Versatile baseband signal input current splitter

Abstract

A current steering mechanism is provided in a radio transmitter (e.g., a multiband radio transmitter) to provide compatibility with a variety of baseband parts. Different proportions of an input signal current ('in') may be steered to a dummy load (), a mixer for a first band (), and a mixer for a second band (). In one example, five different loads are provided, one dummy load () and two different loads () for each band. Possibilities include: 1. All current steered into dummy load via transistor A; 2. All current steered into Band 1 mixer via transistor B; 3. All current steered into a Band 1 mixer via transistor C, causing 6 dB input signal amplification; 4. All current steered into Band 2 mixer via transistor E; 5. All current steered into a Band 2 mixer via transistor D, causing 6 dB input signal amplification; 6. Like cases 2-5 but with diversion of some portion of current via a dummy load for attenuation of input signal in 1 dB steps.