N-path bandstop filter with extended spurious-free upper passband

A radio frequency (RF) filter circuit comprising:

• a bandstop filter input and a bandstop filter output;
• a bandstop filter circuit connected between the bandstop filter input and the bandstop filter output, the bandstop filter circuit including a plurality of capacitors arranged in parallel and a plurality of switches, each of the switches arranged in series with a respective one of the capacitors;
• a bridged T-coil circuit arranged between the bandstop filter input and the bandstop filter output, the bridged T-coil circuit including at least two bridge inductors in parallel with at least one bridge capacitor;
• and
• a clock waveform generator configured to generate a plurality of clock pulses, each of the clock pulses having a ⅓ duty cycle, wherein each of the switches is configured to be controlled by one of the clock pulses.

A radio frequency (RF) filter circuit comprising:

• a bandstop filter input and a bandstop filter output;
• a clock waveform generator configured to generate a plurality of clock pulses, each of the clock pulses having a fractional duty cycle;
• and
• a bandstop filter circuit connected between the bandstop filter input and the bandstop filter output, the bandstop filter circuit including N capacitors arranged in parallel and a plurality of switches, each of the switches arranged in series with a respective one of the capacitors, each of the switches configured to be controlled by one of the clock pulses, wherein N is an odd integer and wherein at least two of the clock pulses overlap for a portion of the clock pulses widths.