Granted Patent B2

US 7,764,942 · App. 11/825,414 · Granted Jul 27, 2010

Abstract

Claims (26)

1. A frequency-dependent impedance generator suitable for use in a radio frequency (RF) tuner, the frequency-dependent impedance generator comprising:

a) a first I/Q mixer, the first I/Q mixer mixing input RF signals with a first local oscillator signal;

b) a plurality of fixed-frequency filters, the plurality of fixed-frequency filters filtering the I/Q paths generated by the first I/Q mixer;

c) a second I/Q mixer, the second I/Q mixer mixing the filtered I/Q paths with the first local oscillator signal;

d) a summation module, the summation module summing the I/Q paths generated by the second I/Q mixer to generate a baseband signal; and

e) a transconductance amplifier, the transconductance amplifier shunt feeding back the baseband signal to the first I/Q mixer to generate the frequency-dependent impedance.

2. The frequency-dependent impedance generator according to claim 1 , wherein the frequency-dependent impedance generator functions as a notch filter.

3. The frequency-dependent impedance generator according to claim 1 , wherein the frequency-dependent impedance generator tracks the first local oscillator signal frequency.

4. The frequency-dependent impedance generator according to claim 1 , wherein the first I/Q mixer, the plurality of fixed-frequency filters, the second I/Q mixer, the summation module and the transconductance amplifier are implemented with analog technology.

5. The frequency-dependent impedance generator according to claim 1 , wherein the first I/Q mixer, the plurality of fixed-frequency filters, the second I/Q mixer, the summation module and the transconductance amplifier are implemented with Bi-CMOS technology.

6. A tracking amplifier suitable for use in an RF tuner, the tracking amplifier comprising:

a) a first I/Q mixer, the first I/Q mixer mixing input RF signals with a first local oscillator signal;

b) a plurality of fixed-frequency filters, the plurality of fixed-frequency filters filtering the I/Q paths generated by the first I/Q mixer;

c) a second I/Q mixer, the second I/Q mixer mixing the filtered I/Q paths with the first local oscillator signal;

d) a summation module, the summation module summing the I/Q paths generated by the second I/Q mixer to generate a baseband signal;

e) a transconductance amplifier, the transconductance amplifier shunt feeding back the baseband signal to the first I/Q mixer to generate the frequency-dependent impedance, said elements a through e forming a frequency-dependent impedance generator; and

f) an amplifier circuit; the frequency-dependent impedance generator being connected to the amplifier circuit, wherein the frequency-dependent impedance generator and the amplifier circuit generate a frequency-dependent transconductance, the frequency-dependent transconductance generating a frequency-dependent amplifier gain.

7. The tracking amplifier according to claim 6 , wherein the frequency-dependent amplifier gain tracks the first local oscillator signal frequency.

8. The tracking amplifier according to claim 6 wherein the tracking amplifier filters the input RF signals to in-band signal.

9. The tracking amplifier according to claim 6 , wherein the frequency-dependent impedance generator and the amplifier circuit are implemented with Bi-CMOS technology.

10. A method for generating a frequency-dependent impedance, the method comprising:

a) mixing input RF signals with a first local oscillator signal using a first I/Q mixer;

b) filtering the I/Q paths generated by the first I/Q mixer using a plurality of fixed-frequency filters;

c) mixing the filtered I/Q paths with the first local oscillator signal using a second I/Q mixer;

d) summing the I/Q paths generated by the second I/Q mixer to generate a baseband signal; and

e) shunt feeding back the baseband signal to the input of the RF tuner; thereby generating the frequency-dependent impedance.

Assignments (9)