A low power/noise emission LTE fully class A/B transmitter with a programmable output balun

Abstract

A current-mode transmitter for multi-standard wireless communications (including LTE) is presented. To limit both current consumption and RX-band noise a complete class A/B approach (from the DAC to the up-converter) is followed. The circuit is made up of three portions: a baseband that includes class B DAC and a second order low-pass filter (an active first order and a passive first order) combined with a class A/B up-converter. For LTE10 the current consumption (from a 1.8V regulated supply) is 47.5mW at 0dBm and 27.37mW at -6dBm output power respectively. The complete transmitter gives -160.5dBc/Hz RX-band noise injection at 30MHz offset (band 5 for LTE 10).