Frequency translated filter
AssigneeBroadcom Corporation
InventorsAhmad Mirzaei, Hooman Darabi, John Leete
Life of this patent
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Abstract
Embodiments of a frequency translated filter (FTF) are presented. An FTF includes a passive mixer and a baseband impedance. The baseband impedance includes a network of one or more passive components (e.g., resistors, inductors, and capacitors) that form a low-Q filter. The passive mixer is configured to translate the baseband impedance to a higher frequency. The translated baseband impedance forms a high-Q filter and is presented at the input of the FTF. The FTF can be fully integrated in CMOS IC technology (or others, e.g., Bipolar, BiCMOS, and SiGe) and applied in wireless receiver systems including GSM, Wideband Code Division Multiple Access (WCDMA), Bluetooth, and wireless LANs (e.g., IEEE 802.11).
Claims29
A radio frequency (RF) receiver configured to receive and process an RF signal, the RF signal including a desired channel positioned within a particular frequency band, the RF receiver comprising:
- a low noise amplifier (LNA) coupled to the RF signal and configured to provide an amplified RF signal;
- and
- a frequency translated filter coupled between an input stage and a cascode stage of the LNA and configured to attenuate interferers in the RF signal outside the particular frequency band, the frequency translated filter comprising:
- a passive mixer configured to mix the RF signal received at a first mixer input and a local oscillator (LO) signal received at a second mixer input;
- and
- a baseband impedance coupled between an output of the passive mixer and ground,
- wherein the first mixer input presents a high-impedance path to ground for frequency components of the RF signal within the particular frequency band and a low-impedance path to ground for frequency components of the RF signal outside the particular frequency band.
A radio frequency (RF) receiver configured to receive and process an RF signal, the RF signal including a desired channel positioned within a particular frequency band, the RF receiver comprising:
- a passive mixer configured to mix the RF signal received at a first mixer input and a local oscillator (LO) signal received at a second mixer input;
- and
- a baseband impedance coupled between an output of the passive mixer and ground,
- wherein the first mixer input is coupled between an input stage and a cascode stage of an LNA and presents a high-impedance path to ground for frequency components of the RF signal within the particular frequency band and a low-impedance path to ground for frequency components of the RF signal outside the particular frequency band.
A frequency translated filter, comprising:
- a passive mixer configured to mix a radio frequency (RF) signal received at a first mixer input and a local oscillator (LO) signal received at a second mixer input;
- and
- a baseband impedance coupled between an output of the passive mixer and ground,
- wherein the first mixer input presents a high-impedance path to ground for frequency components of the RF signal within a desired frequency band and a low-impedance path to ground for frequency components of the RF signal outside the desired frequency band,
- wherein an impedance seen by the RF signal at the first mixer input is substantially equal to the baseband impedance translated in frequency by a frequency of the LO signal and is substantially given by:
- Z
- IN
-
- (
- jω
- RF
- )
- =
- R
- SW
- +
- 2
- π
- 2
-
- {
- Z
- BB
-
- (
- jω
- RF
- -
- jω
- LO
- )
- +
- Z
- BB
-
- (
- jω
- RF
- +
- jω
- LO
- )
- }
- wherein:
- ZIN is the translated baseband impedance;
- ZBB is the baseband impedance;
- ωRF is the frequency of the RF signal;
- ωLO is the frequency of the LO signal;
- and
- RSW is the switch resistance of a switching device used in the passive mixer.
Dependencies are inferred from the claim text.