Switched-current (SI) is a current-mode analog sampled-data signal processing technique realizable in standard digital CMOS technologies. In this paper, new switched-current (SI) mirrors using OTAs (operational transconductance amplifiers) are proposed. These circuits are less sensitive to clock-feedthrough noise than conventional SI mirrors by virtue of linear I-V/V-I transformations. In addition, the current gain of the proposed mirror is electronically tunable. Not only inverting mirrors but also noninverting mirrors can be realized by this method.

In this paper, a new switched-current auto-tuning filter is proposed. Switched-current (SI) is a current-mode analog sampled-data circuit technique. An SI circuit can be realized using only standard digital CMOS technologies, and is capable of realizing high frequency circuits. The proposed filter is composed of SI-OTA (operational transconductance amplifier) integrators. The gain of an SI-OTA integrator can be electronically controlled by the bias current. The proposed filter is a current controlled filter (CCF) and a PLL technique was used as its tuning method. A 2nd-order SI auto-tuning low-pass filter with 100kHz cutoff frequency was designed assuming a 2µm CMOS process. The characteristics of this SI filter and its tuning characteristics were confirmed by SPICE simulations.