Mstar Semiconductor, Inc.

Shuo Yuan Hsiao

Chao-Tung Yang

Fucheng Wang

Min-Chiao Chen

Wei-Hsiu Hsu

A transconductor circuit used in a mixer for canceling second-order inter-modulation distortion includes a first transistor and a second transistor, of which the base (gate) ends coupled to a first input end and a second input end, for receiving a differential input signal; and a negative feedback circuit, of which the input end coupled to the emitter (source) ends of the first transistor and the second transistor, of which the out end coupled to the base (gate) ends of the first transistor and the second transistor, for adjusting the voltage of the base (gate) of the first transistor and the second transistor according to the difference between a reference voltage and the detected voltage of the emitter (source) of the first transistor and the second transistor.

Mixer for canceling second-order inter-modulation distortion and associated transconductor circuit

A signal processing circuit includes a differential input circuit, a first DC filter, a second DC filter, a differential transconductance circuit, and a differential converting circuit. The differential input circuit includes first and second input circuits respectively for receiving first and second input signals to generate first and second processed signals. The first DC filter and the second DC filter, respectively coupled to the first and the second input circuits, receive the first and the second processed signals and output first and second voltage signals. The differential transconductance circuit includes first and second transconductance circuits, respectively coupled to the first and the second DC filters, for converting the first and the second voltage signals to first and second current signals. The differential converting circuit includes first and second converting circuits, respectively coupled to the first and the second transconductance circuits, for mixing the first and the second current signals with first and second clock signals to generate first and second output signals.

Signal processing circuit with improved linearity

A mixer having high linearity and an associated transconductor combining programmable gain amplifier and mixer functions are provided. The transconductor includes first and second resistors, a differential amplifier, first and second feedback circuits, and first and second transistors. A differential voltage signal is inputted to first and second input ends of the differential amplifier via the first and second resistors. The first and second feedback circuits are provided between a first output end and the first input end, and a second output end and the second input end of the differential amplifier, respectively. The first output end outputs a first output signal for controlling a first current passing through the first transistor. The second output end outputs a second output signal for controlling a second current passing through the second transistor. The first current and the second current determine a differential current.

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Hsinchu Hsien, Taiwan

Shuo Yuan Hsiao