A unit cell for a resistive mixer includes a plurality of active devices arranged in series, wherein each of said plurality of active devices having a different output conductance. A resistive mixer includes a plurality of active devices connected in series with one another to form a unit cell.

A signal up-conversion system is described. The system comprises a signal input for receiving an input signal to be up-converted; an oscillator system for generating an up-conversion signal having a selectable frequency; a mixer coupled to the input and to the oscillator, for combining the input signal and the up-conversion signal and to generate an up-converted signal; at least two filters, each of the at least two filters having different filtering characteristics; a signal output; a switch system configured to couple one of the at least two filters into a signal path between the output of the mixer and the signal output; and a controller configured to control a frequency of the up-conversion signal and a filter of the at least two filters coupled into the signal path by the switch system. A method switching between up-conversion frequencies is also described.

A radio frequency receiver comprising mixer circuitry to down-convert a received signal, which is transported on a signal line to baseband signal components, is provided. The mixer circuitry comprises a plurality of switched capacitors, each connected to the signal line through a signal side node and to a corresponding switch through a switch side node. In this context, a voltage is sensed at each switch side node of the plurality of switched capacitors and is read out through a respective grounded capacitor.

A double-balanced mixer, including a coupling transformer, a first diode cascade circuit, a second diode cascade circuit, and a first set of coils, is provided. The coupling transformer receives a first input signal and generates at least one set of signals with opposite voltage phases. The first diode cascade circuit is coupled to the coupling transformer, and generates a first node voltage according to a first set of bias voltages. The second diode cascade circuit is coupled to the coupling transformer, and generates a second node voltage according to a second set of bias voltages. The first set of coils is coupled to the first and second diode cascade circuits, receives the first and second node voltages and a second input signal, and generates an output signal. The first node voltage is equal to the second node voltage.

A double-balanced mixer, including a coupling transformer, a first diode cascade circuit, a second diode cascade circuit, and a first set of coils, is provided. The coupling transformer receives a first input signal and generates at least one set of signals with opposite voltage phases. The first diode cascade circuit is coupled to the coupling transformer, and generates a first node voltage according to a first set of bias voltages. The second diode cascade circuit is coupled to the coupling transformer, and generates a second node voltage according to a second set of bias voltages. The first set of coils is coupled to the first and second diode cascade circuits, receives the first and second node voltages and a second input signal, and generates an output signal. The first node voltage is equal to the second node voltage.

A mixer circuit including a mixer, a voltage divider circuit, and an amplifier, is provided. The mixer receives a first input signal, a second input signal, and at least one set of bias voltages, and generates an output signal. A frequency of the output signal is related to a frequency of the first input signal and a frequency of the second input signal. The voltage divider circuit receives the bias voltages and generates a common mode signal at an output end. The amplifier is coupled to the mixer to receive the output signal, and is coupled to the output end of the voltage divider circuit and configured to suppress noise in the output signal, and generate a final output signal.

A frequency multiplier includes an input section to receive a quadrature phase input signal having an input frequency, a mixer section coupled to the input section by a common mode node that forms a path for the common mode signal current to flow to the mixer section and magnetically coupled to the common mode node or capacitively coupled to the input section to generate a differential switching voltage at odd multiples of twice the input frequency, which switching voltage is applied to inputs of the mixer section, and an output section magnetically coupled to the mixer section, the output section being configured to generate an output voltage having a dominate frequency and sub-dominate frequencies spaced apart by the first multiple, the dominate frequency of the output voltage being a second multiple of the input frequency, where the second multiple is greater than the first multiple. Various arrangements are provided.

Methods and systems for receiving a differential input voltage signal at an input of a variable gain amplifier, and responsively generating an amplified differential output voltage signal on a pair of output nodes by driving a pair of load impedances connected to the pair of output nodes with an amplifier current according to the differential input voltage signal, enabling a cross-coupled differential pair connected in parallel to the pair of load impedances, the cross-coupled differential pair having drain inputs and cross-coupled gate inputs connected to the pair of output nodes to supplement a gain of the amplified differential voltage output voltage signal, and reducing a common mode voltage of the amplified differential output voltage signal by lowering the amplifier current driving the pair of load impedances via a bias control signal, the amplifier current lowered responsive to detecting the supplemented gain of the amplified differential output voltage signal.

A mixer includes a load portion connected between an input terminal of a first power voltage and an output terminal of the radio frequency transmit signal and configured to adjust a magnitude of the radio frequency transmit signal, a first switching unit connected to an output terminal of the radio frequency transmit signal, and configured to perform a first switching operation in response to a plurality of local oscillation signals, and a second switching unit connected between the first switching unit and an input terminal of a second power voltage, lower than the first power voltage, and configured to perform a second switching operation in response to a plurality of baseband signals, the plurality of local oscillation signals include an I+ baseband signal, an I− baseband signal, a Q+ baseband signal, and a Q− baseband signal, and the second switching unit includes a first branch performing a switching operation under control of the I+ baseband signal and the Q+ baseband signal, a second branch performing a switching operation under control of the I− baseband signal and the Q− baseband signal, a third branch performing a switching operation under control of the Q+ baseband signal and the I− baseband signal, and a fourth branch performing a switching operation under control of the Q− baseband signal and the I+ baseband signal.

A method and apparatus for input matching of a passive mixer are disclosed. The passive mixer includes a differential transistor pair including a first transistor and a second transistor, a first inductor having one end connected to the first transistor and another end connected to a ground, a second inductor having one end connected to the second transistor and another end connected to a ground, and a third inductor having one end for receiving a radio frequency (RF) signal and another end connected to a ground.