An enhanced-gain analog correlator for sensitivity improvement in coherent impulse radio receivers

A circuit technique called template range enhancement (TRE) is proposed for analog correlators employed in ultra-wideband coherent impulse radio (IR-UWB) receivers. In these receivers, the analog correlator multiplies the received signal with a template signal to detect the incoming pulses. Compared to other IR-UWB architectures, the coherent architecture has better signal-to-noise ratio (SNR) performance. To reduce the noise effect of baseband circuits in this receiver type, gain of the front-end blocks, which consists of a low noise amplifier and the analog correlator, should be increased. The conventional analog correlators, which are designed based on Gilbert cell topology, cannot provide sufficient gain for this purpose. The proposed TRE technique enhances the front-end gain of the receiver and improves the receiver sensitivity. A coherent receiver in 3.1-10-GHz bandwidth is designed and simulated based on this technique in a 0.18μm CMOS technology. Simulation results show that the TRE technique increases the sensitivity by about 6dB at 10^-6 bit error rate (BER) without consuming additional power. The receiver achieves a pulse rate of 500 Mbps with an energy efficiency of 69 pJ/pulse at 1.8 V supply.