NXP launches d/a converter for next generation mobile networks
1 min read
Data traffic on the mobile networks is predicted to grow enormously over the next few years, reaching 6.3 x 10 8 byte per month by 2015. Alongside this, says NXP, will be 800 x 10 12 byte of data will be offloaded to fixed networks. Handling this level of data will need new approaches, it claims.
In particular, said Maury Wood, general manager of NXP's high speed converters product line, the macro basestation will be displaced in favour of a lot of smaller stations – from femtocells upwards.
Responding, the conmpany has launched the DAC1627D, a 16bit dual channel d/a converter which supports output update rates of up to 1.25Gsample/s. According to NXP, the part offers best in class single tone SFDR performance and two tone intermodulation distortion over an output bandwidth of 200MHz.
Developed primarily for wireless infrastructure applications, the DAC1627D1G25 is compliant with the Multi Carrier GSM spectral mask and with the LTE and LTE-Advanced transmit specification, making it suitable for use in multistandard basestations.
"The achievement announced today, the highest performing rf d/a converter, is a culmination of decades of experience and innovation in high performance data converters," said Wood.
Supplied initially with a parallel interface – but with a serial interface option likely to appear in the next few months – the converter can accept data at 312.5Mbit/s. Innovations include a low noise clocking scheme and one time current source calibration. "Up to 12 devices can be synced," Wood noted, "so all are 100% phase coherent."
A dsp in the device analyses the output from the basestation's power amplifier to increase efficiency. In doing so, it applies inverse transfer function filtering up to the seventh harmonic. With LTE using a 20MHz bandwidth, examining the seventh order harmonic requires a 140MHz bandwidth. "This device offers a bandwidth of 270MHz," Wood continued, "and is ideal for handling a 200MHz input signal."
