A high-speed fully differential current switch

A high-speed differential-mode current switch is presented. The clock-feedthrough effect is reduced by swing-reduced drivers (SRD´s) and neutralized by dummy transistors. With the use of SRD´s, the switching transistors never operate in the triode region, which provides good matching of capacitance between the switching transistors and dummy transistors. The SRD´s also reduce the possible large current spikes on the outputs of the current switch. Analysis shows this current switch is ideal for high-speed current-mode signal processing. A continuous-time switched-current ΣΔ modulator using these current switches has been implemented in a 2 μm CMOS process and achieved a 59 dB dynamic range with a 50 MHz clock