Wide bandwidth bandpass filter comprising parallel connected piezoelectric resonators

A bandpass filter comprising:

• an input terminal;
• an output terminal;
• a common terminal;
• a first stacked piezoelectric resonator having a first input coupled to the input terminal, a first output coupled to the output terminal, and a first common electrode coupled to the common terminal;
• and
• a second stacked piezoelectric resonator having a second input coupled to the input terminal, a second common electrode coupled to the common terminal, and a second output coupled to the output terminal, wherein the bandpass filter has a passband.

A bandpass filter comprising:

• an input terminal;
• an output terminal;
• a common terminal;
• a first piezoelectric resonator having a first input coupled to the input terminal, a first output coupled to the output terminal, and a first common electrode coupled to the common terminal wherein the first piezoelectic resonator has a fundamental frequency that is within a passband of the bandpass filter;
• and
• a second piezoelectric resonator having a second input coupled to the input terminal, a second common electrode coupled to the common terminal, and a second output coupled to the output terminal wherein the second piezoelectric resonator has an odd overtone frequency that is within a percentage value of the fundamental frequency.

A bandpass filter comprising:

• an input terminal;
• an output terminal;
• a common terminal;
• a first piezoelectric resonator having a first input coupled to the input terminal, a first output coupled to the output terminal, and a first common electrode coupled to the common terminal;
• a second piezoelectric resonator having a second input coupled to the input terminal and and a second output;
• and
• a phase shift network having a first terminal coupled to the second output of the second piezoelectric resonator and a second terminal coupled to the output terminal wherein the phase shift network provides a phase shift of approximately one hundred eighty degrees (180.degree.) and wherein the first piezoelectric resonator has a first fundamental frequency that is within a passband of the bandpass filter and the second piezoelectric resonator has a second fundamental frequency that is within a percentage value of the first fundamental frequency.

A bandpass filter comprising:

• an input terminal;
• an output terminal;
• a common terminal;
• a first piezoelectric resonator having a first input coupled to the input terminal, a first output coupled to the output terminal, and a first common electrode coupled to the common terminal;
• a second piezoelectric resonator having a second input coupled to the input terminal, a second common electrode coupled to the common terminal, and a second output;
• and
• a third piezoelectric resonator having a third input coupled to the second output of the second piezoelectric resonator, a third output coupled to the output terminal, and a third common electrode coupled to the common terminal.