Mixer and frequency converting apparatus

1. A mixer comprising:

an adder that inputs a first high-frequency signal and a second high-frequency signal for local use, adds the first high-frequency signal and the second high-frequency signal, and outputs as an addition signal;

a magnetoresistive effect element that includes a fixed magnetic layer, a free magnetic layer, and a non-magnetic spacer layer disposed between the fixed magnetic layer and the free magnetic layer, and is operable when the addition signal has been inputted, to multiply the first high-frequency signal and the second high-frequency signal included in the addition signal using a magnetoresistive effect to generate a multiplication signal;

a magnetic field applying unit that applies a magnetic field to the free magnetic layer; and

a first impedance converting unit that is passive, inputs the multiplication signal outputted from the magnetoresistive effect element, converts the multiplication signal to a lower impedance than an input impedance, and outputs the converted multiplication signal.

2. The mixer according to claim 1 ,

wherein the first impedance converting unit includes one of a transformer-type impedance converting circuit and a resistance-type impedance converting circuit.

3. A frequency converting apparatus comprising:

the mixer according to claim 2 ; and

a filter passing one frequency out of (f 1 +f 2 ) and (f 1 −f 2 ) out of the multiplication signal, where f 1 is the frequency of a higher frequency signal out of the first high-frequency signal and the second high-frequency signal and f 2 is the frequency of a lower frequency signal.

4. The frequency converting apparatus according to claim 3 ,

further comprising a signal generating unit that generates the second high-frequency signal,

wherein the signal generating unit includes:

a second magnetoresistive effect element including a fixed magnetic layer, a free magnetic layer, and a non-magnetic spacer layer disposed between the fixed magnetic layer and the free magnetic layer;

a second magnetic field applying unit that applies a magnetic field to the free magnetic layer of the second magnetoresistive effect element; and

a current supplying unit that supplies a DC current to the second magnetoresistive effect element,

wherein the second high-frequency signal is generated by spin injection self-oscillation by the second magnetoresistive effect element.

5. A frequency converting apparatus comprising:

the mixer according to claim 1 ; and

a filter passing one frequency out of (f 1 +f 2 ) and (f 1 −f 2 ) out of the multiplication signal, where f 1 is the frequency of a higher frequency signal out of the first high-frequency signal and the second high-frequency signal and f 2 is the frequency of a lower frequency signal.

6. The frequency converting apparatus according to claim 5 ,

further comprising a signal generating unit that generates the second high-frequency signal,

wherein the signal generating unit includes:

a second magnetoresistive effect element including a fixed magnetic layer, a free magnetic layer, and a non-magnetic spacer layer disposed between the fixed magnetic layer and the free magnetic layer;

a second magnetic field applying unit that applies a magnetic field to the free magnetic layer of the second magnetoresistive effect element; and

a current supplying unit that supplies a DC current to the second magnetoresistive effect element,

wherein the second high-frequency signal is generated by spin injection self-oscillation by the second magnetoresistive effect element.