Patent ID: 8467749

Claim:
An FM-band transmit power amplifier having an input and an output, comprising: a pre-filter including: a charge-pump based integrator coupled to said input and including a first current source, a first switch, a second switch, and a second current source coupled in series between a first node and a second node, a capacitor coupled to an integrator output node between said first and second switches and said second node, a first passive RC notch filter coupled to said integrator output node, a second passive RC notch filter coupled to said first passive RC notch filter, said first and second passive RC notch filters having a notch frequency in a band other than an FM band and having tunable capacitors such that said notch frequency is tunable, said band other than said FM band being selectable; and, an operational amplifier having a first input coupled to said integrator output node and a second input coupled to a reference voltage and an output coupled to said second current source to provide a negative feedback signal to adjust said second current source as a common-mode output voltage of said integrator varies; and an output driver coupled between said second passive RC notch filter and said output and having separately biased PMOS and NMOS transconductors configured to receive an output from said second passive RC notch filter.