Constant bandwidth gain-linear programmable gain amplifier

This paper presents the design of a constant bandwidth gain-linear PGA with current density constant technique (CDCT). It consists of variable G_m cell, variable current source, current shunt circuit and active load. The gain can be changed by using digital controls, and the PGA bandwidth are independent of the gain setting by using CDCT; The PGA is designed in TSMC 0.13μm CMOS process. The PGA features a 0-18dB programmable gain rang with a 6dB gain-step and a gain accuracy of 0.5dB. For the overall circuit the IIP3 is 14.8dBm at 18 dB gain, while the input referred noise is 5.6nV/√Hz at 18 dB gain while consuming 200uA from 1.2V supply.