A current mode end-to-end signal path includes, a digital to analog converter (DAC), operating in current mode and an upconverting mixer, operating in current mode and operatively coupled to the DAC, wherein analog inputs and analog outputs of the DAC and the upconverting mixer are represented as currents, and the DAC generates a baseband signal.

A transmitter that reduces 3.sup.rd order harmonic (HD3) and inter modulation distortion (IMD3) for a gm stage of a mixer while reducing flicker noise is disclosed. The transmitter may include a balanced mixer, a transconductance stage connected to the mixer, and a bias circuit. The bias circuit may include a programmable current source configured to provide a reference current. Further, the bias circuit may include a replica circuit configured to replicate a DC signal of the transconductance stage. The bias circuit may also include a bias transistor configured to level shift a bias signal obtained from a signal source based on the reference current and the DC signal of the transconductance stage as determined from the replica circuit.

A starting circuit capable of further reducing an influence of a variation in the threshold voltage of a transistor is proposed. The starting circuit includes an N-type first MOS transistor whose threshold voltage is near 0 V, a resistor interposed between a source terminal of the first MOS transistor and a ground, and a control circuit controlling a gate voltage of the first MOS transistor. An amount of first current transmitted to a device to be driven and starting the device is controlled according to the control of the gate voltage.

A transmitter that reduces 3.sup.rd order harmonic (HD3) and inter modulation distortion (IMD3) for a gm stage of a mixer while reducing flicker noise is disclosed. The transmitter may include a balanced mixer, a transconductance stage connected to the mixer, and a bias circuit. The bias circuit may include a programmable current source configured to provide a reference current. Further, the bias circuit may include a replica circuit configured to replicate a DC signal of the transconductance stage. The bias circuit may also include a bias transistor configured to level shift a bias signal obtained from a signal source based on the reference current and the DC signal of the transconductance stage as determined from the replica circuit.

In certain aspects, an apparatus includes a transformer including an input inductor and an output inductor, wherein the input inductor is magnetically coupled to the output inductor. The apparatus also includes a transconductance driver configured to drive the input inductor based on an input signal. The apparatus further includes a feedback circuit configured to detect an output voltage swing at the output inductor, generate a regulated voltage at the input inductor, and control the regulated voltage based on the detected output voltage swing.

A starting circuit capable of further reducing an influence of a variation in the threshold voltage of a transistor is proposed. The starting circuit includes an N-type first MOS transistor whose threshold voltage is near 0 V, a resistor interposed between a source terminal of the first MOS transistor and a ground, and a control circuit controlling a gate voltage of the first MOS transistor. An amount of first current transmitted to a device to be driven and starting the device is controlled according to the control of the gate voltage.

The invention relates to a mixer circuit, which includes a transconductance stage circuit, a switch stage circuit and a load stage circuit which are electrically connected in sequence. The transconductance stage circuit is used to access a radio frequency voltage signal and convert the radio frequency voltage signal into a radio frequency current signal The switch-level circuit is used to access the local oscillator signal and the radio frequency current signal, and the switch-level transistor is turned on by using the local oscillator signal; the load-level circuit is used to convert the intermediate frequency current signal into a voltage signal for output. In the present invention, the transconductance stage circuit adopts a transistor superposition technology structure, which improves the conversion gain of the mixer; at the same time, it uses a source degenerate inductance structure, which further improves the conversion gain and linearity of the circuit.

The invention relates to a mixer circuit, which includes a transconductance stage circuit, a switch stage circuit and a load stage circuit which are electrically connected in sequence. The transconductance stage circuit is used to access a radio frequency voltage signal and convert the radio frequency voltage signal into a radio frequency current signal The switch-level circuit is used to access the local oscillator signal and the radio frequency current signal, and the switch-level transistor is turned on by using the local oscillator signal; the load-level circuit is used to convert the intermediate frequency current signal into a voltage signal for output. In the present invention, the transconductance stage circuit adopts a transistor superposition technology structure, which improves the conversion gain of the mixer; at the same time, it uses a source degenerate inductance structure, which further improves the conversion gain and linearity of the circuit.

In certain aspects, an apparatus includes a transformer including an input inductor and an output inductor, wherein the input inductor is magnetically coupled to the output inductor. The apparatus also includes a transconductance driver configured to drive the input inductor based on an input signal. The apparatus further includes a feedback circuit configured to detect an output voltage swing at the output inductor, generate a regulated voltage at the input inductor, and control the regulated voltage based on the detected output voltage swing.

The disclosed embodiments relate to the design of a system that implements an up-conversion mixer. This system includes a regulator-based linearized transconductance (g.sub.m) stage, which converts a differential intermediate frequency (IF) voltage signal into a corresponding pair of IF currents. It also includes a pair of current mirrors, which duplicates the pair of IF currents into sources of a set of switching transistors. The set of switching transistors uses a differential local oscillator (LO) signal to gate the duplicated pair of IF currents to produce a differential radio frequency (RF) output signal. Finally, a combination of capacitors and/or inductors is coupled to common source nodes of the set of switching transistors to suppress higher order harmonics in an associated common source node voltage signal.