DPD receiver tweaked for 300MHz base station apps

A wideband RF-to-digital micromodule receiver has been debut by Linear Technology. The LTM9013 micromodule includes a high performance dual 14bit, 310Msps analogue to digital converter (ADC), a high IIP3 I/Q demodulator, two variable gain amplifiers, and 300MHz low pass filters.

The LTM9013's quadrature sampling architecture enables acquisition of up to 300MHz of signal bandwidth with IMD3 performance of 66dB across the entire band. The receiver is targeted for wideband, low IF receivers and wireless base stations implementing power amplifier (PA) linearisation with digital predistortion (DPD). The company's latest module leverages years of applications design expertise to offer high integration, ease of use, with repeatable and guaranteed system performance to increase production yields and time to market.

Due to increasing data demands from mobile users, next-generation base stations are now architected to achieve much higher transmit bandwidths of up to 60MHz. To linearise a transmit bandwidth of 60MHz, the predistortion feedback loop for the linearisation algorithm must acquire fifth order intermodulation products out to 300MHz. Digitizing the fifth order intermodulation distortion requires a very wide bandwidth, low noise receiver with an exceptionally flat pass band. The LTM9013 includes a 300MHz low pass filter that exhibits less than 1.3dB pass band ripple across the entire band. Since DPD is a feedback loop, the receiver (also called a transmit observation path receiver) benefits from low latency; a faster loop leads to better efficiency in the PA and therefore even lower power consumption. The ADC in the LTM9013 has just 5 clock cycles of latency.

The Linear's latest offering is packaged in a space-saving 15mm × 15mm ball grid array (BGA) package, utilising a multi-layer substrate that shields sensitive analogue lines from the digital traces to minimise digital feedback. Supply and reference bypass capacitance is placed inside the?Module package, tightly coupled to the die, providing space, cost and performance advantages over traditional packaging.

Further information regarding the LTM9013 can be accessed here.