An apparatus is disclosed for mixing signals. In example aspects, the apparatus includes a mixer circuit having multiple local oscillator nodes, a first node corresponding to a first frequency, and multiple second nodes corresponding to a second frequency. The mixer circuit includes multiple capacitors coupled between the multiple local oscillator nodes and the multiple second nodes. The mixer circuit has multiple switches including a first switch, a second switch, a third switch, and a fourth switch. The multiple switches are coupled between the multiple capacitors and the multiple second nodes. The first switch and the second switch are coupled between the multiple capacitors and the first node. The first switch and the second switch are disposed between the fourth switch and the third switch.

A band-switching network includes a dual-band balun and a switch network. The dual-band balun includes a first output and a second output. The switch network includes a first switch and a second switch in which an input to the first switch is coupled to the first output and an input to the second switch is coupled to the second balanced output. The dual-band balun further includes a primary coil, a first secondary coil and a second secondary coil in which the first secondary coil is coupled to the first balanced output and the second secondary coil is coupled to the second balanced output. In one embodiment, the primary coil and the first secondary coil are coupled by a first coupling factor k.sub.1, and the primary coil and the second secondary coil are coupled by a second coupling factor k.sub.2 that is different from the first coupling factor k.sub.1.

To provide a mixer and a semiconductor device which each have a small circuit area and each of which operation capability is inhibited from being decreased due to heat. The mixer includes a differential portion, a current source, a first load, an input terminal, and a first output terminal; the differential portion includes a first and a second transistor; and each of the first and the second transistors includes a metal oxide in a channel formation region. A first terminal of each of the first and the second transistors is electrically connected to the input terminal and a current source and a second terminal of the first transistor is electrically connected to a first terminal of the first load and the first output terminal. The first load has a function of supplying a current between the first terminal and a second terminal of the first load by application of voltage to the second terminal of the first load, and the current source has a function of supplying a constant current to the current source from the first terminal of each of the first and the second transistors. The current source includes a transistor including silicon in a channel formation region, and the differential portion is positioned above the current source.

The present disclosure provides a mixing circuit with high harmonic suppression ratio, including: a multi-phase generation module, which receives a first input signal and generates eight first square wave signals with a phase difference of 45°; a quadrature phase generation module, which receives a second input signal and generates four second square wave signals with a phase difference of 90°; a harmonic suppression module, connected with an output end of the quadrature phase generation module to filter out higher order harmonic components in the second square wave signals; and a mixing module, connected with output ends of the multi-phase generation module and the harmonic suppression module to mix output signals of the multi-phase generation module and the harmonic suppression module. The mixing circuit with high harmonic suppression ratio adds a harmonic suppression module on the basis of multi-phase mixing, thereby improving the harmonic suppression ratio of the output signal.

A detector circuit includes: a squaring circuit configured to receive an output of a power amplifier of a radio transmitter and to produce an output current, the output of the power amplifier including: a desired tone; a local oscillator leakage tone; and an image tone, and the output current of the squaring circuit including: a direct current (DC) component including a function of the desired tone and an alternating current (AC) component; and a DC current absorber electrically connected to an output terminal of the squaring circuit, the DC current absorber being configured to filter out the DC component of the output current of the squaring circuit to produce a filtered output of the squaring circuit, the filtered output including the AC component including functions of the local oscillator leakage tone and the image tone.

Embodiments of power efficient radio mixers are provided. A generalized impedance matched low-voltage active mixer circuit technique, which utilizes a plurality of commutator cells and transformers, is disclosed. The low voltage active mixer function is coupled to an impedance matched amplifier allowing for insertion of image rejection filtering between the amplifier and the mixing function. The commutator cells can be driven in parallel by common local oscillator (LO) and intermediate frequency (IF) ports combined in parallel to yield highly linear mixers. A multi-channel receiver with a common impedance matched radio frequency (RF) amplifier driving a plurality of commutator cells with multiple LOs and IFs is also disclosed.

A detector circuit includes: a squaring circuit configured to receive an output of a power amplifier of a radio transmitter and to produce an output current, the output of the power amplifier including: a desired tone; a local oscillator leakage tone; and an image tone, and the output current of the squaring circuit including: a direct current (DC) component including a function of the desired tone and an alternating current (AC) component; and a DC current absorber electrically connected to an output terminal of the squaring circuit, the DC current absorber being configured to filter out the DC component of the output current of the squaring circuit to produce a filtered output of the squaring circuit, the filtered output including the AC component including functions of the local oscillator leakage tone and the image tone.

Embodiments of power efficient radio mixers are provided. A generalized impedance matched low-voltage active mixer circuit technique, which utilizes a plurality of commutator cells and transformers, is disclosed. The low voltage active mixer function is coupled to an impedance matched amplifier allowing for insertion of image rejection filtering between the amplifier and the mixing function. The commutator cells can be driven in parallel by common local oscillator (LO) and intermediate frequency (IF) ports combined in parallel to yield highly linear mixers. A multi-channel receiver with a common impedance matched radio frequency (RF) amplifier driving a plurality of commutator cells with multiple LOs and IFs is also disclosed.

Embodiments of power efficient radio frequency mixers are provided. A generalized impedance matched low-voltage active mixer circuit technique, which utilizes a plurality of commutator cells and transformers, is disclosed. The active mixer techniques are reconfigurable between various operation configurations based, at least in part, on selectively activating at least one of a plurality of commutator cells. The low voltage active mixer function is coupled to an impedance matched amplifier which can be bypassed allowing changes in the gain of the mixer circuit suites while preserving impedance matching.

An electronic device may include wireless circuitry having a radio-frequency mixer. The mixer may include an input stage, an output stage, and a transformer coupled between the input and output stages. The input stage may include input transistors forming a transconductance cell. The output stage may include two pairs of mixer transistors configured to receive an oscillating signal. The transformer may include a primary coil coupled between the input transistors and a secondary coil coupled between the two pairs of mixer transistors. A harmonic rejection circuit may be coupled to a center tap of the secondary coil. The harmonic rejection circuit may be configured to mitigate harmonic signals that are associated with the oscillating signal and that are generated at the inputs of the output stage. The harmonic rejection circuit may include an inductor, an optional capacitor, an optional current source transistor, or other passive component.