US 9,520,833 B1 · Active ring mixer

Abstract

An active ring mixer circuit for use in a receive or transmit channel of an RF radio. The circuit comprises plural transistor pairs arranged in a ring and biased into an active or saturation region. A first input is adapted to receive an RF signal. The first input is electrically combined with the plural transistor pairs to provide negative feedback to the plural transistor pairs. A second input electrically combined with the plural transistor pairs is adapted to receive a local oscillator signal. An output of the mixer is adapted to provide a mixed signal from the plural transistor pairs. Advantageously, the mixer circuit induces little low frequency spurs that may interfere with radio operation and has significantly reduced power consumption, lower noise figure, and good balance.

Claims14

Dependent claims

A method of mixing an RF signal comprising:

receiving a first signal at a first port of an active ring mixing circuit;
receiving a second signal at a second port of the active ring mixing circuit;
biasing transistors arranged in a ring as plural transistor pairs into an active region where the transistors operate with amplification with a DC voltage applied to the second signal, wherein the transistors are FET and the active region is a saturation region;
modifying a transconductance of the plural transistor pairs near a quiescent operating point to substantially maintain the plural transistor pairs in the active region;
combining the first and second signals to produce a mixed signal;
outputting the mixed signal at an output port of the active ring mixing circuit;
and
providing negative feedback through a source of the FET, wherein the first port is electrically connected to the source of the FET adapted to received a radio frequency signal.

5 more elements

An RF mixer comprising:

first and second transistor pairs arranged in a ring and biased into an active region of operation where the first and second transistor pairs operate with amplification with a DC voltage applied to a local oscillator signal;
a first input of the ring adapted to receive an RF signal through respective resistors of said first and second transistor pairs;
a second input of the ring coupled to respective gates of said first and second transistor pairs and adapted to receive a local oscillator signal, which modifies a transconductance of the first and the second transistor pairs near a quiescent operating point to substantially maintain the first and the second transistor pairs in the active region;
and
an intermediate frequency output of the ring adapted to provide a mixed signal from the transistor pairs whereby, during operation, said resistors of said first input produce negative feedback to enhance linearity of the RF mixer, wherein the transistors are FET having a source, gate, and drain, wherein the RF signal is applied to the source, the local oscillator signal is applied the gate, and the active region is a saturation region, and wherein the RF signal is applied to a source of the FET such that a negative feedback current through the source stabilizes the RF mixer.

2 more elements

An RF radio comprising:

at least one of a transmit and receive channel to process an RF signal;
an active ring mixer in the at least one of the transmit and receive channels that includes plural transistor pairs arranged in a ring;
a biasing circuit to bias the transistors into an active region where the transistors operate with amplification with a DC voltage applied to a local oscillator signal, wherein the transistors in the active ring mixer are FET and the active region is a saturation region;
a first input of the ring mixer to receive an RF input signal;
a second input of the ring mixer to receive the local oscillator signal which modifies a transconductance of the plural transistor pairs near a quiescent operating point to substantially maintain the plural transistor pairs in the active region;
a junction that combines the RF and local oscillator signals to produce an mixed signal;
and
an output to supply the mixed signal to the at least one of the transmit and receive channels, wherein the RF signal is applied to a source of the FET such that a negative feedback current through the source stabilizes the active ring mixer.

5 more elements

Dependencies are inferred from the claim text.

Active ring mixer

Life of this patent

Active ring mixer

Life of this patent

Abstract

Claims14