A DSSS UWB transceiver using the 3.1 to 5 GHz band is implemented in 0.18 μm CMOS and includes a programmable pulse shaping circuit in the transmitter, an LNA with a NF of 4 dB and a 6th-order active LPF with a bandwidth of 500 MHz in the receiver. Die area of the transceiver is around 9 mm2. and the transceiver consumes 105 mW in the transmit mode and 280 mW in the receive mode from a 1.8 V supply.
"Currently, UWB pulse generators fall into three main categories , as shown in Fig. 2. In the first approach, a baseband pulse is generated using device characteristics, and then up-convert it to the target frequency band , . Similar to conventional narrow-band systems, this carrier-based approach circumvents the difficult task of directly generating UWB pulses. "
[Show abstract][Hide abstract] ABSTRACT: A new circuit technique, the distributed waveform generator (DWG), is proposed for low-power ultra-wideband pulse generation, shaping and modulation. It time-interleaves multiple impulse generators, and uses distributed circuit techniques to combine generated wideband impulses. Built-in pulse shaping can be realized by programming the delay and amplitude of each impulse similar to an FIR filter. Pulse modulation schemes such as on-off keying (OOK) and pulse position modulation (PPM) can be easily applied in this architecture. Two DWG circuit prototypes were implemented in a standard 0.18 mum digital CMOS technology to demonstrate its advantages. A 10-tap, 10 GSample/s, single-polarity DWG prototype achieves a pulse rate of 1 GHz while consuming 50 mW, and demonstrates OOK modulation using 16 Mb/s PRBS data. A 10-tap, 10 GSample/s, dual-polarity DWG prototype was developed to generate UWB pulses compliant with the transmit power emission mask. Based on the latter DWG design, a reconfigurable impulse radio UWB (IR-UWB) transmitter prototype was implemented. The transmitter's pulse rate can be varied from 16 MHz range up to 2.5 GHz. The bandwidth of generated UWB pulses is also variable, and was measured up to 6 GHz (- 10 dB bandwidth). Both OOK and PPM modulation schemes are successfully demonstrated using 32 Mb/s PRBS data. The IR-UWB transmitter achieves a measured energy efficiency of 45 pJ/pulse, independent of pulse rate.
"This field has gained momentum since a change in FCC regulations in 2002 that allows unlicensed communication using UWB. UWB signaling has many attributes that make it attractive for a wide range of applications; from ultra-low-power RFID tags and wireless sensors to streaming wireless multimedia and wireless USB at greater than 1Gb/s . "
[Show abstract][Hide abstract] ABSTRACT: A custom UWB transceiver chipset is presented that communicates in three 550 MHz-wide channels in the 3.1 to 5 GHz band by using pulse position modulation (PPM). The transmitter uses an all-digital architecture and calibration technique to synthesize pulses with programmable width and center frequency. No analog bias currents or RF oscillators are required in the transmitter. The receiver performs channel-selection filtering, energy detection, and bit-slicing. The receiver circuits operate at 0.65 V and 0.5 V, and can turn on in 2 ns for duty-cycled operation. The two chips are fabricated in a 90 nm CMOS process, and achieve a combined 2.5 nJ/bit at a data rate of 16.7 Mb/s.
Ultra-Wideband, 2007. ICUWB 2007. IEEE International Conference on; 10/2007
"The up-conversion architecture generally offers more diversity and control over the frequency spectrum, but at the cost of higher power since an LO must operate at the pulse center frequency . This architecture is usually found in high data-rate DS communication systems, where the pulse shape and center frequency must be well defined , . For most transmitters, the radiated frequency spectrum is defined by the shape of the pulse. "
[Show abstract][Hide abstract] ABSTRACT: This paper presents calculations for approximating the measured spectrum of pulsed signals in the high and low pulse-repetition-frequency (PRF) region. Experimentally verified peak and average power calculations are presented for pulse trains with no modulation and when modulated by random data using binary phase-shift keying (BPSK). A pulse generator is presented that is built using commercially available discrete components. BPSK pulses are generated at a PRF of 50 MHz. The output spectrum has a center frequency of 5.355 GHz and a -10-dB bandwidth of 550 MHz. A technique for pulse shaping is presented that approximates a Gaussian pulse by exploiting the exponential behavior of a bipolar junction transistor. This technique is demonstrated by a pulse generator fabricated in a 0.18-μm SiGe BiCMOS process. BPSK pulses are generated by inverting a local oscillator signal as opposed to the reference pulse, improving matching. Pulses are transmitted at a PRF of 100 MHz and centered in 528-MHz-wide channels equally spaced within the 3.1-10.6-GHz ultra-wideband band. Measurement results for both transmitters match well with calculated values.
IEEE Transactions on Microwave Theory and Techniques 07/2006; 54(4-54):1647 - 1655. DOI:10.1109/TMTT.2006.872053 · 2.24 Impact Factor
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