Radio frequency (RF) mixer circuits having a complementary frequency multiplier module that requires no balun to multiply a lower frequency base oscillator signal to a higher frequency local oscillator (LO) signal, and which has a significantly reduced IC area compared to balun-based frequency multipliers. In one embodiment, the complementary frequency multiplier module includes a complementary pair of FETs controlled by an applied base oscillator signal. The complementary FETs are coupled to a common-gate FET amplifier and alternate becoming conductive in response to the base oscillator signal. The alternating switching of the complementary FETs in response to the opposing phases of the base oscillator signal cause the common-gate FET amplifier to output a higher frequency local oscillator (LO) signal. The LO signal is coupled to the LO input of a mixer or mixer core of a type suitable for use in conjunction with a frequency multiplier.

Mixers with improved linearity are disclosed. A diode or FET ring mixer is implemented with at least one parallel shunt element coupled with the ring mixer, the shunt element providing shunt to a diode or FET, for example, to reduce the effect of nonlinear or off resistance and/or capacitance. Linearity, isolation, symmetry, even order harmonics of the ring mixer, or any combination thereof can be improved as a result. The linearity of the ring mixer with parallel shunt resistors can be further improved by adding series resistors in the ring according to certain embodiments.

A FET based double balanced mixer (DBM) that exhibits good conversion gain and IIP3 values and provides improved linearity and wide bandwidth. In one embodiment, a first balun is configured to receive a local oscillator (LO) signal and generate two balanced LO signals that are coupled to two corresponding opposing nodes of a four-node FET ring. A second balun is configured to pass an RF signal on the unbalanced side. The FET ring includes at least four FETs connected as branches of a ring, with the source of each FET connected to the drain of a next FET in the ring. Each FET is preferably fabricated as, or configured as, a low threshold voltage device having its gate connected to its drain, which causes the FET to operate as a diode, but with the unique characteristic of having close to a zero turn-on voltage.

An apparatus includes a first circuit and a second circuit. The first circuit may have a first diode and a second diode connected as anti-parallel diodes and physically adjacent to each other in a substrate. The second circuit may have a third diode and a fourth diode connected as anti-parallel diodes and physically adjacent to each other in the substrate. The first circuit and the second circuit may be configured to mix two input signals to generate an output signal. A polarity of every other physically neighboring diode may be reversed.

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.

Radio frequency (RF) mixer circuits having a complementary frequency multiplier module that requires no balun to multiply a lower frequency base oscillator signal to a higher frequency local oscillator (LO) signal, and which has a significantly reduced IC area compared to balun-based frequency multipliers. In one embodiment, the complementary frequency multiplier module includes a complementary pair of FETs controlled by an applied base oscillator signal. The complementary FETs are coupled to a common-gate FET amplifier and alternate becoming conductive in response to the base oscillator signal. The alternating switching of the complementary FETs in response to the opposing phases of the base oscillator signal cause the common-gate FET amplifier to output a higher frequency local oscillator (LO) signal. The LO signal is coupled to the LO input of a mixer or mixer core of a type suitable for use in conjunction with a frequency multiplier.

Radio frequency (RF) mixer circuits having a complementary frequency multiplier module that requires no balun to multiply a lower frequency base oscillator signal to a higher frequency local oscillator (LO) signal, and which has a significantly reduced IC area compared to balun-based frequency multipliers. In one embodiment, the complementary frequency multiplier module includes a complementary pair of FETs controlled by an applied base oscillator signal. The complementary FETs are coupled to a common-gate FET amplifier and alternate becoming conductive in response to the base oscillator signal. The alternating switching of the complementary FETs in response to the opposing phases of the base oscillator signal cause the common-gate FET amplifier to output a higher frequency local oscillator (LO) signal. The LO signal is coupled to the LO input of a mixer or mixer core of a type suitable for use in conjunction with a frequency multiplier.

The invention discloses a passive wideband mixer, including a local oscillator balun, a radio frequency balun, a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, an inductive compensation unit, and a lossy inductive grounding network. The invention can realize a mixer with a bandwidth ratio of not less than 1:7, and can effectively suppress points with isolation deterioration without affecting the conversion loss over the entire frequency band. In the entire frequency band of this design, the isolation indicator between the local oscillator and radio frequency ports is optimized, which can well satisfy the application of the wideband mixer in a communication system.

The invention discloses a passive wideband mixer, including a local oscillator balun, a radio frequency balun, a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, an inductive compensation unit, and a lossy inductive grounding network. The invention can realize a mixer with a bandwidth ratio of not less than 1:7, and can effectively suppress points with isolation deterioration without affecting the conversion loss over the entire frequency band. In the entire frequency band of this design, the isolation indicator between the local oscillator and radio frequency ports is optimized, which can well satisfy the application of the wideband mixer in a communication system.