Analog VLSI Design of Current-Mode DCT for 1-D Signal Processing

On-chip integration of discrete cosine transform (DCT) processor with CMOS MEMS microphones and CCD image sensors in low power devices are gaining significant attention of the researchers in the past few years. Digital design of DCT may not always be suitable for on-chip integration because of the higher power and area requirement. Some Analog counterparts of 2-D DCT have been proposed in the past for particularly image sensors. These designs include mainly switched capacitor technique. In this paper, we have proposed an analog 1-D DCT processor to be used mainly with MEMS audio sensors. The design includes current mode track and hold (T-H) circuit for serial to parallel conversion of signals and a current mode 8*8 vector matrix multiplier (VMM) for computing 8-point DCT. The implementations of T-H and VMM were done using CMOS operational transconductance amplifier (OTA) operating in subthreshold region. All theoretical designs were simulated and verified in SPICE using BSIM4 65nm CMOS process.