiver comprising:

• mixing circuitry adapted to downconvert a received radio frequency signal and provide a differential downconverted signal;
• and
• a switchable gain amplifier coupled to an output of the first mixing circuitry and adapted to amplify the downconverted signal, the switchable gain amplifier comprising:
• a first input node adapted to receive a first component of the downconverted signal;
• a second input node adapted to receive a second component of the downconverted IF signal;
• a first differential amplifier having a first input terminal and a second input terminal, the first input terminal coupled to the first input node;
• a second differential amplifier having a first input terminal and a second input terminal, the first input terminal coupled to the second input node;
• a first variable resistance having a first terminal coupled to the first input terminal of the first differential amplifier and a second terminal coupled to the second input terminal of the first differential amplifier;
• a second variable resistance having a first terminal coupled to the first input terminal of the second differential amplifier and a second terminal coupled to the second input terminal of the second differential amplifier;
• and
• a differential capacitor coupled between the second terminal of the first variable resistance and the second terminal of the second variable resistance.

A radio transmitter comprising:

• circuitry adapted to provide a differential transmit signal;
• a switchable gain amplifier coupled to an output of the circuitry and adapted to amplify the differential transmit signal and provide an amplified transmit signal, the switchable gain amplifier comprising:
• a first input node adapted to receive a first component of the differential transmit signal;
• a second input node adapted to receive a second component of the differential transmit signal;
• a first differential amplifier having a first input terminal and a second input terminal, the first input terminal coupled to the first input node;
• a second differential amplifier having a first input terminal and a second input terminal, the first input terminal coupled to the second input node;
• a first variable resistance having a first terminal coupled to the first input terminal of the first differential amplifier and a second terminal coupled to the second input terminal of the first differential amplifier;
• a second variable resistance having a first terminal coupled to the first input terminal of the second differential amplifier and a second terminal coupled to the second input terminal of the second differential amplifier;
• and
• a differential capacitor coupled between the second terminal of the first variable resistance and the second terminal of the second variable resistance;
• and
• mixing circuitry adapted to convert the amplified transmit signal to a radio frequency signal.