Designing PGAs based on the Current Division Technique

Two highly linear, digitally programmable gain amplifiers (PGAs) are presented in this paper and compared in terms of linearity, frequency, area and power consumption. Both structures are characterized by their inherently high linearity and wide gain tuning range. Low distortion is achieved by means of an inherently linear MOST-only current division technique. A 3-bit prototype with constant bandwidth was integrated for each approach in a 0.35 mum CMOS process with 2.5 V supply voltage. Experimental results prove the high linearity of both configurations, which present distortion levels better than -68 dB for 1 MHz and IV_p-p, output signals.