Switchable voltage level supplies for circuitry in a multi-mode communications chipset are disclosed. In an embodiment, a first voltage level is supplied to TX circuitry operating in a first mode having a first set of linearity and/or noise requirements. A second voltage level lower than the first voltage level is supplied to TX circuitry operating in a second mode having a second set of linearity and/or noise requirements looser than the first set of requirements. The first mode may be operation according to the GSM standard, and the second mode may be operation according to the W-CDMA standard.