Differential switchable capacitors for radiofrequency power amplifiers

A transceiver system comprising:

• a power amplifier to generate an output signal at an output terminal as a function of applying gain to an input signal;
• and
• a resonant circuit comprising an inductor and a switchable capacitor system, the switchable capacitor system comprising a plurality of differential switchable capacitors, each differential switchable capacitor comprising:
• a positive differential terminal coupled with the output terminal to receive a first differential input signal responsive to the output signal;
• a negative differential terminal;
• a capacitor control switch (CCS) having a positive CCS node and a negative CCS node, the CCS to selectively toggle between a first mode and a second mode in response to a CCS control signal;
• a first capacitor coupled between the positive CCS node and the positive differential terminal;
• a second capacitor coupled between the negative CCS node and the negative differential terminal;
• and
• a switch network to selectively toggle between the first mode and the second mode in response to a switch network control signal, such that:
• in the first mode, the CCS control signal is set to a high reference voltage to electrically couple the first capacitor with the second capacitor, and the switch network is to pull the positive CCS node and the negative CCS node to a low reference voltage level;
• and
• in the second mode, the CCS control signal is set to a low control voltage to electrically decouple the first capacitor from the second capacitor, and the switch network is to pull the positive CCS node and the negative CCS node to the high reference voltage level, the low control voltage level being greater than zero and set to a level in accordance with the high reference voltage minus a peak signal voltage.

A method for tuning a resonant circuit using differential switchable capacitors, the method comprising:

• applying a capacitor control switch (CCS) control signal to a switchable capacitor system having a plurality of differential switchable capacitors, the CCS control signal identifying a differential switchable capacitor of the plurality of differential switchable capacitors, such that applying the CCS control signal causes the identified differential switchable capacitor to turn ON, thereby coupling a positive differential terminal with a negative differential terminal via a capacitive channel of the identified differential switchable capacitor,
• the capacitive channel being one of a plurality of capacitive channels, each capacitive channel comprised by a respective one of the plurality of differential switchable capacitors, and each capacitive channel having an associated capacitance defined by a respective first capacitor and a respective second capacitor and having a respective CCS responsive to the CCS control signal, each respective first capacitor coupled between the respective CCS and the positive differential terminal, and each respective second capacitor coupled between the respective CCS and the negative differential terminal,
• applying the CCS control signal comprising applying a high reference voltage to the respective CCS of the capacitive channel comprised by the identified differential switchable capacitor to turn ON the identified differential switchable capacitor, and applying a low control voltage to the respective CCS of at least another capacitive channel comprised by at least another of the differential switchable capacitors to turn OFF the at least another of the differential switchable capacitors, the low control voltage being greater than zero and being set to a level in accordance with the high reference voltage minus a peak signal voltage of the first data signal;
• applying a first data signal to the positive differential terminal, the first data signal corresponding to an output signal from a power amplifier in electrical communication with the positive differential terminal;
• and
• applying a second data signal to the negative differential terminal.