New CMOS 2 V low-power IF fully differential Rm-C bandpass amplifier for RF wireless receivers

A new CMOS fully differential bandpass amplifier (BPA) based on the structure of a transresistance (Rm) amplifier and capacitor is proposed and analysed. In this design, the Rm amplifier is realised by a simple inverter with tunable shunt-shunt feedback MOS resistor and tunable negative resistance realised by cross-coupled MOS transistors in parallel with a current source. The capacitor is in series with the input of the Rm amplifier, which realises the filter function and blocks the DC voltage. Under a 2 V supply voltage, the post-tuning capability of the gain can be as high as 55 dB whereas the tunable frequency range is 41-178 MHz. The power consumption is 14 mW and the dynamic range (DR) is 50 dB. The differential-mode gain is 20 dB and the common-mode gain is -25 dB so that the CMRR is 45 dB. Simple structure, good frequency response and low power dissipation make the proposed bandpass amplifier quite feasible for application in the IF stage of RF receivers