Digital multi-channel combination in transmitter design

In design of transmitter for base station, a challenge about signal combination is brought forward when multiple channels are required. To solve this problem a traditional method is to connect every channel with power combiners after power amplifier per channel. However, power loss and interference from large signals under this condition induce some troubles. In this paper, a replaceable way of combination what is called digital multi-channel combination is proposed. Every channel signal is connected in digital domain and converted to analog signal with a high performance DAC. Advantages from such design look obviously, less board space requirement, more simplified system design, and most importantly, less cost. On the other hand, some disadvantages such as multi- tone interference and harmonic intermodular on should also be taken into account. Finally, a practical example of digital multi-channel combination in trunking system application is given.