Two digitally programmable gain amplifiers based on current conveyors

Two digitally programmable gain amplifiers based on current conveyors (CCIIs) are presented. The first digitally programmable gain amplifier consists of a CCII, an operational transconductance amplifier (OTA), and current mirrors. The second one is composed of current conveyor analogue switches (CCASs). Both proposed digitally programmable gain amplifiers do not need switches but they maintain the linear gain at any digital signal levels similar to the digitally programmable gain amplifier using switches; hence the proposed amplifiers are easier to realize, use narrower chip area, and consume lower power. The first proposed amplifier is verified by constructing the circuit using the CCII in an AD844 IC, the OTA in a CA3080 IC, and some bipolar current mirrors. The second proposed amplifier is verified by simulating the circuit using the parameters extracted from the layout (including parasitic capacitance) in the 0.25 mu m MOS technology, the level 49 MOS model obtained through MOSIS is used. The results show that the operations of two proposed amplifiers are in accordance with the theories.