Mixer-first radio receiver circuitry
AssigneeRockwell Collins, Inc.
InventorDavid W. Cripe
Life of this patent
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Abstract
The mixer-first topology of receivers do not include low-noise amplifiers (LNA) preceding the mixer. The Mixer-First topology of radio receivers utilizes a direct-conversion quadrature mixer to down convert an RF signal to baseband, where a Hilbert Transform filter is used for sideband selection. When a switching mixer is used, the mixer-first receiver is capable of extremely high dynamic range and linearity. The downfall of the mixer-first topology is poor out-of-band signal rejection. A mixer-first receiver is described which achieves third-harmonic rejection without bandpass filtering proceeding the mixer.
Claims18
A receiver comprising:
- a local oscillator (LO) configured to generate an LO signal comprising an LO frequency;
- a single-pole, triple-throw (SP3T) switch comprising:
- a radio frequency (RF) port configured to receive an RF signal comprising a baseband signal modulated onto a carrier signal;
- an LO port configured to receive the LO signal;
- a 0-degree port, a 120-degree port, and a 240-degree port;
- wherein the SP3T switch is configured to sequentially switch the RF port to each of the 0-degree port, the 120-degree port, and the 240-degree port at the LO frequency;
- wherein the LO frequency is three times the carrier frequency such that the RF port is sequentially switched to each of the 0-degree port, the 120-degree port, and the 240-degree port once during each period of the LO frequency and such that the SP3T switch switches between the 0-degree port, the 120-degree port, and the 240-degree port for a third of each period of the RF signal;
- a first capacitor coupled between the 0-degree port and ground;
- a second capacitor coupled between the 120-degree port and ground;
- a third capacitor coupled between the 240-degree port and ground;
- and
- an image-reject filter coupled to the 0-degree port, the 120-degree port, and the 240-degree port;
- wherein the image-reject filter is configured to output the baseband signal.
A system comprising:
- an antenna configured to generate a radio frequency (RF) signal;
- a receiver coupled to the antenna, the receiver comprising:
- a local oscillator (LO) configured to generate an LO signal comprising an LO frequency;
- a single-pole, triple-throw (SP3T) switch comprising:
- a radio frequency (RF) port configured to receive the RF signal comprising a baseband signal modulated onto a carrier signal;
- an LO port configured to receive the LO signal;
- a 0-degree port, a 120-degree port, and a 240-degree port;
- wherein the SP3T switch is configured to sequentially switch the RF port to each of the 0-degree port, the 120-degree port, and the 240-degree port at the LO frequency;
- wherein the LO frequency is three times the carrier frequency such that the RF port is sequentially switched to each of the 0-degree port, the 120-degree port, and the 240-degree port once during each period of the LO frequency and such that the SP3T switch switches between the 0-degree port, the 120-degree port, and the 240-degree port for a third of each period of the RF signal;
- a first capacitor coupled between the 0-degree port and ground;
- a second capacitor coupled between the 120-degree port and ground;
- a third capacitor coupled between the 240-degree port and ground;
- and
- an image-reject filter coupled to the 0-degree port, the 120-degree port, and the 240-degree port;
- wherein the image-reject filter is configured to output the baseband signal.
Dependencies are inferred from the claim text.