Bandpass filter with tunable resonator
First Claim
1. A tunable bandpass filter comprising:
- a first ferroelectric (FE) tank circuit comprising;
a first node to accept an input signal;
a first resonator having a first resonator input connected to the first node and a first resonator output connected to a reference voltage; and
a second capacitor having a second capacitor input connected to the first node, a second capacitor output connected to the reference voltage, and a control signal input to accept a control signal, the second capacitor comprising an FE material with a dielectric constant responsive to the control signal;
a second FE tank circuit comprising;
a second node to supply a bandpass filtered signal;
a second resonator having a second resonator input connected to the second node and a second resonator output connected to the reference voltage; and
a third capacitor having a third capacitor input connected to the second node, a third capacitor output connected to the reference voltage, and a second control signal input to accept a second control signal, the third capacitor comprising a second FE material with a second dielectric constant responsive to the second control signal; and
a first capacitor connected in series between the first node and the second node.
2 Assignments
0 Petitions
Accused Products
Abstract
A tunable bandpass filter is provided that comprises a first shunt-connected ferroelectric (FE) tunable tank circuit having a first node to accept an input signal. A second shunt-connected FE tunable tank circuit has a second node to supply a bandpass filtered signal. A first capacitor is connected in series between the first and second nodes. In one aspect, the first tank circuit comprises a first resonator connected to the first node, and a fourth capacitor connected between the first resonator and a reference voltage. The fourth capacitor is a tunable FE capacitor. Typically, a fifth capacitor is connected between the first node and the reference voltage. Likewise, the second tank circuit comprises a second resonator connected to the second node, and a sixth (FE) capacitor connected between the second resonator and the reference voltage. A seventh capacitor is connected between the second node and the reference voltage.
-
Citations
18 Claims
-
1. A tunable bandpass filter comprising:
-
a first ferroelectric (FE) tank circuit comprising; a first node to accept an input signal; a first resonator having a first resonator input connected to the first node and a first resonator output connected to a reference voltage; and a second capacitor having a second capacitor input connected to the first node, a second capacitor output connected to the reference voltage, and a control signal input to accept a control signal, the second capacitor comprising an FE material with a dielectric constant responsive to the control signal; a second FE tank circuit comprising; a second node to supply a bandpass filtered signal; a second resonator having a second resonator input connected to the second node and a second resonator output connected to the reference voltage; and a third capacitor having a third capacitor input connected to the second node, a third capacitor output connected to the reference voltage, and a second control signal input to accept a second control signal, the third capacitor comprising a second FE material with a second dielectric constant responsive to the second control signal; and a first capacitor connected in series between the first node and the second node.
-
-
2. A tunable bandpass filter comprising:
-
a first ferrorelectric (FE) tunable tank circuit comprising; a first node to accept an input signal; a first resonator having a first resonator input connected to the first node and a first resonator output; a first capacitor having a first capacitor input connected to the first resonator output, a first capacitor output connected to a reference voltage, and a first control input to accept a first control signal, the first resonator capacitor comprising a first FE material with a first dielectric constant responsive to the first control signal; and a second capacitor having a second capacitor input connected to the first node and a second capacitor output connected to the reference voltage; a second ferroelectric (FE) tunable tank circuit comprising; a second node to supply a band pass filtered signal; a second resonator having a second resonator input connected to the second node and a second resonator output; a third capacitor having a third capacitor input connected to the second resonator output, a third capacitor output connected to the reference voltage, and a third control input to accept a third control signal, the third capacitor comprising a third FE material with a third dielectric constant responsive to the third control signal; and a fourth capacitor having a fourth capacitor input connected to the second node and a fourth capacitor output connected to the reference voltage; and a fifth capacitor connected in series between the first node and the second node. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
-
-
15. A method for bandpass filtering a signal, the method comprising:
-
accepting an input signal on a first node, the first node electrically connected to a first tank circuit and a second tank circuit, the first tank circuit comprising a first resonator connected in series to a first ferroelectric (FE) capacitor and in parallel to a third capacitor, the second tank circuit comprising a second resonator connected in series to a second FE capacitor and in parallel to a fourth capacitor; tuning the first resonator of the first tank circuit comprising;
supplying a first control signal to the first FE capacitor to change a first dielectric constant of a first FE material of the first FE capacitor;tuning a second resonator of the second tank circuit comprising;
supplying a second control signal to the second FE capacitor to change a second dielectric constant of a second FE material of the second FE capacitor;in response to tuning the first resonator and the second resonator, bandpass filtering the input signal. - View Dependent Claims (16, 17)
-
-
18. A wireless telephone device with a tunable duplexer, the device comprising:
-
a receiver having an input; a transmitter having an output; an antenna having an antenna port; a duplexer comprising a first port connected to the antenna port, a second port connected to the transmitter output, and a third port; a tunable bandpass filter coupled between the duplexer third port and the receiver input, the tunable bandpass filter comprising; a first shunt-connected ferroelectric (FE) tunable tank circuit having a first node to accept an input signal, comprising; a first resonator connected between the first node an a reference voltage; and a second FE capacitor connected in parallel to the first resonator, the second FE capacitor comprising an FE material with a dielectric constant responsive to a control signal applied to the FE material; a second shunt-connected FE tunable tank circuit having a second node to supply a bandpass filtered signal, comprising; a second resonator connected between the second node an the reference voltage; and a third FE capacitor connected in parallel to the second resonator, the third FE capacitor comprising a third FE material with a third dielectric constant responsive to a third control signal applied to the third FE material; and a first capacitor connected in series between the first and second nodes.
-
Specification