一个用于非相干脉冲超宽带的能量检测接收机

Vol.32,No.6Journal of Semiconductors June2011 An energy detection receiver for non-coherent IR-UWB

Cai Li(蔡力),Huang Lu(黄鲁) ,Fu Zhongqian(傅忠谦),Yang Jinger(杨静儿),

and Wang Weidong(王卫东)

Department of Electronic Science and Technology,University of Science and Technology of China,Hefei230027,China

Abstract:A non-coherent receiver for impulse radio ultra-wide band(IR-UWB)is presented.The proposed re-

ceiver front-end consists of a high gain LNA,a high frequency detector and an intermediate frequency(IF)amplifier

to amplify the recovered signal and drive an external test instrument.To meet the requirements of high gain and

a low noise figure(NF)under moderate power consumption for the LNA,capacitor cross coupled(CCC)and

current reuse techniques were adopted.The detector consists of a squarer and an integrator.The overall circuit con-

sumes41.2mA current with a supply voltage of1.8V at a400MHz pulse rate.The resulting energy efficiency is

0.19nJ/pulse.A chip prototype is implemented in0.18- m CMOS.The die area is2.1 1.4mm2and the active

area is1.7 0.98mm2.

Key words:receiver;IR-UWB;non-coherent;LNA;detector

DOI:10.1088/1674-4926/32/6/065006EEACC:2570

1.Introduction

Since the Federal Communications Commission(FCC) opened the unlicensed3.1–10.6GHz frequency spectrum in 2002,the capability of high rate transmission in this open spectrum has attracted a lot of attention.Without reaching an agreement in the standard between different organiza-tions，UWB systems tend to fall into two broad categories: multi-band-orthogonal-frequency-division-multiplexing(MB-OFDM)and IR-UWB.One of the competing proposals to IR-UWB,which makes use of extremely short pulses to trans-mit information,has gained much attention for its potential to achieve high performance with low complexity,low cost and low power consumption.

Two main data demodulation schemes exist in the IR-UWB system,including coherent and non-coherent schemes, which show much difference in the architectures’complexity. Many works have been conducted in both schemesŒ1 5 .The author in Ref.[1]proposes a distributed pulse correlation re-ceiver achieving a250Mbps data rate.References[2,3]real-ize energy detection or demodulation with a squarer but Refer-ences[4,5]with a passive self-mixer.In Ref.[6],an ON/OFF keying(OOK)receiver is presented and the data rate can reach 500Mbps.However,the communication distance is restricted to30cm.With the characteristic of less complexity and no syn-chronization requirements,the non-coherent scheme shows a huge advantage over its counterpart.But to meet the demand of wireless high-definition video transmission,the performances of the front-end circuit should be ensured to make the receiver capable of working at data rates up to several hundred of mega-hertz.This makes the high-data-rate design of a non-coherent receiver a challenge because of its sensitivity to environmental noise and interference.

Figure1(a)shows a proposed low complexity receiver with an energy detector and an open-loop comparator.This re-ceiver was aimed at accommodating a communication system with a multi-megahertz data rate and a short range.

In this paper,a high performance OOK modulation re-ceiver front-end(Fig.1(b))based on an energy doctor(ED) is proposed.The received pulse is firstly amplified by a high performance LNA,which exhibits over46dB gain,over2GHz bandwidth and NF of2.5dB,and is then detected by an ED to recover the transmitted data.To make sure that the recovered signal is detected properly by an open-loop comparator,a low frequency buffer amplifier is added to make the output signal reach the comparator’s threshold voltage.The LNA consists of an LNA with input matching,a high frequency amplifier and a high frequency buffer amplifier,which use capacitor cross cou-ple(CCC)and current reuse techniques to reduce the noise fig-ure and power consumption.The detector consists of a squarer and a flipped-voltage follower current sensor(FVF-CS).The complete structure is shown in Fig.1(b).The prototype is im-plemented in a0.18- m CMOS process.

2.Receiver system consideration

The structure of the proposed non-coherent IR-UWB re-ceiver is illustrated in Fig.1(a)and the front-end structure is shown in Fig.1(b).This receiver front end system features large gain and low NF LNA,wide bandwidth IF blocks.The larger gain of the LNA makes less noise contribution from the next stage,making a lower NF receiver for higher sensitivity and data rate,which are priority demands of the system.Wide-band IF blocks consisting of a squarer and an amplifier are de-signed to accommodate high data rate communication.A1bit ADC,i.e.a comparator,is implemented by a high gain open loop amplifier with less complexity compared to an ADC with clocks,reducing the system’s power consumption.Moreover, the system’s requirement on linearity of the front-end is also re-duced.To drive the open-loop comparator,the input full scale

*Project supported by the Ministry of Industry and Information Technology of China(No.2009ZX03006-009).

Corresponding author.Email:luhuang@

Received16November2010,revised manuscript received17January2011c 2011Chinese Institute of Electronics