A low out-of-band noise LTE transmitter with current-mode approach

A 55nm CMOS current-mode transmitter for multistandard wireless communications (including LTE) that requires only 1.5mm² (with 4 output ports) is presented. The circuit is made up of two portions: a class A/B up-converter and a baseband that includes DAC, VGA, low-pass filter (two Biquad plus a passive first order) and class A/B signal conditioner. Combining a third order filter with the class A/B conditioner results in a reduction of both current consumption and RX-band noise injection. For LTE10, the consumption is 96mW and 34mW at 4dBm and at -10dBm output power, respectively. The complete transmitter gives -158dBc/Hz RX-band noise injection at 30MHz offset.